Is it possible to have the EGR valve spring weakened to compensate for less back pressure? I noticed that the 89 Corvette has a different EGR valve but the gasket to mount it to the manifold is the same as Firebirds. Is the differance just because Corvettes have dual exhaust and therefore the EGR valve has a weaker spring for less back pressure??

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'89 Formula 383 TPI

it won't make any difference because the valve is opened by applying vacuum to the backside of the valve. the difference is probably in the size of the orifice in the valve. I'm guessing the difference is because of a different amount of air needed for the aluminum heads.

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Kyle Osterholt
Okarche, Oklahoma
ASE Master Certified
86 T/A 383 TPI
89 TTA #1002 T-top/Leather
89 TTA #1358 Hardtop/Leather
80 T/A Pace Car
73 Opel GT

I actually heard that the EGR valve needs back pressure on it to open and the vaccum is what controls it. I don't think just vaccum alone is enough to open the valve.

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'89 Formula 383 TPI

2 types of EGR.

Positive backpressure : requires backpressure and vac. to open

Negative Backpressure : requires just vac. to open.

The differences in same looking EGRs is usually the orofice size, not the spring rate.

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

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