ORIGINAL: MikeSell
I read an article in RCM about using check valves that way. It explained it this way... The tank will only pressurize to the maximum pressure found in the muffler(usually about 5 PSI). Without the valve the pressure fluctuates widely (from 0-5 PSI but only able to maintain about 2.5 through the entire cycle.)
From my experience I would prefer a constant 4-5 PSI than a transient 0-5 PSI. If the throttle in decreased momentarialy the pressure will maintain but if the throttle is lowered for more time the pressure will reduce to the muffler pressure level.
As with any change in supply pressure you will have to adjust the idle and high speed needles. It works fine with engines with draw problems.
IMO this is a not a good solution to a fuel draw problem, some form of pump would cure that type problem. It may work in one or two configurations, but in most cases would create problems.
When I tried the check valve on the exhaust pressure line and chopped the throttle to an idle from full, the pressure would cause a rich, erratic idle. Then as pressure bleed, it would smooth out a little. The mid-range would be totally out to lunch and as the fuel level decreased, the settings would change again. You'll chase your tail trying to solve it!
Cstewa, as Jim stated, give it a try, but I'm certain you'll have problems. Those Big Block Saito's will suck fuel from a tank even if it was mounted in the tail! If you have a fuel draw problem, look into some form of pump / regulator.