Bearing clearances ?

Talkwrench

Talkwrench

Well-known member
What should the bearing clearances be for a 221 ; mains [2.3990] and also for big end flanged floating bearings [1.9990] ?
 
1940-model 01a- journal diameter 1.9990- bearing clearance .0017 to .0036- rod end play .006 to .014- rod bolt tension 40 ft. lbs.- main bearing journal diameter 2.4990- bearing clearance .000 to .003- crankshaft end play .002 to .006- main bolt tension 80 ft. lbs.
 
---From Ford engine repair book---
mains - .0005 to .003, wear limit .005
rod to crankpin -.0015 to .0035, wear limit .005
camshaft to bearing clearance-- .001-.002, wear limit .004
 
I've never delt with the flanged rod bearings. On the 21A rods I have then honed .001-.0015 larger than the 2.220 the factory suggests. I also increas the side clearance of the bearing to .020" and the side clearance of the rods to.008-.010 for street and .012-.015 for racing. The reason for tis is to improve oil flow, thus cooling the bearing. These numbers are proven by many laps of hard driving and an old 296 that has over 50 K on it now. Modern oil may make these number obsolute.
 
The numbers are from the 1955 Motor's manual. Coverage ranges from 1940-1955. The numbers I posted are for the 1940-model 01a- 221 cu. in. v8 motor. Harley
 
Listen to Ol' Ron. He has been building flatheads longer than I've been driving them. I started in 1962 in a 50 model. Harley
 
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