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APPROVED AS AMERICAN STANDARD BY THE AMERICAN STANDARDS ASSOCIATION ASA NO.: Zll.69-1953 UDC 662.75J: 620.1

Standard Method of Test for KNOCK CHARACTERISTICS OF MOTOR FUELS BY THE RESEARCH METHOD1

ASTM Designation: D 908-55 Adopted,

1951;

Revised,

1953, 1955.8

This Standard of the American Society for Testing Materials is issued under the fixed designation adoption as standard

D

908; the final number indicates the year of original or, in the case of revision, the year of last revision.

with normal heptane that matches the knock characteristics of the fuel when compared by this method.

Scope 1.

This method describes the test

for determining the knock character istics, in terms of ASTM research oc tane numbers, of fuels for use in sparkignition engines.

Outline of Method 3. The Research octane number of a

Definition 2.

ASTM Research

knocking

blends of the reference fuels of known octane number at 600 rpm under standard operating conditions. This is

Octane Number

of a fuel is the whole number nearest the percentage by volume of zsooctane

(2,2,4-trimethylpentane)

by comparing its with those for tendency

fuel is determined

done by varying the compression ratio for the sample to obtain the standard knock intensity as defined by a guide curve and as measured by an electroni cally controlled knockmeter. When the knockmeter reading for the sample is bracketed between those for two refer ence blends differing by not more than two octane numbers, the rating of the sample is calculated by interpolation.

in a blend

1

Under the standardization procedure of the Society, this method is under the juris diction of the ASTM Committee D-2 on Petroleum Products and Lubricants. 2 Prior to adoption as standard, this method was published as tentative from 1947 to 1951, being revised in 1948. In 1953, this method was revised to elim inate the bouncing pin as authorized equip ment on and after January 1, 1954. In 1955, the new corrections for microm eter settings and intake-air temperature which depend upon barometric pressure were put into effect. Sections 6(fc), 8, and 10(6) were revised to conform with the new Table VI in regard to intake-air tem perature.

Apparatus 4.

The

knock

trated in Fig.

testing

unit

illus

consists of a singlecylinder engine of continuously vari 3

able compression 19

ratio, with suitable

20

RESEARCH METHOD (D

A — Surge Tank. B — Coolant Condenser. C — Exhaust Surge Tank. D — Exhaust Manifold. E — Crank for Adjusting Compression

F— Oil Drain Cap. G — Scrap Fuel Can, Closed for Safety.

FIG.

908

-

H— Oil Filter. I — Ignition Breaker. — Cylinder Clamp. K — Air Intake Thermometer. L — Ignition coil. M— Detonation Meter, Model 501-AP.

J Ratio.

55)

3.— RESEARCH

UNIT.

RESEARCH METHOD (D and

loading and accessory equipment

mounted on a stationary

instruments,

The engine and equipment spec ified in Appendix I on Apparatus shall be used without modification and in base.

stalled as directed in Appendix

V on

Installation and Assembly. It is im portant to provide a proper foundation for the unit

as described

in Section

606

of Appendix VI on Building and Utility Requirements.

It

is necessary to keep

as described

in Appendix

IV

on

Maintenance. The panel-mounted detonation me ter, Model 501-AP,3 Fig. 3, and knockModel 501meter, or desk-mounted Fig. 2, shall be used to measure knock intensity. With the detonation meter a pickup, Type D-l, £ in. in di A,3•3°

ameter with 18 threads per inch, is re quired and may be purchased with the

A constant voltage transformer4

meter.

should be used to prevent instability of

Available from the Waukesha Motor Co., Fuel Research Division, Waukesha, Wis. Also available from The Solartron Electronic Group Ltd., Solartron Works, Queens Road, Thames Ditton, Surrey, Eng land. 80 Detonation meter Model 501 may also 3

be used. 4

The detonation

conversion of the line voltage to the instru voltage may be purchased with the meter or from electrical supply ment operating houses.

If

the frequency of the power source

is less than 50 cycles, a detonation altered

to

accommodate

the

meter

particular

frequency available must be used.

21

Reference Materials 5.

ASTM Knock

Test

Reference

Fuels,8 conforming to the specifications and requirements in Section 214(a) of Appendix on Reference Materials and Blending Accessories, are the fol

II

lowing: fsooctane (a) ASTM methylpentane), (b)

ASTM ASTM

(2,2,4-tri-

n-heptane, 80 octane number

blend of (a) and (b),6 (d) Such other blends of (a) and (b) as may be adopted. (c)

Toluene conforming to the specifi cations in Section 214(e) of Appendix is required for blends with ASTM knock test reference fuels to standard

II

ize engine conditions.

6

Operating Conditions

The following standard operating on Op (see Appendix eration for further details) are manda tory: (a) Engine Speed, 600 ± 6 rpm, with a maximum variation of 6 rpm during a test. (b) Spark Advance, constant, 13.0 6.

conditions

III

deg.

(c) Spark Plug Gap, 0.020 ± 0.005 in. (d) Breaker-Point Gap, 0.020 in. (e) Valve Clearances, 0.008 ± 0.001

meter requires a 115-v

regulated voltage source and its total power requirements are less than 60 va. Regulating and step-down regulating transformers for

- 55)

knockmeter readings due to line voltage fluctuations.

the apparatus in good mechanical con

dition,

908

in., measured with the engine hot and running under standard operating conFuel "C" (Section 202 of Appendix II) is available for those who prefer the use of a secondary reference fuel for routine test ing. 5

"X" (Section 203(c) of Appendix is also acceptable as a standardization fuel. II)

•Fuel

RESEARCH METHOD (D

ditions on a reference fuel of

80 octane

Lubricating Oil, SAE Saybolt Universal viscos

30, having

ity of

58 to 70 sec at 210

termined

by

(99

C) de

ASTM Method D

Oil Pressure,

(g)

F

Crankcase a

(f)

number.

