Hey Guys, Wondering if anyone has experience with how many horse a standard Carter Fuel Pump can handle/keep up with? The Engine I’ll be putting in my 68 was Dyno’d at 405 hp and 450 lbs/ft? Will a stock 3 line pump be fine with that? Will be feeding a Holley Street Avenger 670. Having trouble finding any upgraded pumps with the vapor line on? Does a guy even need the Vapor return?
Lots of cars came without a vapor return line. The vapor return line has advantages. I think one is that it keeps the fuel supplied to the carb slightly cooler.
The strongest mechanical pumps I know of are the RobbMc brand. One of these, along with 1/2" line back to the tank should supply your engine. They are available with a vapor return option. "...Bottom "Vapor Return" Port: 1/8 NPT (metered)..."
I ran all my 455 bracket cars with factory 3/8 line from the tank, a stock mechanical pump, with a Carter P4070 elec "pusher" pump back near the tank. Only switched the elec pump on for a pass down the track.The mechanical will pull thru the Carter elec pump, for normal driving. This system worked OK down into the high 11's. My home built 455's probably had around 400hp/500 torque.
The Carter P4602RV elec pump is said to have a bypass fuel line, to make it easier for the mechanical pump to pull fuel, when the elec pump is not turned on.
"...I needed an electric fuel pump to act as a primer and booster pump to work with my performance mechanical pump. This pump was exactly what I needed and it comes with a bypass and check valve, plus it is made in the USA..."
I run the RobbMC pump. Its a quality piece of equipment that isn't stamped junk like so many of the Pontiac fuel pumps out there. Ive been thru 2 AC stock style pumps, a Holley pump, an edlebrock pump and a Carter. The RobbMC pump is so well made, you can buy any part for it you need and repair it down the road if needed. I haven't had one fail ever. I run the Pontiac 550HP Fuel Pump – PN 1006. I think the RobMC is the cheapest pump you can buy after you add up all the other junk that is going to fail otherwise. Go look at it and see for yourself.
Ended up going with the RobbMC Pump, thanks for the recommendations! Seems like one heck of a nice unit.
Installed it last week and was able to get some miles on it this past weekend. No shortage of fuel the few times I really got after it with just the 3/8†lines on car. Is a bit high on the pressure gauge though, hard to tell while bouncing all over from the eccentric, but appears to bounce between 8-11, however doesn’t seem to be flooding out carb, so might give another gauge a shot.
It is normal for the fuel pressure gauge to bounce at low rpms if you are using a vapor return line. If you do not have a vapor return line a pressure regulator me be required. If the carb your using requires a pressure lower than the pressure supplied by the pump, a non-return regulator such as RobbMc PN 1046 or 1050 can be used between the pump and the carb(s). Also, using a vapor return line with the pump will reduce idle pressure about 1 psi which may eliminate the need for a pressure regulator.
8-11 is too high, 5-6 is the desired pressure. According to Roe and Fisher, in their "Rochester Carburetors" book, Quadrajets like 4-6 PSI at Idle, any more can cause problems. Checking the gauge accuracy is a good idea. What is the pressure when you hold the RPM at 12-1500 RPM, what pressure at 3500 RPM?