badbird88

Ok, I'm having this problem of finding an EGR vavle for the Holley projection manifold but now that I've found the year vehicle that the EGR valve is suppose to come on originally there is 4 different EGR valves for that year.

My question is how do I know which EGR valve will work with my 300hp 350 TBI engine since the EGR valves are from a 1978 Chevy 350 truck. Of course my EGR system never has worked properly with my upgraded engine and pretty much always sets the 32 code even though all components are brand new.

Or, how much horespower will I loose if I just block of the dang thing and not worry about it? I've heard you will loose hp and I've heard you will gain hp. I'm used to the 32 code now so I'm not too much worried about it but it would be nice not to have a 32 code at all.

Any help or advice would be great!....Anyone??

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1988 TA 300+hp 350 w/ TBI and Holley TB unit,
WC T-5, 3.42 gears w/ Auburn posi. MSD 6A, edelbrock TES headers, dynomax 3" cat and cat-back system, ACCEL coil, polyurethane bushings all around, aluminum driveshaft, Mr. Gasket open air cleaner.

1993 S-10 w/ 4.3L V6 TBI, slightly bigger cam, Mild polish job and 3 angle valve job on heads, Edlebrock TES headers, Dynomax cat back, MSD 6A, ADS chip
(bought from my dad)

2000 GMC Sierra Regular Cab Stepside
285hp 5.3L w/ 3.42 gears and locking diff. (sold to my dad..no!!)

[This message has been edited by badbird88 (edited September 26, 2000).]

Eggplant Jeff

OK one EGR expert coming up :-).

First off, HP: EGR pretty much doesn't affect it at all. It does cool the combustion chamber, which can make it less prone to detonation, which can mean the computer won't yank timing, which can mean more power. But in probably 99% of cases it makes zero difference, power-wise.

Secondly, the EGR valve type. There are two considerations... First, that the valve will fit your intake manifold. They do come in a couple different shapes. But assuming they fit, I believe you will want a NEGATIVE-BACKPRESSURE EGR valve. There is a part number on the valve that looks something like:
xxxxxxxxx
xxx xxY
The "Y" may be missing, in which case it is a "ported" valve, not sure exactly what it means but I think they were primarily used on carbed cars. If the "Y" is a P, it's a positive-backpressure valve, and if it's a N, it's a negative-backpressure valve. The negative's are easy to test, also. Apply vacuum (via a vacuum pump) to the valve, if it holds vacuum (for at least 5 seconds) and if it opens when you apply the vacuum, it's working and a negative-backpressure type. The positive-backpressure types need exhaust flowing through them to open and close so they are a little hard to test sitting on a table :-).

As far as I know, all TBI's (L03s anyway) came with negative-backpressure valves. I may be wrong but no one's told me different :-). Positive, negative, and ported all operate differently so a computer that thinks it has one type will not work with a different type.

Also, the computer has a way of determining if the valve is working. On my 92 TBI (and other TBIs, I think), it uses the MAP sensor (watches to see if engine vacuum drops when it opens the valve). On some cars (mostly TPI as far as I know) there is an actual temperature sensor on the EGR valve, and when the computer opens the valve it checks if the temperature goes up. If you don't have a wire for this sensor, I would assume you don't need one :-).

I hope this helps. If you have more questions, fire away!

P.S. blocking the valve will definitely continue to give you the code. When do you get the code right now? After a few (10+) minutes of highway cruising? Or right after you start the car? Or when?

[This message has been edited by Eggplant Jeff (edited October 02, 2000).]

badbird88

I was beginning to wonder if anyone knew anything about the EGR valves! Thanks! I finally found one from a 1978 350 Chevy pickup (Holley advised it would fit). It looks like my original with the acception of the mounting base. It has no numbers on it and the part number didn't have "P" or "N" in it. There is a sticker on the top that I haven't pulled off yet so it may be under it. I guess the heat may be more noticable when I'm in stop-and-go traffic.

Thanks again!

Scott C

badbird,

What part number and brand name did you buy?

badbird88

check your e-mail.

EGV328 I think that was an American Standard or standard something. I'll check tomorrow and re-post.

Andy89RS

I just got the EGR valve I ordered from carparts.com, and I got the Standard EGV403. Did one of us get the wrong part?

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"Racing is life. Everything else is just waiting." - Steve McQueen - LeMans

305 TBI, T-5. 15.4@92 mph
Member Southern California Third Gen F-Bodies

AOL IM: Andy89RS

badbird88

There were 4 different EGR valves for that year and the guy who ordered it for me said this one was the most popular. It cost $38 also. You may have to grind the edge of the EGR base slightly at the edge that sits nearest to the IAC valve. Mine was hitting the raised edge around the EGR mounting hole on the manifold. Looks as if Holley didn't grind enough off because the block off plate wouldn't fit properly either!

I don't think it will make a difference as long as it has the correct base to mount on the manifold. I also had to grind the edge of the gasket. There is a wierd installation step about some "orfice washers". They have different sized holes and you are suppose to use the one that matches your previous EGR valve opening. Mine wasn't on the list of OEM EGR valves so I used the washer with the biggest hole in it since it was the closest to my original EGR valve orfice (OEM No. 17088125).

Here are some scanned copies of the EGV328 instructions that came with it. The pic of the EGR is what the EGV328 looks like also.