25

to

88.7

30 psi under

908

- 55)

for (n) Fuel- Air Ratio, adjusted maximum knock as follows: At each ratio and for each fuel being tested, adjust the fuel-air ratio by varying the carburetor fuel level in increments, until the adjustment maximum knockmeter that produces compression

a

22

It

obtained.

required

sensitive element completely immersed

the size of the metering jets to meet

in the crankcase oil.

this requirement. (o) Standard Knock Intensity, ob blend of fsooctane and tained with a

normal

a

F

F

1.5 C) constant (100 ± test. ±1 (±0.5 C) during (j) Intake Air Humidity, 25 to

50

grains of water vapor per pound of dry air, as provided in Section 114, of

heptane,

under

operating

conditions

and

micrometer

at

the standard

of this method reading

corre

sponding to the octane number of the blend used and the prevailing baro metric

Table

in accordance with and correction Table VI.

pressure

a

it

I.

When air of this humidity Appendix prevails in the engine room through the operation of natural factors or air may be used without conditioning, further conditioning, its humidity be ing determined by use of the type of sling psychrometer described in ASTM Method D 337, for Determination of Relative Humidity.8 (k) Intake Air Temperature, meas ured at carburetor entrance with

be between 0.8 and

may be necessary to change

a

± within

212

V

Temperature,

3

(i)

Coolant

It

1.8 in.

is

that this fuel level

is

reading

(h) Oil Temperature, 135 ± 15 (57 ± 8.5 C) with the temperature

F

operating conditions.

mercury thermometer

within

and maintained

±2F

Starting and Stopping Engine is

7. (a) Starting the Engine.— While the engine being motored, turn on

the ignition and start the engine by the

setting

carburetor

to draw

fuel

from one float bowl.

— (b) Stopping the Engine. Turn off the fuel, then the ignition, drain all fuel bowls, and motor the engine for min before stopping the synchronous

ameter at the throat.

operating periods, close both valves by turning the flywheel to tdc on the

(1)

specified

clearance volume of

± 0.5 ml to the top face of the pick-up hole as measured by either of the "tilt" procedures described in Sec tions 302 and 303 of Appendix III. 1955

Book of ASTM Standards, Part Book of ASTM Standards, Part

warping

of valves and seats between

compression stroke.

Obtaining Standard Knock Intensity 8.

With the engine at equilibrium

temperature

and

the

carburetor

set

for maximum knock, obtain standard knock intensity, Section 6(o), at the

5.

7

1955

8

140

To avoid possible corrosion and

motor.

micrometer

7.

Table

V

center and with

a

1

(m) Micrometer Adjustment, set to read 0.500 in. (5.5 to compression at with the piston top dead ratio)

1

(±1.1 C) of the tem for the prevailing barometric pressure in Table VI. Carburetor Venturi, ^ in. di perature

setting

obtained

from

and corrected in accordance

RESEARCH METHOD (D

908

- 55)

23

TABLE V.— MICROMETER SETTINGS FOR STANDARD KNOCK INTENSITY AT A BAROMETRIC PRESSURE OF 29.92 IN. OF MERCURY. For Use at All Altitudes, 9/16 in. Venturi. See Table RlUARCH OCIANI NUMBIl

0.0

VI for

0.1

Corrections 0.3

0.2

for Other Barometric Pressures. 0.4

0.5

0.6

0.7

0.8

0.9

Research OCTAKI

Nuiibii

Micrometer Setting., in.

44

0.559 0.557 0.654 0.651 0.648

0.650 0.666 0.554 0.651 0.547

0.569 0.656 0.553 0.550 0.647

0.669 0.660 0.653 0.660 0.647

0.558 0.656 0.653 0.650 0.547

0.558 0.565 0.663 0.549 0.646

0.658 0.666 0.552 0.649 0.546

0.558 0.665 0.552 0.549 0.546

0.657 0.655 0.652 0.648 0.646

0.557 0.654 0.651 0.648 0.646

40 41 42 43 44

45 46 47 48 49

0.546 0.541 0.638 0.535 0.531

0.644 0.641 0.538 0.534 0.631

0.644 0.541 0.537 0.634 0.530

0.644 0.540 0.637 0.533 0.630

0.543 0.540 0.537 0.633 0.529

0.643 0.640 0.636 0.533 0.529

0.543 0.539 0.636 0.532 0.529

0.542 0.639 0.636 0.532 0.528

0.642 0.539 0.635 0.532 0.528

0.642 0.638 0.535 0.531 0.628

45 46 47 48 49

(2

H

0.527 0.624 0.520 0.516 0.612

0.527 0.523 0.520 0.616 0.512

0.527 0.623 0.519 0.616 0.511

0.526 0.623 0.619 0.616 0.611

0.526 0.622 0.618 0.515 0.511

0.525 0.622 0.518 0.614 0.610

0.525 0.521 0.518 0.514 0.610

0.525 0.521 0.517 0.613 0.610

0.524 0.521 0.617 0.613 0.609

0.624 0.620 0.517 0.613 0.609

50 51 62 53 64

65 68 67 58 69

0.508 0.604 0.500 0.496 0.492

0.508 0.504 0.500 0.496 0.492

0.607 0.503 0.499 0.496 0.491

0.507 0.503 0.499 0.495 0.491

0.607 0.503 0.499 0.495 0.490

0.506 0.502 0.498 0.494 0.490

0.606 0.502 0.498 0.494 0.489

0.505 0.602 0.497 0.493 0.489

0.605 0.601 0.497 0.493 0.489

0.505 0.601 0.497 0.492 0.488

55 66 57 58 59

50 «1 82 (3 «4

0.488 0.483 0.479 0.474 0.470

0.487 0.483 0.478 0.474 0.470

0.487 0.482 0.478 0.473 0.469

0.487 0.482 0.477 0.473 0.469

0.486 0.481 0.477 0.473 0.468

0.486 0.481 0.477 0.472 0.468

0.485 0.481 0.476 0.472 0.467

0.485 0.480 0.476 0.471 0.467

0.484 0.480 0.475 0.471 0.466

0.484 0.479 0.475 0.471 0.466

60 61 62 63 64

85 68 67 68 69

0.466 0.461 0.456 0.451 0.446

0.465 0.460 0.455 0.450 0.445

0.465 0.460 0.455 0.460 0.445

0.464 0.459 0.454 0.449 0.445

0.464 0.459 0.454 0.449 0.444

0.463 0.458 0.453 0.448 0.444

0.483 0.458 0.453 0.448 0.443

0.462 0.457 0.462 0.447 0.443

0.462 0.457 0.452 0.447 0.442

0.461 0.456 0.451 0.447 0.442

65 66 67 68 69

70 71 72 73 74

0.441 0.436 0.431 0.426 0.420

0.441 0.436 0.431 0.426 0.419

0.440 0.436 0.430 0.426 0.419

0.440 0.435 0.430 0.424 0.418

0.439 0.434 0.429 0.423 0.418

0.439 0.434 0.429 0.423 0.417

0.438 0.433 0.428 0.422 0.416

0.438 0.433 0.427 0.422 0.416

0.437 0.432 0.427 0.421 0.415

0.437 0.432 0.426 0.421 0.415

70 71 72 73 74

75 76 77 78 7»

