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Old 10-05-2008, 07:35 PM
01somta 01somta is offline
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Default How PSI drop with FPR in rear

Well I bent up one of my SS 1/2" fuel lines today; and it went decent, my first attempt didn't turn out too well. I wasted about 10' of the 20' stick of tubing on the supply line. I really believe that the return line will be much harder to do and snaking side by side with the other line. So I got to thinking' how much fuel pressure could possiblly be lost with my FPR in the rear of the car? I know that it would be better in the front, but I think that it would look alot cleaner and I wouldn't have to run a return line the entire lenth of the car. I was think about running about 12" of line after the pump and putting the FPR on right before the transition to my SS hardline. I know that there are some concerns with doing this; fuel pressure loss due to the lenth of line and various bends from the regulator to the carb. I will have a fuel pressure guage at the fuel log on the carb not at the FPR. Needing someone with when adjusting fuel pressure. Also I realize that the vacumn port will be useless on the FPR if in the rear, but I have seen guys not running them and here is what Malory said about the vacumn port;

"While it is not necessary to connect a hose to the vacuum/
boost compensation port, it may be beneficial in some
cases. The vacuum/boost compensation port can be used
to momentarily decrease fuel pressure (vacuum
compensation) at idle and part throttle, or increase fuel
pressure under blower boost (boost compensation).
Connect a hose between the vacuum/boost compensation
port and a carburetor or intake manifold vacuum port to
vacuum index the regulator. The set pressure of the
regulator decreases about 1 PSI for every 2 inches Hg (2
inches on the vacuum gauge). Connect a hose between the
vacuum/boost compensation port and an intake manifold
boost port to boost index the regulator. The set pressure of
the regulator increases 1 PSI for every 1 PSI of boost".

I guess my main question is could I have enough adjustablity in the FPR to get the desired FP at the carb, and is the vacumn port on the FPR really beneficial? I will be running -8 an soft lines from fuel cell, filter, pump, and then 1/2" hardline length of the frame and switching back to soft lines at the firewall. The fuel pump is a Mallory 140 and has a max psi of 14, the FPR is also a mallory and is adjustable from 3 to 12 psi. Here are specs on the motor;

502 Gen VI 4 bolt main, 9:1 CR
Melling hv oil pump
Crane solid roller p/n 168601 cam .615 .636 246 254 dur @ .050,
crane solid roller lifters
GMPP 12363400 Aluminum Rectangle port heads
GMPP 12361323 1.7 alum Rockers
Edelbrock victor jr 454-R intake
Crank Ext. ballanced, nitriated, crossed drilled gm p/n 10198922
Rods Forged 4340 Steel
Pistons GM P/N 12533507 Forged Aluminum
MSD Pro-Billet Dist.
Holley 850

Sorry for the long post, but I would really like do this if it would work.

Thanks Dustin
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