sumped tank issues and questions..

[Josh]

I sumped the tank in my 79 Caprice and have the outlet near the front of the tank, passenger side, lowest part of the tank when on level ground. I am using a Barry Grant pump on the framerail just ahead of the tank. The tank is stock and has no baffles. I have, at times, heard the pump try to lose it prime when turning right, mostly when the tank is down to the last 25%. I keep it more full and this is not too much of an issue. My issue is this: I get the timing set just right using dial back light and highway seat of the pants testing. A couple of trips into town later I decide to let it rip and the engine chatters like mad. Then I feel I have to re-tune everythinig and so and so on. I am wondering if I am going lean due to slosh of the fuel in the tank to the back when I go to WOT, thereby causing detonation that would not nomally be there at high RPM without undue acceleration? This is a BBC 540 so it accelerates well. Either that of the BG pump that is rated to 1200HP is wearing out?
Any input appreciated!

[go-fish]

Josh, I'm in the same boat. I am about to go to a fuel cell with foam and put the pump in it. That, or try to find someone to baffle a stock tank?

[Josh]

I know the "ideal" way to do this would be to have it baffled, but I do not race this car (maybe 1 x a year) and I do not need to overkill my needs!

[astroracer]

I think you are a long way from "overkill" with a single, offset, pickup at the front of the tank...
Without fabbing a new tank or cutting open the one you have, one option would be adding dual pick ups at the rear corners. At least under acceleration the fuel will be going in the right direction.
The better way would be to add a drag race style sump at the rear. Make the sides taller (call these self contained baffles) on the inside of the tank to trap a little extra fuel in the sump for cornering. if you make them tall enough to go almost to the top of the tank and add some "fill holes" near the bottom of the tank this would give you good fuel retention even with a low level.
Mark

[Josh]

Mark,
Thanks for the thoughts. I like the idea of the additional pickups at the rear of the tank. Is there possibility of sucking air (and losing pump prime) into the uncovered front pickup under acceleration?

[astroracer]

I would eliminate the front pick up altogether. Cap it off and run the twin rear pick ups.