0.414 0.408 0.401 0.394 0.387

0.413 0.407 0.400 0.394 0.387

0.413 0.406 0.400 0.393 0.386

0.412 0.406 0.399 0.392 0.386

0.411 0.405 0.398 0.392 0.384

0.411 0.405 0.398 0.391 0.384

0.410 0.404 0.397 0.390 0.383

0.410 0.403 0.396 0.390 0.382

0.409 0.402 0.396 0.389 0.381

0.409 0.402 0.395 0.388 0.381

75 76 77 78 79

80 81 82 83 84

0.380 0.373 0.366 0.368 0.361

0.379 0.372 0.366 0.368 0.360

0.378 0.371 0.364 0.367 0.349

0.378 0.371 0.364 0.356 0.349

0.377 0.370 0.363 0.365 0.348

0.376 0.370 0.362 0.365 0.347

0.376 0.369 0.362 0.354 0.346

0.375 0.368 0.361 0.353 0.346

0.374 0.867 0.360 0.352 0.345

0.374 0.367 0.359 0.352 0.344

80 81 82 83 84

85 86 87 88 80

0.343 0.334 0.326 0.317 0.307

0.342 0.334 0.326 0.316 0.306

0.341 0.333 0.324 0.315 0.306

0.340 0.332 0.323 0.314 0.304

0.339 0.331 0.322 0.313 0.303

0.339 0.330 0.321 0.312 0.302

0.338 0.329 0.320 0.311 0.301

0.337 0.328 0.319 0.310 0.300

0.336 0.327 0.318 0.309 0.299

0.335 0.327 0.317 0.308 0.298

86 86 87 88 89

00 01 02 93 04

0.297 0.287 0.276 0.266 0.254

0.296 0.288 0.275 0.264 0.252

0.296 0.286 0.274 0.263 0.261

0.294 0.284 0.273 0.262 0.250

0.293 0.283 0.272 0.280 0.248

0.292 0.282 0.271 0.269 0.247

0.291 0.281 0.270 0.258 0.246

0.290 0.280 0.269 0.257 0.244

0.289 0.279 0.268 0.256 0.243

0.288 0.278 0.267 0.255 0.242

90 91 92 93 94

05 06 07 08 09

0.241 0.227 0.213 0.197 0.179

0.240 0.226 0.211 0.196 0.177

0.238 0.224 0.210 0.193 0.175

0.237 0.223 0.208 0.192 0.174

0.236 0.222 0.206 0.190 0.172

0.234 0.220 0.206 0.188 0.169

0.233 0.218 0.203 0.186 0.167

0.231 0.217 0.202 0.184 0.165

0.230 0.216 0.200 0.182 0.163

0.229 0.214 0.199 0.180 0.182

95 96 97 98 99

100

0.160

41

63

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MAINTENANCE

104 A

B

C

P A — Valve Tappet. B — Tappet Guide. C — Tappet Guide Capscrew. D — Camshaft. E — Timing Pointer. F — Rear Main Bearings. G—Rear Oil Thrower. H— End Play Adjusting Nut. I— Flywheel Key. J— Flywheel Nut. K— Felt Oil Retainer. L— Oil Retaining Plate. M — Flywheel. N — Rear Bearing Adapter. O — Balancing Piston Eccentric. P— Oil Heater. Q— Balancing Piston Guide.

FIG.

26.— SECTIONAL

E

D

F

0

R — Balancing Piston Pin. S — Balancing

Piston.

T — Balancing Piston Connecting

Rod.

U — Crankshaft. V — Front Main Bearing. W — Crankshaft Gear. X — Tachometer Drive Gear. Y— Front Oil Thrower. Z — Gear Cover.

AA— Felt Oil Retainer. BB— Front Crankshaft Nut. CC — Neon Tube Carrier. DD— Spark Timing Scale. EE — Ignition Breaker Drive.

FF— Cam

Gear.

GG — Camshaft Bearing Capscrews.

VIEW OF HIGH-SPEED CRANKCASE.

MAINTENANCE

105

D

A — Valve Tappet.

P — Rear

B— Tappet Guide. C — Tappet Guide Capscrew. D — Camshaft. E — Timing Pointer. F — Rear Main Bearings.

Q

I— End

FIG.

Shims.

27.— SECTIONAL

G

Bearing Adapter.

— Counterbalanced

T— Oil

Play Spacing Collar. — Flywheel Key. K — Flywheel Nut and Lock. L — Split Collar, Centers Flywheel. M— Felt Oil Retainer. N — Oil Retaining Plate. O—Flywheel.

J

F

Crankshaft.

R— Oil Heater. S— Oil Relief Valve.

G— Rear Oil Thrower.

H— End Play

E

Pump.

U — Front Main Bearing. V — Crankshaft Gear. W — Tachometer Drive Gear. X— Front Oil Thrower. Y— Felt Oil Retainer. Z — Neon Tube Carrier Collar. A A — Front Crankshaft Nut and Lock. BB — Cam Gear. CC — Ignition Breaker Drive. DD — Camshaft Bearing Capscrews.

VIEW OF LOW-SPEED CRANKCASE.

MAINTENANCE

106

bind of the bearing. If the lead strip is used, remove and measure its thickness with a micrometer. This is the bearing clearance. If the "Plastigage" is used, the flattened strip is placed on the calibration chart supplied with it and the clearance is read there firmly seated and that there is

from. Excessive

a slight

clearance can be reduced by peeling one or more layers

from the bearing shims, except for replaceable shell-type

bearings which

require the installation of a new set of shells.

— (b) Piston-Pin Bushing. The bronze piston-pin bushing should be in spected every 2000 hr and replaced when the clearance exceeds that listed

XII.

in Table

The oil hole in the bushing must

be

in alignment with the oil

passage in the rod.

