fuel line size

[justanova]

i have come to the guru's for a fuel line size recommendation from the tank to the pump and maybe a mech. pump recommendation.

the car is a 1970 chev. impala with a 700r4/2500 stall. 355 rear gears and a 26"tall tire.

the car was originally a smallblock car and it still has the small 5/16" fuel line from the tank and no return line. from what i have read, all the factory big block cars had a 3/8" line. will the 3/8" line from the tank to the pump be able to flow enough fuel to support the eng. listed below? and should I run a return line also? it also has a stock replacement style mechanical pump on it too.

the engine when driving the car hard will fall flat on its face at about 4700-5000 rpms and if you back slightly out of the gas it will catch back up for a second but still doesnt seem to pull on the top end like it should.

also if anyone wants to take a stab at a horsepower est. please be my guest.

eng. specs
402 big block
9.0:1 compression
stock closed chamber oval port heads
edelbrock performer that was gasket matched to heads
jet performance q-jet
comp cams camshaft see specs below. with recommended valve springs and degreed in per comps recommendation
comp 1.7 roller tip rockers
stock exhuast manifolds for now but headers may be in the near future.
2.5" dual exhaust through thrush turbo style mufflers out the back under the bumper. (non mandrel bent)
mallory ready to run HEI distributor with msd wires.

Part Number11-670-4

Grind Number CB NOSATLGIA LS-6H+

Gross Valve Lift0.53 0.524


Duration At 0.006 Tappet Lift276 283

These Specs Are For The Cam Installed At 108 Intake CL




Duration At 0.05 229 236


Lobe Lift0.312 0.308


Lobe Separation112



sorry for the long post but I wanted you guys to have as much info as possible.

[01somta]

I know on electrical pumps the manufacture will actually recommend a certain size line for that size of pump, so you will not burn up the pump. Do you have your mind made up on electric or mech.?

[justanova]

its on my dads car and he wants to stay with mech. I dont know maybe he's just too old school

[CarlC]

A Carter street pump with a 3/8" hardline to the pump and from the pump to the carb should serve you well. I had this setup on mine and never had problems even pushing hard on track-days.

[justanova]

A Carter street pump with a 3/8" hardline to the pump and from the pump to the carb should serve you well. I had this setup on mine and never had problems even pushing hard on track-days.

sounds good, thanks for the info, where is the best place to get the carter pump and should we run a return line to the tank?

[CarlC]

Summit will have them. It's internally regulated and no return or external regulator needed.

A stock fuel pump should also work well. They fed some much-higher horsepower factory offerings than what you are running. I don't know what fitment problems you may have with headers and a big block but the Carter has a lower section that can be re-clocked for better fitment. The stock part will not.

Personally, I would check/clean the fuel sock in the tank, eliminate any filter on the suction side of the pump, and clean the filter in the Q-jet first and see if that clears up the problem.