Big block oil pump on a Small Block [Archive] - Chevy Nova Forum

: Big block oil pump on a Small Block


Lugnut79
8th-May-2009, 10:18 PM
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.

trip-l-jax
8th-May-2009, 10:43 PM
Now I have nothing to do except sip on this fine Rum and Coke.

Don't spill it on your keyboard, you'll be typing with your tongue:rolleyes::D

The Big Al
8th-May-2009, 11:22 PM
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

http://img17.imageshack.us/img17/3466/p1010009au.jpg (http://img17.imageshack.us/my.php?image=p1010009au.jpg)

Lugnut79
8th-May-2009, 11:35 PM
Thank you for clearing that up AL. I'm glad you said something or I would be ordering the wrong pump again.

Paul Wright
9th-May-2009, 12:17 PM
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.

Lugnut79
9th-May-2009, 09:00 PM
AL, do you know if the pickup tube is 5/8" or 3/4"? The one I took off is 3/4" and I want to know if it will fit that M99HVS pump. My pickup has been modified for my 10.5" deep pan so I want to reuse it. Thanks.

The Big Al
9th-May-2009, 09:44 PM
AL, do you know if the pickup tube is 5/8" or 3/4"? The one I took off is 3/4" and I want to know if it will fit that M99HVS pump. My pickup has been modified for my 10.5" deep pan so I want to reuse it. Thanks.

3/4 inch

AL

6NOVA4
10th-May-2009, 05:39 AM
I'd be curious to know what the power loss of a BB pump vs a sb hi vol pump.

Lugnut79
10th-May-2009, 10:01 PM
I'd be curious to know what the power loss of a BB pump vs a sb hi vol pump.

I'm sure this has been asked a thousand times. Does anyone have a ballpark idea how much more it does take to spin a high volume pump? Is it the high pressure or high volume that takes the extra power to spin?

74 hatchback
10th-May-2009, 10:07 PM
The last time i had a bigger pump like that it was a DZ 302 pump that my uncle had laying around and we used it in my first 350 engine. He said chevrolet used them in Z28's for better hi rpm oiling.

Paul Wright
11th-May-2009, 08:29 AM
I'd be curious to know what the power loss of a BB pump vs a sb hi vol pump.

The BBC pumps wastes 12 hp, the SBC pump 10 hp. My pump is about 6-7 hp. I'm going to try and get it down to 5 hp as soon as I can build my new strain gauge pump dyno.

I'm sure this has been asked a thousand times. Does anyone have a ballpark idea how much more it does take to spin a high volume pump? Is it the high pressure or high volume that takes the extra power to spin?

High volume pumps use taller gears which have more friction than the standard height gears. You can read all about pressure and volume at my tech page:

http://www.geocities.com/pcwright77/files/oilpressure.html

The Big Al
11th-May-2009, 11:47 AM
AL, do you know if the pickup tube is 5/8" or 3/4"? The one I took off is 3/4" and I want to know if it will fit that M99HVS pump. My pickup has been modified for my 10.5" deep pan so I want to reuse it. Thanks.

it should be dead on!

Al