Alignment of Connecting Rod. — The connecting rodshould be checked periodically for alignment. This can be done with any of the alignment jigs available in automotive service stations. When the connecting rod is properly aligned, the following conditions are met : (i) The piston wall is perpendicular to the axis of the journal within 0.003 in. {2) The piston pin is not twisted more than 0.002 in. in the length (c)

of the big-end bearing. (3)

The centerline of the connecting rod is perpendicular to the axis of the bearings within 0.003 in.

Camshaft 424. (a) CFR-48 Crankcase. — The camshaft is supported by precisiontype sleeve bearings at both ends. It is not interchangeable with the cam shaft of the high-speed and low-speed engines. The flanged bearing at the timing gear end controls the end-play. The camshaft with timing gear may

withdrawn after stripping the front end of the engine and removing the front bearing retaining screws, item 25, Fig. 25. It is good practice to remove the valve lifters, item 58, Fig. 24, and guides, item 56, before re moving the camshaft. If end-play is over 0.007 in., the front camshaft bear ing should be replaced to give a total end-play of 0.002 to 0.005 in. when the gear is again drawn into position. The running clearances of the front cam shaft bearing should be 0.0015 to 0.003 in., and of the rear bearing 0.002 to 0.0035 in. Install new bushings when clearances of 0.004 in. are exceeded, aligning the locating screw hole in the rear bushing with the locating screw. No line boring is required. When reassembling, make sure the gear teeth marked -X" mesh so that the valve timing will be correct. — The camshaft of the high-speed (b) High- and Low-Speed Crankcases. engine is supported by a bronze bushing at the front and a babbit-lined bearing at the rear. The camshaft of the low-speed engine is supported by two bronze bushings. The bushing at the timing-gear end controls the end-play. After stripping the front end of the engine, including the timing-gear cover, the camshaft may be removed by taking out the cap be

MAINTENANCE

107

screws, GG, Fig. 26, and DD, Fig. 27, behind the cam gear. These capscrews hold the bearing bushing to the crankcase. It is good practice to remove the cam followers, A, before pulling the shaft. If excessive end-play develops, the camshaft shoulder directly behind the gear should be ground sufficiently to give the total end-play listed in Table XII when the gear is again drawn into position. Install new bushings and line-bore them when

the running clearances listed in Table XII are exceeded. Make certain that the oil holes in the bushings align with the oil passages in the crankcase

wall. When reassembling, make the gear teeth marked timing will be correct.

X mesh

so

that valve

Valve Timing 425. (a) Checking the valve timing should not be necessary except in cases of complete disassembly and overhaul. When doing so always turn the flywheel forward to avoid errors due to backlash in the timing gears.

— (b) Timing Procedure. When assembling timing gears, the teeth marked X should mesh so that the valve timing will be correct. When the cylinder assembly is removed the timing can be checked with a dial gage the following procedure may be the intake and exhaust push rods. Swing both rocker arms used: Remove to a vertical position. Mount a dial indicator gage on the rocker-arm sup port bracket with the indicating plunger directly over and pointing toward the intake tappet. Place a piece of drill rod between the intake tappet and mounted

on the valve tappet. Otherwise

the indicating plunger. This rod should be approximately \ in. in diameter, having a spherical end where it rests in the tappet and an indentation on the other end in which the indicating plunger rests. Set the dial gage so that its plunger is approximately in the middle of its travel and the tappet is on the base circle or back face of the cam. Rotate the flywheel until the indicator shows that the cam has just lifted the tappet approximately 0.010 in., and further rotation shows that the tappet dwells momentarily without additional lift, and then begins to lift again. Make a pencil mark on the flywheel opposite the timing pointer at the beginning of the dwell interval and again at the end when the tappet just starts to rise. Effective valve opening starts halfway between these two marks. Repeat this operation two or three times to verify the angle at which the lift is obtained. That part of the cam below the initial 0.010-in. lift is the quieting ramp and does not contribute to the effective valve opening. For the intake valve the open ing point should be at the timing line on the flywheel marked INO-010 for 10 deg atdc for those divided into degrees on their the cam timing is not within f in. of the INO-010

early type flywheels, or at entire circumference.

If

or 10-deg mark on the flywheel, the camshaft needs retiming either by shift ing the cam gear with respect to the crankshaft or by relocating the cam gear on its shaft by using one of the other three keyways. Shifting the tim ing one full gear tooth will make 1.48 in. change on the flywheel. The extra

108

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109

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110

keyways on the gear permit adjusting the timing by 0.37-in. increments on the flywheel. Earlier models without the multiple keyway cam gears should

with new gears to provide close timing adjustment. The valve timing is shown in Fig. 30 and is as follows:

be equipped

Closes

Intake . . .

10

Exhaust

40 deg bbdc

.

dog atdc

34 deg abdc 15 deg

atdc

The contour of the valve cam may be checked in a similar manner and should be within the limits shown in the timing diagram.

HOLD TO ±0.37 IN. OR ON FLYWHEEL

2j

Valve Clearance for Timing Check

FIG.

30.— VALVE-TIMING

= 0.010 in.

DIAGRAM.

CFR-48 Crankcase. — Paragraphs (a) and (b) are generally applicable to the CFR-48 crankcase except for the following: The camshaft gear has 76 teeth, whereas the high- and low-speed gear has 68 teeth. Thus, shifting the timing one full gear tooth will make 1.320 in. change on the flywheel. The extra keyways in the gear permit adjustment of the timing by 0.330-in. (c)

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111

increments on the flywheel, or within 1 deg, 11 min of a given fixed mark. The valve-timing diagram, Fig. 30, is the same for all engines.

Valve Tappets 426. The mushroom valve tappets are assembled in cast iron guides, B, Figs. 26 and 27, and should just drop by their own weight when new. When a clearance of 0.003 in. develops, replace the guides. Do not use a tappet which shows signs of excessive wear. Discard any tappet which has a groove on the cam contact face, as this interferes with rotation and affects the valve clearance.

Balancing Systems 427. (a) CFR-48 Crankcase. — The rotating balance system should be inspected every 2000 hr. The two shafts are carried in four identical pre cision-type bushings, item 20, Fig. 24, held in the crankcase by locating screws. Balancing shaft running clearance should be 0.0015

to 0.003 in.

