Ok here is the issue for my 68 chevelle right now. I am running a383, dart pro 1 heads(about 385hp), th400. and a quadrajet set up from the carb shop. What fuel pressure should I be shooting for. I have a holley pump # 12-327-11, along with a regulator. I am experiencing noticable powerloss any time I am in third gear.
1. Should I ditch the reulator and just try running the pump??????
2. Is it a bad idea to run a regualtor with a pump that designates a regulator is not required, and has a preset shut off at 6.5-8.0psi. (Are the pump and regulator working against themselves.

Any insight would be greatly appreciated... BRIAN..

the regulator is a restriction at this point, since one is not required.

A pump designed to be unregulated doesnt put out enough pressure to work well with a regulator.

I am running my motor with the Holley #12-327-13 mechanical pump.It says to use a regulator but I am not and have no problems with it.The pump pumps 130 g.p.h. and is at 9lbs of pressure.So far,I havent any flooding problems and fuel starvation is non existent.As i said,this pump requires a regulator but I been lucky without one.

Great information, keep it coming guys.... Thanks Brian.
P.S. I adjusted the regualtor almost max psi, and definately already felt a difference. I just was always under the impression that I needed to strictly control the fuel pressure because of the quadrajet!!!!!!

I am running my motor with the Holley #12-327-13 mechanical pump.It says to use a regulator but I am not and have no problems with it.The pump pumps 130 g.p.h. and is at 9lbs of pressure.So far,I havent any flooding problems and fuel starvation is non existent.As i said,this pump requires a regulator but I been lucky without one.

What kind of carb are you running??

5.6 psi is best but 7 psi is max for q-jet.

Also,q-jets have a small floaq bowl chamber and can easilyl run dry with a higher output perf motor like yours if you dont run a larger high flow needle & seat like the GM .135 " or edelbrock .145" units.

Also if turning much over 5k rpm install a lighter f/pump rod to avoid pump arm float which will also cause fuel starvatio on top end. Dont believe the advertising that says they are only needed for 6k or above,i have seen where new pumps had pump arm flat at approx 5k rpms esp when running a stock pump on a modified motor turning higher rpms so keep that in mind too.

Lastly,remove the restrictive in carb fuel filter and install a larger inline filter as this can affect fuel flow on top end too.

In summary installing a larger needle & seat ,removing the small restrictive in carb fuel filter,and installing the lighter f/pump rod should eliminate your top end fuel starvation woes with a q-jet if thats in fact your problem.

You could simply have a partially clogged sock on the fuel pickup in the fueltank or a clogged fuel filter causing the problem too.

Scott



Scott

5.6 psi is best but 7 psi is max for q-jet.

Also,q-jets have a small floaq bowl chamber and can easilyl run dry with a higher output perf motor like yours if you dont run a larger high flow needle & seat like the GM .135 " or edelbrock .145" units.

Also if turning much over 5k rpm install a lighter f/pump rod to avoid pump arm float which will also cause fuel starvatio on top end. Dont believe the advertising that says they are only needed for 6k or above,i have seen where new pumps had pump arm flat at approx 5k rpms esp when running a stock pump on a modified motor turning higher rpms so keep that in mind too.

Lastly,remove the restrictive in carb fuel filter and install a larger inline filter as this can affect fuel flow on top end too.

In summary installing a larger needle & seat ,removing the small restrictive in carb fuel filter,and installing the lighter f/pump rod should eliminate your top end fuel starvation woes with a q-jet if thats in fact your problem.

You could simply have a partially clogged sock on the fuel pickup in the fueltank or a clogged fuel filter causing the problem too.

Scott



Scott

Thanks Scott, I have removed the bronze filter, I installed a lightweight ARP Fuel Pump Rod. I am thinking I should just maybe dump the regulator and see what happens...

I am running a holley 800 double pumper