any 400 s/b experts care to chime in on this one

[Guest Anonymous]

Hey guys, heres the issue. im in search of the correct oil pump shaft for my 400 according to Jegs,Summit catalogs andevery other parts book i have seen their pump shafts with all steel collars etc. fit ALL s/b chevys. well i noticed an asteric beside the Moroso brand pump shaft and it says for 400 pump shaft end must be machined to 9/16 ?? also someone told me the mid section needs to be narrower for the 400 to clear the larger crank main on a 400 ?? really confused on this one when i primed up motor before initial statup there was excessive wobble in the priming device Helpppppp me out on this one Please

[Peternell]

By no means do I consider myself an Expert, but here "B What eye no"

 

I'm building a 406 so I do have some insight on this. Due to the larger mains on the 400's, the shaft is narrower in the mid section. I have purchased a inexpensive oil pump shaft w/a steel collar that does fit all SBC. The shaft is narrower in the mid section to accomidate the 400 but this in no way effects use in the 265-350 blocks.

 

I've got an extra stock 400 oil pump shaft I'll send you for the cost of shipping (probably a couple of bucks) E-mail me off line if interested, otherwise just look at the photos and if the shaft is narrower in the mid section, well there you go. You might search E-Bay also, thats where i got mine and it was a melling shaft for around $10 including shipping.

[grumpyvette]

Peternell

is correct the 400 must use the 2 diameter oil pump drive shaft to provide clearance for the larger 400 main bearing size as the standard single diameter drive shaft will bind against the block when the distributor is installed, this causes the distributor gear and the oilpump to wear at a very high rate if you do manage to ge it to work but in most cases something breaks fairly fast.