When running clearance exceeds 0.0035 in., new bearings should be in stalled. Line boring is not required when bearings are replaced. End thrust is absorbed by the thrust plates, item 162, and end-play should be 0.002 to 0.006 in. If end-play exceeds 0.010 in., new thrust plates should be used. The gears are installed with the flat faces to the front and must be timed to the engine so that both eccentric weights are at bdc when the engine piston is at tdc. The full engine gear train is marked at assembly with "X" and "C" marks at gear-timing points, but service replacement gears are not so marked. The heavy weights (Part No. 109565) are loaded with two lead plugs apiece and are used in pairs to balance the cast-iron piston. Tightening torque on the nuts holding the weights to the balance shafts is 100 ft-lb. Remove the weights and thrust-plate cap screws, item 163, to withdraw shafts from the crankcase.

— (b) High-Speed Crankcase. The balancing piston assembly, R, S, and T, Fig. 26, of the high-speed engine should be inspected every 2000 hr.

Give particular attention to the bearings of the connecting rod, T, and replace them when the clearance exceeds 0.006 in. Examine the pistons, S, for signs of scuffing or wear. Note that these balancing pistons are supplied to match engine pistons. The following table shows the weights and part numbers of the balancing pistons and the corresponding Engine Piston

Material Part No Piston weight, Total weight,

cast iron 23204-B oz oz

rod-bearing: End-play, in Clearance, in

engine pistons: Balancing Piston

cast iron 105462-A

52.3

±

0.25

47.5 ± 0.25

(53.25

± 0.25

56.9 ± 0.25

Connecting

0.008 to 0.014

0.003 to 0.009

0.0011 to 0.0036

0.003 to 0.005

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Idler Gear 428. CFR-48 Crankcase.

by

— The idler gear, item

145,

Fig.

24, is retained

thrust washer and cap screw and drives the oil pump shafts. The running clearance of the bushing is 0.0015 to 0.003 in. and end-play is 0.002 to 0.004 in. Replacement should be made when running clearance exceeds 0.004 in., or end-play exceeds 0.008 in. Replacing the gear bushing requires machine reaming concentric with on the stub shaft

a

as well as the balancing

the outside diameter.

Lubrication System 429. (a) CFR-48 Crankcase. — The oil pump is mounted externally on the gear cover and draws oil through an external line from the sump oil screen. The oil screen is easily removed through the gear cover opening for cleaning. Oil is delivered to an external oil pressure-relief valve, and then

to the crankshaft, camshaft, balancing shaft, idler shaft, connecting rod, and piston-pin bearings under full pressure. The timing gears are oiled by an intermittent spray jet controlled by holes in the front camshaft bearing. — Both engines have positively (b) High- and Low-Speed Crankcases. driven oil pumps. The pump forces oil under pressure to the crankshaft, camshaft, connecting rod, piston-pin bearings, and to the timing gears through a special lead.

Oil Pressure Adjustment Oil pressure should be adjusted to 30 psi for all engines. — The oil-pressure relief valve is mounted hori (a) CFR-48 Crankcase. zontally below the crankcase side door on the camshaft side of the engine. Oil pressure is adjusted by means of the screw under the cap-nut on the 430.

valve body.

— The oil-pressure relief valve is mounted (b) High-Speed Crankcase. vertically on the camshaft side of the crankcase. Oil pressure is adjusted

by means of the screw under the cap-nut on the valve body. — The oil-pressure relief valve is mounted (c) Low-Speed Crankcase. internally in the main oil header. Oil pressure is adjusted by means of the spring-loaded relief valve, S, Fig. 27. — (d) Low Oil Pressure. -If the specified pressure cannot be maintained with the proper grade and quantity of oil in the system, it may be due to clogging of the strainer screen or to foreign matter on the relief valve seat, which holds the relief valve open. The drilled oil passages in the crankcase are closed at the outside end by screw plugs. Whenever the camshaft, crankshaft, or oil pump is removed, the oil passages should be opened and

any obstructions removed with compressed air and a stiff brush. Do not apply air to any passage without removing the shafts as this will blow the dirt into the bearings.

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Oil Filter 431. The oil filter contains

of cotton waste which should be replaced at least every 500 hr, after draining the filter, Fig. 1, by removing the 5 oz

J,

plug.

Crankcase Oil Leaks 432. (a) CFR-48 Crankcase.— If an oil leak develops, replace the faulty oil seal. The front seals are pressed into the gear cover to seal around the front of the camshaft and the crankshaft. The camshaft seal, item 93, Fig. 24, rides on a sleeve, item 169, which is held in place by the camshaft nut and sealed to the camshaft by an internal

"0"

ring, item 170. The crank

shaft front seal rides on the ignition-indicator disk spacer, item 91, which is sealed to the crankshaft by an internal "0" ring, item 92. The rear oil seal, item 82, is pressed into a stationary carrier, item 81, which is sealed to the main-bearing adapter by two external "0" rings, item 83. The rear mainbearing adapter is sealed to the crankcase by an "0" ring, item 30. An

"0" ring, item 33, seals the oil-pressure transfer passage to the rear main bearing. No relative motion occurs at "0" rings in operation. All the rotating shaft seals are of the synthetic-rubber lip type and are installed with the sharp edge of the lip toward the crankcase. Make sure that the lip runs on a No crankcase breather valve is used, as it is un necessary with this type of sealing. — Oil leaks usually indicate that (b) High- and Low-Speed Crankcases. clean polished surface.

the breather valve is not functioning properly (for details, see Section 433). If oil leakage occurs from the rear main bearing when the breather valve is clean and working properly,

it usually can

be remedied

in the following

manner: Remove the flywheel and oil-retaining cover. (2) Clean and polish the contact surfaces of the flywheel spacer, H , Fig. 26, oil thrower, G, thrust washer, shims, and end of the (1)

bearing so that when these parts are assembled, there will be no clearance between them through which the oil can reach the shaft. (3)

(4) (6) (6) (7)

Examine the felt, K, in the oil retaining plate, L, to make sure that it is in good condition and fits snugly around the flywheel spacer. In the high-speed crankcase the threaded nut should be drawn tight. In the low-speed crankcase the spacer is in the form of a bushing and should fit the shaft snugly. Clean all oil-drain holes. Use a new oil-retaining plate gasket if necessary. Tighten the flywheel securely. Oil leakage at the front of the crankshaft can be corrected in a similar manner. If oil leaks from the distributor shaft, remove the shaft and renew the felt.

