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94 Fleetwood Brougham
7,602 Posts
I was having problems with my #1407 Edelbrock when I went to high altitude (>6000 feet), even though I was jetted for it, the fuel was boiling in the carb and forcing its way through the boosters, but only at idle (70F out). I eventually put on a multiple stack carb spacer for heat and that helped, but ultimately the blockoff of the exhaust xover fixed that problem. It was on a 70 10:1 compression 455 Pontiac with a Cam Dynamics 284H cam (.480 lift, 228 @ 0.050, on a 112). Small valve iron heads with Edelbrock Performer intake.

As for fuel pressure. Are you measuring at same engine rpm? Do you have electric fuel pump or mechanical? Mechanical needs to be at x rpm, electric doesn't matter. Do you have a return on the regulator? If no return, it will eventually overpower it and raise pressure.

Even 2 lbs should live on a Q-Jet, but WOT may be an issue. Q-Jets will put up with as high as 7 lbs, but are designed around 5.
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