I built a 331 using all new parts. When ordering a distributor, I was asked if I needed a long or short oil pump drive on the distributor. I didn't know that there was such a distinction. Can anyone tell me precisely what it is about a motor combo that would require one or the other?
SoCalCruising
In my experience the longer oil pump drive shaft was used on EFI applications and the shorter for carbed appications. When I was converting my 351w to EFI the F150 dizzy came with a 1/2" longer shaft than my old carbed distributor. Because I am using an ARP oil pump driveshaft (similar to the Ford Racing/Boss 302 Unit) I had to cut that extra 1/2" off the shaft to get the dizzy to seat all the way in the block. You will only have to do this is you are using one of those two oil pump driveshafts.
Hope this reply was on point. . .
Hope this reply was on point. . .
the issue is the shaft lenght on the distributor. EFI distributors have longer shafts. Now, the problem is ARP only sells one pump shaft to my recollection.
So the usual solution is to just hack saw the end of the distributor shaft by about 1/2", there is a clear mark on the shaft where to do this.
Other option is to run the correct stock pump shaft... BUT personally I would always run the fatter, stronger ARP shaft. Cutting 1/2" off the dizzy is not a concern.
So the usual solution is to just hack saw the end of the distributor shaft by about 1/2", there is a clear mark on the shaft where to do this.
Other option is to run the correct stock pump shaft... BUT personally I would always run the fatter, stronger ARP shaft. Cutting 1/2" off the dizzy is not a concern.
Thank you for the replies. I suspected it was the oil pump driveshaft length, but did not know for sure. I am using the ARP shaft and had the distributor supplier deliver the dizzy with the shorter lenght dizzy shaft. All seems to okay, I just wanted to get some background on this.
Thanks again.
Thanks again.
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