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114

Crankcase Breather Valve

High- and Low-Speed Engines. — The function of the breather valve, A, Fig. 6 is to maintain a vacuum in the crankcase. The valve 433.

should be removed and cleaned at each top overhaul. The thin steel disk of the breather should not lift more than 0.015 in. and should be inspected

that it is seating properly. The crankcase vacuum can be meas ured readily with a simple water manometer. To make such a measure ment, remove an oil-filler bolt, and plug in the manometer by means of a small tube inserted in a cork. A hollow bolt in the crankcase door fitted with a rubber or copper tubing connection may be used for a permanent connec tion. The vacuum should be at least 1 in. of water. If the breather vent line is so long that the required vacuum cannot be obtained a small blower may be used in the line, but it should not create a vacuum of more than 10 in. of water. to

see

Oil Change Procedure 434. Crankcase oil should be changed frequently enough to prevent excessive lacquering or gumming of engine parts. The oil change interval is dependent entirely upon the oil performance. It is suggested that the oil

The CFR-48 engine requires 3.5 qt of oil; the high-speed engine, 3 qt; the low-speed engine, 2.5 qt. An additional quart is required if the oil filter has been repacked. The oil level should be kept halfway up the sight glass, F, Fig. 1, but not above that point. On the CFR-48 crankcase the sight glass is a transparent plastic plug, item 72, Fig. 25. It should not be tightened excessively as its expansion, when hot, will seat it very firmly on its gasket to prevent leakage. be changed at least every 50 hr.

Engine Break-In

No set procedure is specified for breaking-in an engine after over haul. A period of 4 to 8 hr is suggested. However, if an engine fails to check 435.

the detonation pickup should be removed and the piston inspected for signs of oil pumping. If this is the case the engine should be run on a nonknocking fuel until operation is satisfactory.

after breaking-in,

Induction System Heaters 436. (a) The surge tank heater should be inspected periodically. It has been found that the metal casing on this heater sometimes deteriorates, forming small particles which are drawn through the intake port and which

The heater should be examined to possibility. forestall this — The mixture heater should be removed at the time (b) Motor Method. of top overhaul of the engine and all deposits scraped and cleaned from the heater blades and inner walls of the manifold. Two types of manifold and cause serious damage to the cylinder.

heater assemblies are available — the screw and the flange. With the screwtype assembly the heater must be reinstalled so that the opening between

MAINTENANCE the two prongs is directly opposite the carburetor

115

inlet, the prongs are

straight and parallel to each other and centrally located with respect to the manifold walls, and the lower ends of the prongs are 0.125 to 0.250 in. below the horizontal plane through the center of the manifold outlet. The flangetype assembly is designed to eliminate these errors. It is preferable to the older screw type, but it should also be checked when originally installed. The thermometer must be vertical and located so that the center of the bulb is at the center of the manifold, 1.875 ± 0.010 in. from the center axis of the vertical section of the manifold and 0.437 ± 0.010 in. from the flush face of the flange of the manifold outlet.

Ice Tower 437. Specifications for the ice tower and surge tank assembly are given in the methods. These should be strictly adhered to as any changes will affect the fuel-air mixture delivered to the engine. The ice tower must be kept free of sludge and dirt as improper drainage may result in water accumulation which will affect the charge to the engine. Moreover, sufficient water may accumulate to be drawn into the engine and cause serious dam

To avoid this condition, frequent inspection of the drain and bottom of the ice tower should be made. It is suggested further that a water age.

manometer or safety trap be installed to indicate this condition. All joints of the assembly should be tight so that uncontrolled air does not enter the engine. Leakage will also affect settings of carburetor fuel level.

Exhaust System 438. The specifications

for the exhaust system, Section 111, should be strictly. Back pressure and resonance affect engine scavenging, causing irregular cyclic variation. Consequently, they affect fuel ratings. For exhaust systems of the surge-tank type, open the surge-tank port and remove any deposits. Give particular attention to deposits at the mouth of the water drain pipe. If this drain pipe appears to be clogged, remove and clean it. Inspect exhaust systems using water injection for clogging of the spray holes in the brass ring. They may be blown with air or reamed with

followed

a piece of wire.

Carburetor Assembly 439. (a) The adjustable level carburetor with one-piece vertical jet is illustrated in Fig. 31. The cross section shows the float chamber and bowl assembly. The float chamber and jets are assembled as a unit. Periodic inspection should be made of the float and needle valve as deposits form on the latter causing erratic flow of the fuel and impairing carburetion. The needle valve should be removed periodically and cleaned with crocus cloth or the seat lapped with Lava soap, aluminum oxide, or similar material.

The float may become damaged or leak which will produce level. If this occurs the float may be repaired by soldering.

a rising fuel

116

JJ3S5

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117

(b) Metering jets of different sizes may be required to maintain the fuel level within the specified range of 0.8 to 1.8 in. The following sizes are usually

satisfactory: Waukesha Jet No.

Approximate Diameter

Motor

58

0.031 in.

Research

6S

0.033 in.

Method

However, differences in fuel characteristics and barometric pressure may require that jets of different sizes be used. Fuel delivery through the jets may be impaired by deposits which will be indicated by sudden changes in carburetor settings required for maximum knock. If the jet sizes listed do not give the proper fuel level and deposits are not apparent, the fault may be traceable to the vertical jet and venturi assembly. (c) The one-piece vertical jet and air bleed tube are shown at N and P, Fig. 31. These parts may be removed by unscrewing the setscrew, R, on top of the venturi body. After removing the air bleed tube, unbolt the vertical jet flange and draw the vertical jet from the carburetor body. These parts should be cleaned with acetone or a similar solvent at regular intervals. Upon reassembling, the proper size flange gasket is selected to locate cor rectly the air bleed tube in the venturi. The location and height of the vertical jet and the dimensions and concentricity of the air bleed tube must be adhered to at all times, as they are critical for proper operation of the engine. The venturi size specified in the method must be used. On the older type carburetors with the unflanged vertical jet, disassembly is accom plished by removing the setscrew, the air bleed tube, and then drawing the vertical jet through the setscrew hole. Upon reassembling, the gasket at the bottom of the vertical jet must provide a perfect seal. If leakage occurs, fuel will be drawn into the venturi around the jet and will produce erratic engine operation. To center properly the horizontal air bleed tube in the venturi, 0.005 in. copper shims for the upper end of the vertical jet and thin paper gaskets for the lower end of the vertical jet are available. (d) The selector valve should be checked periodically for scoring and fit, as leakage will allow mixing of fuels during a test. A simple test for leak age is to operate the engine on 40 octane fuel with no fuel in the other bowls. While maintaining operation on this fuel, pour isooctane plus 4 ml of tetraethyllead per gallon of isooctane into one of the other bowls. If leakage exists in the valve, the fuel will mix with the 40 octane fuel and change knockmeter

readings.

