fuel pressure ? how much

[srpntlair1]

 Put up a few posts about my motor, basically 400 to 451 stroker I am running elec fuel pump at about 6 lbs pressure, If I really get on it, when I let off it wants to stall, any estimates on what I should run for pressure ?

[firefighter3931]

6 psi is fine but you need enough volume to supply the engine at WOT. It sounds like the fuel is sloshing around inside the carb when you decelerate. Make sure your float levels are set correctly. You might need to use some jet extensions if the problem persists (assuming this is a Holley carb).



Ron

[srpntlair1]

running a 650 DP was wondering if it is underfed

[no318]

running a 650 DP was wondering if it is underfed

Perhaps, but that is probably not causing the problem you describe.  If it acts up on decel. the problem is not a size issue, since it is not flowing maximum anyway.

I agree with float levels, also pump volume.  Just because pressure is good, doesn't mean volume is.  Should put out 1 pt. in 15 sec. or so.  If not, check restricted inline filter, pickup sock, too small of line, or bad pump itself.  I have seen that before on some inexpensive elec. pumps.

[firefighter3931]

running a 650 DP was wondering if it is underfed

A 650 cfm carb is definately too small for that 451, especially if you are using a dual plane intake manifold. 

I would be looking for a 750dp for that mill. 



Ron

[Chryco Psycho]

I would be using an 850 on a 451

[srpntlair1]

figured out the stalling problem, when the muffler shop did the welding on the pipes, he noticed the lines on the top of the gas tank had some cracks so helping out he looped all 4 lined back in the tank....no venting