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I was helping a friend on his '57 Vette, The 283 engine was rebuilt several years ago. The distributor would not seat, no matter what we did. The oil pump drive shaft was 6-3/8" long. I compared this to one I had which was also 6-3/8. Another one I have from a newer 4.3 measured 5-3/4. He went to the parts store an bought one. It was 5-3/4" and it worked perfectly.

Does any one know why the difference. I had thought they were all the same?:confused:


Thanks
Mat
 

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I had the oppsite problem a couple of years ago - installed new HV oil pump & had a terrible noise - not enough to sound like a rod knock but close.
I ended up pulling pump back out ( thinking it was in the pump ). When i compared new one to old one they were different lenghts. Reinsatlled pump with longer one & it's still running fine
 

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Oil Pump Drive Lengths

Just recently delivered a pair of 265" Corvette SB's. The 1955/1957 265" AND the early 1957 283" SB's utilized different oil pumps AND driveshafts. Later '57's along with rest of the SB's went to the M55 style pump and the slightly shorter drive. We would modify the oiling system in the blocks (cores) themselves back then. This in turn lets us use any late style, 1958 and up, cams without oiling issues.

The very early SB's had a flat area machined on the cams at the rear journal to "complete" the oil passageway to the lifter bores. You have to pay close attention to this specific area when rebuilding these units or you will have some issues. We modify the block itself at the rear cam hole to accept the later, 1958 and up, camshafts. These blocks use different cam bearings as well.

If you do any of these units and do not modify those 2 holes you MUST put the flat back on the later cams. It's much like the early BB's with the rear cam journal needing the groove, but instead of the groove the SB's need a "flat" area instead!

Thanks, Gary in N.Y.

P.S. The modification to the blocks at the rear incorporates "connecting" the 2 separate oil holes below the cam bearing surface so the oil supply is continuous behind the bearing. It eliminates the need to have the "flat" area on the cam to "open" the passage to the 2 small feed holes.
 
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