oz68VET

After some more spirited driving of my car I have found out I need a bigger fuel pump. Currently using a stock one. Engine performs fine when revving out one gear but if I run through the gears I run out of fuel. No lines are crimped etc, just seems I need the bigger pump.
So, after much searching I can't seem to find an answer as to if the larger pumps (edelbrock, Holley etc.) will fit? I've seem the pumps and they appear significantly larger than a stock pump. This is a big block and I only have about 3/4" gap between the pump and frame now.

Can anyone tell me if these pumps will fit, or what mechanical pumps guys are running on 500hp big blocks?

Pop Chevy

They will fit, but I think you have other problems. Did you check fuel pump pressure AT the carb ?

'75

A restricted sock in the tank can also give these symptoms.

oz68VET

Yeah, sock is clean, pipes and hoses are open. I have about 6-7psi at the carb idling. I'd think low pressure at the carb would be the same problem problem as low flow i.e. pump problem?

'75

What carb are you using? My Q-jet would do that till I adjusted the float up higher. Not saying it's not the fuel pump, just offering other options.

ddawson

I have this one on mine. No issue all the way to 6,000 RPM

https://www.summitracing.com/parts/c...make/chevrolet

oz68VET

Sorry, I should give more information! Carb is a Holley 750DP. The car was dyno'd and was still increasing power at the 6200 limiter with no A/F problems. We built the motor for 7500, I just hadn't changed the (stupid) MSD limiter chip (resistor). Put in a 7000rpm limiter and the car will rev there in 1st, or when cruising and the dropping back to 2nd but runs out of fuel if revving out each gear. The simple fuel flow calcs suggest I need 44gph for the engine, so looking I'm for a higher flow pump. I just don't know if the larger diameter pumps will fil, it's very tight down there and I can't find a schematic of the pumps with dimensions anywhere?

gungatim

can't help you on the size/fit issue, but you asked what pump others run on 500+HP big blocks. I run a stock pump in mine. no issues with not keeping up with demand. (and I'm feeding 3 float bowls instead of 2!).

I have seen people add inline electric pumps while still using the stock pump in certain setups. maybe that is an option for you?

flyeri

I've got a Holley 12-454-11 pump with no fit issues (3/4 inch or so to frame). I had to re-clock the bottom of the pump so that the fittings were on the front rather than the side. It takes 3/8' NPT fittings and if fuel supply is the problem go to a -8an fuel line from the pump to the carb.

mikem350

Didn't the L88's run stock pumps?

oz68VET

Thanks guys! It sounds like a stock pump should do it, I'm guessing mine is just worn out (it looks like it from the outside!) Great that the larger 110gph pumps (like Holley 12-454-11 as gungatim mentioned) will fit. Will get a new one.