If

this condition exists remove the selector valve and

clean it with acetone. Lapping with jeweler's rouge or a finely ground cleansing powder will correct improper fit. If leakage persists, it may be due

to the end of the selector valve striking against the gasket. Ignition System 440. Either a magneto or a coil and distributor ignition system are used. The magneto generates its own current; for the coil and distributor system the primary circuit for the coil is taken from the Ignition Power Supply, or

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118

from the 110-v d-c generator connection at the back of the panel board.

The ignition system should be thoroughly inspected at each overhaul and any faults should be corrected. Coils should be tested at 2000-hr intervals. Due to the wide variety of testing equipment in service, however, it is not feasible to specify a detailed test procedure. Should the magneto fail, replace it or have it repaired by an authorized manufacturer's service be

In order to conform with Section

ignition switch should installed in the d-c line from the output of the ignition power supply.

branch.

A — Spark Timing Scale. B— Neon Tube. C — Ignition Coil. D — High Tension Cable to Spark Plug. E — Breaker Assembly. F— Cam.

FIG.

10 (c), the

G — Link to

Cylinder

for

Automatic

Spark Adjustment, (Disconnected for Research Unit).

H — Distributor

Control

Arm

Clamp

Screw.

I — Distributor

32.— IGNITION

Lock Screw.

SYSTEM.

The a-c connection to the ignition power supply should be made at the output terminal of the 115-v starting relay or at the oil pressure safety switch.

Coil and Distributor Timing 441. For the coil and distributor system the steps for setting the timing are as follows: (a) Set the piston at tdc on the compression stroke as indicated on the flywheel, and then make sure the spark indicator scale is set with the zero mark accurately in line with the neon-tube slot. If the indicator is wrong,

adjust the position of the scale, A, Fig.

32.

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119

(b) Adjust the length of the control link, G, so that the lever projecting from the distributor housing is horizontal. On the Research engine the spark advance is fixed. On the Motor engine the link is secured to the igni tion control arm which extends from the cylinder, thus permitting the spark advance to be varied automatically with compression ratio. Therefore, make the adjustment with the cylinder set at a micrometer reading of 0.625 in. (c) Rotate the flywheel backward so that the neon-tube slot, B, is oppo site the spark advance mark specified for the particular method. For the Research engine the setting is fixed at 13 deg btdc by means of a locking screw,

/, Fig.

32, on the

distributor. The setting for the Motor engine is

variable and is 26 deg btdc at a micrometer reading of 0.625 in. (d) Adjust the cam, F, to make contact at the specified setting indicated

in Paragraph (c) by loosening the nut which holds the cam to the shaft, moving the cam to its proper position, and then tightening the nut. (e) Run the engine and make the final adjustment to give exactly the specified spark advance.

Magneto Timing 442.

For the magneto system the steps for setting the timing are

as

follows : (a) Set the piston at tdc on the compression stroke as indicated on the flywheel and then make sure the spark-indicator scale is set with the zero mark accurately in line with the neon-tube slot. If the indicator is wrong,

is,

adjust the position of the scale, A, Fig. 32. (b) Turn the flywheel backward until the neon-tube slot falls on the 35deg mark. Loosen the magneto coupling and, with the breaker box fully advanced (that turned counterclockwise against its stop), turn the mag neto clockwise until the breaker points just start to open. Clamp the drive coupling in this position. is

a

fixed spark advance, no adjustment (c) Since the Research engine has of the magneto advance lever required. However on the Motor engine the secured by means of

a

is

cable linkage to the cylinder, thus permitting the spark advance to be varied automatically with compression ratio. There lever

fore, with the cylinder set at

a

opposite the spark advance mark specified for the particular method. For fixed at

13

deg btdc. The setting for the micrometer reading of

26 deg btdc at

a

is

is

the Research engine the setting variable and

Motor engine

is

is

micrometer reading of 0.625 in., loosen the clamping strap and adjust the lock nuts of the control cable to bring the arm of the magneto breaker box horizontal. (d) Rotate the flywheel backward so that the neon-tube slot, B, Fig. 32,

0.625 in. Adjust the breaker box until the points just start to open. Tighten (e) Run the engine and observe the actual operating spark position.

If

the clamping strap in this position.

MAINTENANCE

120

the engine is within 1 deg of the specified setting, make the final adjustment by rotating the breaker box. If it requires more than 1-deg adjustment, stop the engine and reset the breaker as outlined in Paragraph (d).

Spark Advance 443. Motor Method. — The spark advance for either the coil or magneto system should be checked with the engine running at various compression ratios to see that it follows the specifications in Section 6(6) of the Motor Method. If it does not, the trouble is probably due to one or more of the

following : (1)

Distributor lever not horizontal at

a micrometer

reading

of

0.625 in. (2) (3)

Backlash in the linkage. The plate carrying the breaker points being

loose.

Spark Plugs 444. (a) Spark plugs are very often the cause of poor engine operation. When the condition of a plug is doubtful, it should be replaced. The porcelain should be inspected carefully for cracks and blisters. Set the spark plug gap cold with a wire feeler gage at 0.020 ± 0.005 in. It is also good practice to put a small amount of suitable lubricant, such as graphite grease or mica lubricant, on the threads of the plug. Tighten the plug with a torque wrench set for 25-30 ft-lb.

