Is the EGR Valve really needed on a slant 6?

No! Out here we don't have to go through emissions so I run with out it and the OSAC. My engine performance is much better with out it.

You can flip it over to block the port or order the block off plate and gasket from the dealer. It cost me about #6.00 for both parts.
# 3671447 lists for $5 Dealer item, p/n 3671 447, used with standard EGR valve gasket p/n 4173 167

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Aggressive Ted

http://cid-32f1e50ddb40a03c.photos.live ... %20Swinger


74 Swinger, 9.5 comp 254/.435 lift cam, 904, ram air, electric fans, 2.5" HP2 & FM70 ex, 1920 Holley#56jet, 2.76 8 3/4 Sure-Grip, 26" tires, 25+MPG

About 20 years ago I did extensive testing with my 1bbl '75 /6 w/ & w/o EGR; mileage was absolutely identical. I wired up an electric control to control it and found that turning it off at full throttle felt like adding 2 cylinders; leaving it off tended to cause pinging at highway cruise, and turning it on 100% (applying full manifold vac to the EGR) just before I turned the car off prevented dieseling.

I built a steel box mounted near the radiator support containing 3 electric solenoid valves and put a DPDT w/ centeroff switch under the dash, so I had EGR-normal|EGR-100%|EGR-off positions.

If the factory EGR vacuum amplifier had been working right, it ought to disable EGR at WOT automatically. I scrounged a couple of spares, but they all did the same and didn't dump EGR vacuum entirely at WOT. I then saw that JCWhitney sold a gizmo to help with this problem, but they had sold out by the time I saw it.

I also had a '73 with the same setup; when I got it I found that the EGR had failed closed long before and nobody noticed.

In short, if your EGR system is working exactly as the factory intended, it costs nothing to leave it be and it does reduce NOx emissions. It it isn't working right, well, I've never tried to fix the vac amp, but I suppose it's possible. If it's working right, the only thing you'd probably notice is a decreased manifold vacuum at highway cruise.

New EGRs are so expensive, if it brakes, disable it. All early slants did good without it. I just disabled mine. So I would say no, EGRs are not needed on slants. Same with those horrible OSAC valves .



Yea, I know it looks cracked but I assure you, it does not leak.

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'74 Duster 225 Super Six w/904
14" Cragar SS wheels