What Oil Clearance on Mains?
On Page 25 under chapter heading "Specifications" in the official Plymouth 1965 Service Technical Manual is listed this for all small/big block Mopar V-8 powerplants main bearings: "Diametral Clearance Desired .0005" - .0015" and Diametral Clearance Allowed .0025". Exception is the 426 Hemi where clearance desired is listed at .002" - 003" and clearance allowed before reconditioning .0045".
I used plastigage when building my bracket racer 273 back in the 1970's. I had a friend "polish" the crank (at a community college machine shop class) to increase clearance to the "high side" of recommended main bearing clearances of .003". My friend said it wouldn't be easy to polish the journals that much, but it worked out in the end. As mentioned in previous posts above, probably not the recommended way to do things, but I was fortunate enough to run the quarter mile a couple of hundred times without a problem.
And as mentioned already, for a street application, .0015" main bearing clearances should be fine.
On Page 25 under chapter heading "Specifications" in the official Plymouth 1965 Service Technical Manual is listed this for all small/big block Mopar V-8 powerplants main bearings: "Diametral Clearance Desired .0005" - .0015" and Diametral Clearance Allowed .0025". Exception is the 426 Hemi where clearance desired is listed at .002" - 003" and clearance allowed before reconditioning .0045".
I used plastigage when building my bracket racer 273 back in the 1970's. I had a friend "polish" the crank (at a community college machine shop class) to increase clearance to the "high side" of recommended main bearing clearances of .003". My friend said it wouldn't be easy to polish the journals that much, but it worked out in the end. As mentioned in previous posts above, probably not the recommended way to do things, but I was fortunate enough to run the quarter mile a couple of hundred times without a problem.
And as mentioned already, for a street application, .0015" main bearing clearances should be fine.
