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Big block oil pump on a Small Block

9K views 11 replies 6 participants last post by  The Big Al 
#1 ·
Who here uses a big block oil pump on their small block? I just realized the guy that built my motor last time did. I'm not sure why or what you would benifit from it? More volume? Anyway, I'm angry now because I finally got everything to put my motor back together and now I can't do any more tonight because Napa is closed and I ordered a small block pump. I guess the 5 bolts on the pump cover instead of the usual 4 should have given me a hint. Oh well at least I learned something. I also believe the shaft is shorter that hooks to the distributor when I compare it to a regular SMC one. Maybe because my block has been decked? I don't know. Anyone else have any input as to why this may be? Now I have nothing to do except sip on this fine Rum and Coke.
 
#3 ·
Do not assume the pump is a big block.
Melling makes a M99HVS pump. A big block design for a small block only.

The case will say M77, but the pressure valves are for a SBC

I have been using them for years.

Al

 
#5 · (Edited)
The Big block pump bolts onto the small block but requires a short, (5.625" long) shaft (not the same as the even shorter front sump shaft). Moroso makes one #2290 . If you are using a 400 block, you'll need to machine the pump shaft opening to 9/16".

The big block pump eats a lot of power and, IMO, isn't really necessary. Some people believe the extra teeth on the BBC pump reduce spark scatter, but I haven't seen any documentation that there is any benefit.
 
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