[HWYSTR455]

Originally Posted by Torquewar

Well ill jump in,had a 1/2 aluminum line bent to stock route with a Robb Mac 550. I also nosed the car over at 100mph so went to Russell 8an from tank to carb . Got the car into consistant 11:60s and was happy.There was that question of maybe running it lean at higher speeds.? I decided to do a check late in the year with a guage and well 6psi until 4k and then 4psi dipping to 3 just above 5k.
Hell with it just bought the Aeromotive drop in sys,so we shall see whwere it goes.
Chatting with Cliff last year on the phone and he said the same thing as he has also commented on this site..build your system for a car 2 seconds quicker and dont look back.

Ok, lemme get this straight, you had a 1/2 hard line from the tank to the pump, with the 550 pump, it would nose over, and when you ran a AN8 line tank to carb, it picked up? With no other change? And you had the 1/2" pickup? Ran the same level of fuel? And after you made the changes, you hooked up a gauge and you are still seeing a drop in psi?

If I would have to guess, it sounds like you have a vent problem. You might have been sucking a line flat before you went to the AN8 line too.

Are you running a late model non-vented cap? If so, try switching to an early vented cap. Maybe also try pulling a vent line from separator and leave it open, run the psi check again.

Maybe that's some of the difference from the Pontiacs to the Chevys, the caps the Chevys use are properly vented? Just guessing there, but makes sense.


EDIT: I just looked up part numbers for a 70 GTO 455 and compared to 70 Chevelle 454, non-CA emissions, and the GTO cap is non-vented, the Chevelle is vented.

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