EGR Valve

[Pamela H.]

'74/454 with air should it have one and why can't I find it in any of the catalogs?

[William M.]

Re: EGR Valve

Welcome to the world of impossible to find 73/74 LS4 parts
Here's a picture of what it looks like. It is the round valve between the carburetor and thermostat housing:

[Terry M.]

Re: EGR Valve

And it needs to not only have the right part number stamped on it, but the right date as well. These kinds of things makes restoring your Corvette so much fun. Just keep reminding yourself that it is fun.

[Michael W.]

Re: EGR Valve

'74/454 with air should it have one and why can't I find it in any of the catalogs?

If simply you're looking for a functional replacement, any auto parts store would have one. If it's for Judging, a correct NOS example will be very rare and priced accordingly.

[Paul J.]

Re: EGR Valve

Pamela, start with e-bay. It may take a while to find one there. If it is not a Corvette only part, there are thousands of used ones in the junkyards across the Country. You should be able to find a used one at a local large junkyard or a national supplier like Desert Valley. Then it becomes a matter of cosmetically restoring it. As for functionality, I believe that you can plug it and the car will run fine. You may need to advance your timing a little if you get any pinging.

Paul

P.S. If your old one has the right part number on it, don't throw it away. Some people will still want it.

[Joe L.]

Re: EGR Valve

I believe that you can plug it and the car will run fine.

Paul

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Paul------


It might even run better but there are downsides. The car might not pass an emissions inspection if that's required where the car is registered. Also, it might not pass an NCRS PV if something like this is actually checked.

[Joe L.]

Re: EGR Valve

'74/454 with air should it have one and why can't I find it in any of the catalogs?

Pam-----

As I recall, this car is an automatic transmission. It matters for an EGR valve. Anyway, if so the original and replacement valves were as follows:

If California car (engine suffix code "CWS") original valve was GM #7041425. This valve was discontinued in April, 1978 and replaced by GM #17051841. The latter was discontinued without supercession in 1986.

If non-California (engine suffix code "CWR") original valve was GM #7049867. This valve was discontinued and replaced by GM #17051872 and the latter was discontinued without supercession in 1987.

As is stands right now, I can't find any source for a new, replacement valve for your application. There may be one but I can't find it.

[William M.]

Re: EGR Valve

Pam-----

As I recall, this car is an automatic transmission. It matters for an EGR valve. Anyway, if so the original and replacement valves were as follows:

If California car (engine suffix code "CWS") original valve was GM #7041425. This valve was discontinued in April, 1978 and replaced by GM #17051841. The latter was discontinued without supercession in 1986.

If non-California (engine suffix code "CWR") original valve was GM #7049867. This valve was discontinued and replaced by GM #17051872 and the latter was discontinued without supercession in 1987.

As is stands right now, I can't find any source for a new, replacement valve for your application. There may be one but I can't find it.

Been down this road ... there isn't one

[Joe L.]

Re: EGR Valve

Been down this road ... there isn't one

William------

That's very unfortunate because EGR valves are life-limited parts. There are two failure modes for EGR valves:

1) The pintle (plunger) becomes carbonized and sticks open or closed;

2) The internal rubber diaphragm fails

Failure number (1) can usually be easily remedied with a Dremel tool. Failure (2) is "terminal" and renders a valve permanently inoperative. However, with the pintle sealed shut, the valve can still be used as an "ornament of originality". Some folks disable these things anyway.

One more thing about EGR valves: these things are all calibrated for specific applications. The amount of exhaust gas recirculation is critical to the proper running of the engine and emissions performance. Too much and/or at the wrong time and the engine will run poorly. Too little and the engine will run fine but the emissions will be off (if that matters).

[William M.]

Re: EGR Valve

My original is still functioning, but I'm always on the lookout for a spare. Just haven't found one yet.

[Paul J.]

Re: EGR Valve

Paul------


It might even run better but there are downsides. The car might not pass an emissions inspection if that's required where the car is registered. Also, it might not pass an NCRS PV if something like this is actually checked.

Hi Joe. Even California does'nt check for an EGR valve on a 73. I doubt that anyone else does either. However, I think that there's something in Canada about it having to be there, although it does'nt have to work.

The function is easily checked, but do they actually do this in a PV? It requires removing a hose, which I thought was verbotten.

Paul

[Joe L.]

Re: EGR Valve

Hi Joe. Even California does'nt check for an EGR valve on a 73. I doubt that anyone else does either. However, I think that there's something in Canada about it having to be there, although it does'nt have to work.

The function is easily checked, but do they actually do this in a PV? It requires removing a hose, which I thought was verbotten.

Paul

Paul------


Yes, 1973 model cars in California are not required to undergo bi-annual emissions inspections. However, the state and federal requirement that all emissions control equipment be installed and functioning remains in force. It is my understanding that if a car is identified as a "potential gross polluter" by roadside sensing equipment, it can be called in for an emissions inspection.

I don't think that EGR (or any other emissions control functions) are checked on a PV. I was being a bit facetious about that to highlight the fact that there may be many non-functional systems, especially on 73+ Corvettes, that are not detected as part of a PV.

[Michael W.]

Re: EGR Valve

Hi Joe. Even California does'nt check for an EGR valve on a 73. I doubt that anyone else does either. However, I think that there's something in Canada about it having to be there, although it does'nt have to work.

Much like the US requirements varying from state to state, the same thing exists in Canada. I believe that Ontario is the only province that requires smog equipment to be present but is not tested for function.