[rohrt]

While doing a lot of WOT testing last night, I discovered I still am having some fuel starvation issues up around 4800 rpm. It would sputter a little.

Currently have a RobbMc sender unit in the tank and 1/2 line to the front. Then a stock small canister fuel pump feeding the 1968 Q-jet by Cliff.

I want to keep a stock look as much as I can under the hood so I'm trying to avoid a fuel pressure regulator if I can. I know the 68 Q-jet did not have the best design needle and seat setup to handle much pressure so I'm wondering what my options might be?

I need to dig my HPP mags out and look for that fuel pump articular from a few years back.

I'm wondering about the large canister pumps or maybe the carter pump if the Q-jet can handle it. Just want to be able to rev to 5200 rpm.

[locomotivebreath]

No help here , but I'm very interested in opinions as I'm running a 68 cliff qjet on a warmed over 406 and hope the small pump works . I am running 1/2 lines since the body is off and a ricks tank just cuz my wife let me buy it. What is your combo ?

[ta man]

Just my opinion..the small pump won't pull half inch lines.....

[leeklm]

I suggest going with the Robb MC 550 pump. Does not require a regulator, and will be a nice addition to your 1/2" lines. Although my current car has a TANKS electric setup, my last 455/KRE/Qjet build used the Robb MC pump and was very happy with it.

[78w72]

agree with taman, the stock small canister pumps wont feed a higher hp engine to well. but if stock look is a factor you really only have one other option, a large canister stock pump. i had a stock large canister pump on my old mild 455 powered t/a back in the 90's & it suplied the fuel ok for street use with stock lines. also have the same pump on my current mild 406 t/a & it does fine for the street & even did ok for street tire track use, no signs of fuel starvation at upper mid 13 second et & 104mph.

the carter & other "hp" pumps dont look stock but i had pretty good results with the edelbrock pump on my current 467 stroker engine... on the street. but it did have starvation issues on the track once i broke into 11 second runs. that pump doesnt have return or vapor ports though but worked fine in real world street use dead headed. the carter or e-pump should work good for you if you dont mind the non stock look.

i have since upgraded to the robbmc 1100 & there is a noticeable difference in how the engine runs at WOT, will see how it does on the track very soon. i have it dialed down to ~7psi with no regulator.

[rohrt]

Thanks for the Replies.

Originally Posted by 78w72

agree with taman, the stock small canister pumps wont feed a higher hp engine to well. but if stock look is a factor you really only have one other option, a large canister stock pump. i had a stock large canister pump on my old mild 455 powered t/a back in the 90's & it suplied the fuel ok for street use with stock lines. also have the same pump on my current mild 406 t/a & it does fine for the street & even did ok for street tire track use, no signs of fuel starvation at upper mid 13 second et & 104mph.

the carter & other "hp" pumps dont look stock but i had pretty good results with the edelbrock pump on my current 467 stroker engine... on the street. but it did have starvation issues on the track once i broke into 11 second runs. that pump doesnt have return or vapor ports though but worked fine in real world street use dead headed. the carter or e-pump should work good for you if you dont mind the non stock look.

i have since upgraded to the robbmc 1100 & there is a noticeable difference in how the engine runs at WOT, will see how it does on the track very soon. i have it dialed down to ~7psi with no regulator.

I'm not apposed to the carter super street M6905 or the RobbMC 550hp pump if that is the way to go. Funny part is I'm only looking to get another 4-5 hundred RPM. Is this over kill or just the right amount of kill

Found a few good links. The first is for the HPP article I was going to look for.
http://www.hotrod.com/how-to/engine/...ac-fuel-pumps/

The author here says:
"If a customer's Pontiac engine is heavily modified, he makes another recommendation. "Modified engines producing considerably more horsepower consume more fuel. If output is above 450 hp or so, I recommend our Competition Series (PN M6907) pump. It looks relatively stock, will work with the factory Quadrajet, fits the engine with minimal modifications, and will reliably support up to 600 hp. I begin recommending an electric fuel pump and regulator setup when horsepower exceeds that point.""

As for the small and large canister it said this:
"These two particular stock-replacement fuel pumps fit similar late-'70s Pontiac applications. Containing the same pressure and flow ratings, their visual difference is readily apparent. The large canister pump was developed in the early-'70s, and was used with certain large cube and/or performance applications with an increased demand for fuel. The larger canister acts as a reservoir for the diaphragm to draw from to fill the fuel chamber when the pump may have difficulty pulling enough fuel from the tank."

Was still concerned about the psi the Q-jet can handle but the chart at the bottom shows 5.5-7psi for all of the early 60 cars.

http://www.robbmcperformance.com/pro...ontiac550.html

http://www.jegs.com/i/Carter/180/M69...pqZRoCDzHw_wcB

So $190 for the RobbMc pump or the Carter for under $90

[Squidward]

4800 is where my qjet setup started falling down. I switched to a Quick Fuel carb. I've spun it easily to 5200 on the street, but have to back down at that point. I will see once I get back to the track.

I will probably do an electric booster pump if my issue hasn't been solved.

[goatless]

I use an electric Carter Street Pump (right in front of the tank, pulling through a Robb Mc pick up) pushing up to a stock mechanical pump on the motor. My motor isn't too far off from yours, but my car is quite a bit heavier. I run mid-12s and pulls well past 6000.

[lust4speed]

We had to install a pusher pump in both the GTO and TA of Wheelspin's. Both have the RobbMc mechanical pump, and both still starved at the top end on WFO runs. We also used a Carter electric pump as a pusher, but installed a bypass complete with check valve to save wear and tear on the pump for the other 98% around town driving. So far the system has worked flawless. We did end up with just a little too much pressure up at the carb, so we plumbed the regulator right off the bottom of the mechanical pump before it went up to the carb. Unless you climb under the car, there's no way to know the fuel system isn't stock.

While there are 90° bends, I did take a small burr on the die grinder and round the inside turns as best I could. We did one car first to see if the basic system would work, and when it did pass we went back and did the other car. Prior to this Les had the standard fare 1/2" aluminum line with the Holley 150 pump and return line. So we dropped down from a max effort to a totally quiet and reliable strong street system.

As a side note the hose is all NHRA approved pushlock hose, so even if a tech climbed under the car, they would be happy. Les was running somewhere around 11.7 at 117 at one of the warmer Pontiac Heaven events. Think he had the air off, but you never know.

[Squidward]

I like that. Providing strong inspiration if or when I need to do the pusher upgrade.

[chrisp]

Carter 6907 will do the job . Do not assume that running a larger fuel line will provide more fuel , if the pump is not capable of supplying the proper volume & pressure your results will be poor .

[THOM66]

Does anyone know of a source for the Carter 6907 fuel pump? and would the 6905 pump work on a Pontiac V-8? The catalog description shows that it is for a Ford.

[rohrt]

Is the M6907 fuel outlet clockable?

Is a barbed fitting required or will it take a flared fitting?