EGR ?

By cooling down the cumbustion temps, you will reduce the willingness to ping. If you are not pinging now, with a functional EGR valve, you would likely be able to advance your timing and get better mileage and performance. I'd do it. I doubt you'd have to re-jet, in that the carb should have the proper jets for a functioning EGR valve.

In my day, we didn't have no *FANCY* _E_ _G_ _R_... By cracky, we didn't even have no *FANCY* cat-a-lytic converters or _mufflers_. We dumped raw, unmuffled exhaust gasses into the air and breathed deeply of them in-between puffs off of unfiltered Lucky Strike cigarettes and shots of corn whiskey chased with tequilla and WE LIKED IT! Our engines sucked in air and fossil fuel and BURNED it and spat out nasty by-products and we absolutely LOVED it. :-D

EGR Theory. , mostly cut and pasted from sources like GM, Niehoff, etc. EGR serves one purpose and one purpose only. That purpose is to reduce Oxides of Nitrogen (NOx). Undernormal combustion, Nitrogen(N2)Oxygen (O2) in the air and Hydrocarbons (HC) in the fuel combind into water(H2O) Carbon dioxide (CO2) and the Nitrogen remains unchanged. Under very hot combustion temperatures, the Nitrogen reacts with the other two byproducts and forms Nitrogen oxide (NO). After being released into the atmosphere, it picks up another Oxygen and becomes Nitrogen dioxide (NO2). In the presence of sunlight, it combines with other compounds like Hydrocarbons and forms Smog. Since exhaust gas is inert (very stable) it doesn't burn again. So by being introduced into the combustion chamber, it will lower combustion chamber temps enough so that the Nitrogen doesn't react with the other compounds and is passed unchanged out the tailpipe thus not contributing to smog.

Since exhaust gas doesn't burn, it doesn't exactly help with combustion. It does, however, prevent pinging at cruise or light throttle acceleration. If It pings under these conditions, but not under hard acceleration, hook it back up.

The old ones did, but the new systems open at all kinds of crazy times. Something to keep in mind when outfitting newer engines to old vehicles. The

99 Vortek we are putting in a Jeepster will have all of the smog crap except for the cat.

the 1996 LT-1 Chevy has EGR, and so does the last TPI system made in 1991.

Chris

I don't imagine that an inoperative EGR is going to raise under-hood temps all that much, but I'm not an automotive engineer. I could be wrong. Do yu have all the missing pulsed AIR rail ports on the exhaust manifold firmly plugged? I'd guess that exhaust leaks would raise temps more.

Anyway, if you decide to replace the EGR it might be good to know that -- at least for the one that I bought from a large national retail chain for my `79 CJ-5's 258 -- they come with an assortment of orifice washers and a key chart. They want you to match a part number on a tag on the EGR to one on the chart and then select the properly sized orifice from that. Again, in my case, the tag had been paper and faded a dozen years ago, no way to figure out which orifice to use. I ended up using the sized shim that was under my old EGR and tossed the baggie of washers.

I'm hoping that that was a good thing.

The air tube holes are all plugged with bolts, and I never have had any sign of a leak. All of the emissions stuff was removed by the prior owner(s). Fortunately its passed emissions the past 3 years. They said it burned cleaner then a lot of new cars, go figure. Now its exempt. Funny time to be thinking about putting emissions stuff back on. Any way I think I'll give a try. I need a small project. Far as I know I just need the CTO some vacuum hoses and the EGR. I've found some vacuum diagrams at

GaryZ