— (b) Cleaning Spark Plugs. Spark-plug life may be increased by proper cleaning, but for referee samples a new plug should be used. Breaker Points The breaker points should be kept free of oil and adjusted so that they are aligned and in complete contact when closed. If the surfaces are pitted, smooth them on an oil stone or replace the points with new ones. A gap of 0.020 in. is specified, even though the name plate on some of the older units may state differently. To reduce the wear on the cam follower the surface of the cam should be given a very light coating of petrolatum whenever it has a dry appearance. 445.

Condenser 446. (a) Coil System. — Failure of the 4 mfd condenser results in no igni tion spark and replacement is necessary. — The condenser is built into the unit and may be (b) Magneto System. removed by first removing the magneto body cover plate. Exceptionally bad pitting and sparking across the points is a sign of condenser failure. Since it is difficult to make a satisfactory test of the condenser, it is more satisfactory

and economical to install a new one.

If

the magneto loses its or to a re

residual magnetism it should be returned to the manufacturer liable service organization.

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Neon Spark Indicator 447. Neon tubes gradually diminish in brilliancy with use and occa

sionally the flash becomes dull and hard to distinguish. The tube and the connections grounding it to the crankshaft should be cleaned. Occasionally the ignition wire may be at fault and should be replaced. If the flash does not improve, the tube should be replaced. A check should be made oc casionally to ensure that the slot in the rotating disk of the spark-advance indicator points to zero when the crankshaft is at tdc. If not, adjust the protractor scale until the slot coincides with the zero mark. Synchronous

Motor

448. The bearings of the synchronous motor, if not sealed, should be cleaned and repacked with fresh grease at 5000-hr intervals. The winding should be examined and recoated with electrician's

terioration of the insulation

shellac whenever de

is noticed.

Direct Current Generator 449. The d-c generator should be inspected every 5000 hr. The com

mutator should

be cleaned and turned down

in

a lathe

if there are signs of

uneven wear or pitting. New brushes should be installed

when their con

tact ends show uneven wear or when the voltage becomes erratic. Occasional lubrication of the bearings is necessary to insure good life. Detonation Meter 450.

No regular maintenance procedure is recommended for the detona

tion meter equipment. Improper functioning of the meter usually manifests itself immediately. The following procedure is suggested as a means of locating failures of a minor nature: (1)

Check

leads and connections

from the cabinet to the other

components. Observe through the rear of the cabinet that the three voltage (2) regulator tubes are glowing. (S) Remove chassis from the cabinet and observe that the tube filaments are lighted and the connections to the controls are secure. Suspected bad tubes should be checked by replacement or exchange.

If

the above visual checks fail to isolate the trouble, the user should refer to the Operating and Maintenance Manual furnished with the equipment for a more complete checking procedure. A service for repair of these meters, as well as component parts required, is available from the Waukesha Motor Co., Fuel Research Division, Waukesha, Wis.

Knockmeter 451. This instrument

is used with the detonation meter and requires no

particular maintenance. Erratic knockmeter behavior may

be due

to worn

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122

TABLE XI— MANUFACTURING TOLERANCES AND REPLACEMENT LIMITS FOR CYLINDER ASSEMBLY PARTS. All

Dimensions

are in Inches. Manufacturing

Replacement

Tolerances

Limits

Item

PISTON

:

Material Land Clearances: Top

0.013

Intermediate

0.006

Skirt Pin Hole Alignment,

Cast Iron

0.0025

max

to 0.015 to 0.008 to 0.0035 0.001

0.0045 0.0015

PISTON PIN RETAINERS: Free diameter after compression, min

:

Truarc Circlips

1.340

1.340

1 .390

1 .390

PISTON RING SIDE CLEARANCES: Top

0.001

to to 0.001 to 0.001 to 0.001 to

0.003

0.004

Second

0.001

0.0025

0.0035

0.0025

0.0035

0.0025

0.0035

0.0025

0.0035

0.007

to to 0.007 to 0.007 to 0.010 to

0.017

0.007

0.017

0.030 0.030 0.030 0.030 0.030

Third Fourth

Fifth RING GAP CLEARANCES: Top Second

Third Fourth

Fifth

0.017 0.017 0.018

VALVES: Stem Diameter:

Intake

0.3725

Exhaust Stem Clearance:

0.3725

Intake Exhaust

0.002 0.003

to 0.3720 to 0.3720 to 0.003 to 0.004

0.370 0.370

0.005 0.006

VALVE SPRINGS: 2.58 to 2.61

Free Length

2.45

VALVE SEATS: Total run-out, seat to guide, max. Width

. .

0.002 0.050

to 0.070

VALVE GUIDES: Intake guide slot

Parallel to center line within ±1 deg to allow

Internal diameter: Intake Exhaust

0.3740 0.3750

f lift to 0.3755 to 0.3765

0.3775 0.3785

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TABLE XL— Concluded. Manufacturing Tolerances

Item

Replacement Limits

CYLINDER: Bore: Diameter Taper, max Out of round, max Quality of surface Hardness, Brinell Wall thickness : Spark plug side Pickup side Intake side Exhaust side

3.250 to 3.2515 0.0005 0.0005 10

Top Intake port thickness: Spark plug side Pickup side Exhaust port thickness : Spark plug side Pickup side Spark plug hole depth Pickup hole depth Valve port : Concentricity to manifold

CYLINDER SLEEVE

to 20 Microinches 200 to 269

3.256 0.004

0.0025 Scored or pitted

0.250 to 0.312 0.250 to 0.312 0.250 to 0.312 0.250 to 0.312 0.281 to 0.312 0.188 to 0.250 0.188 to 0.250 0.188 to 0.250 0.188 to 0.250 0.609 to 0.641 0.672 to 0.703 ±0.031

:

Clearance on cylinder.

0.002

to 0.004

0.006

0.002

to 0.004

0.006

CYLINDER ELEVATING NUT: End clearance on sleeve Thread clearance End play: Thread, max Shaft

Turn freely 0.002

to 0.003

0.001

Loose 0.004 0.005

ROCKER-ARM CARRIER: Fit of bracket pins : Rear Center

Front

to 0.0007 0.000 to 0.0007 0.000 to 0.0007 0.000

0.0015 0.0015 0.0015

ROCKER ARMS: Bearing shaft diameter Ball seats

to 0.5005 and fit ball Loose or out-of -round

0.5003

Smooth

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