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Author Topic: EGR aperture size for 350ci  (Read 1297 times)

Offline freppun

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EGR aperture size for 350ci
« on: June 27, 2020, 09:50:58 PM »
Switched original 305ci with 350 crate motor long block, in 1984 C-10 many years ago.
Just switched all external parts and things have gone OK, until now with a NOx  California smog failure.
Got a new EGR valve from NAPA but it has several washer sizes and I don't know which one would be the right size for my ride.
I need a size of aperture through which the exhaust gasses will flow and keep my cylinder heads cool enough to pass smog, but not too cool or too exhausty.
Internet searches have come up empty.
Any suggestions?
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Offline VileZambonie

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Re: EGR aperture size for 350ci
« Reply #1 on: June 28, 2020, 07:31:32 AM »
The valve you purchased should have a sheet for proper sizing, if not, eenie meenie miney mo. The reality of it is, you need to make sure it actually functions, meaning the passages are clear, the vacuum signal gets to the EGR valve at operating temperature on ported vacuum. Lift up on the diaphragm while the engine is running and make sure it stalls the engine too once it's installed. Once you pass the test you can simply unplug and cap the vacuum supply to the valve if you do not like having it there.
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Offline freppun

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Re: EGR aperture size for 350ci
« Reply #2 on: June 28, 2020, 07:53:02 AM »
The sheet that came with it , thought the valve had a Chevrolet part number written on it in Sharpie, only listed Chrysler part numbers.
EGR solenoid registered vacuum, when off idle. Old EGR valve, when vacuum applied, showed no change in idle RPM, let alone a stall. That's why I'm replacing it.
I don't mind having it there, but I'd like for it to function as designed.
The Chevy part number, written on the new valve, is one number off the one it would be replacing - yes the old one is the original 1984 valve - I'm beginning to think that's close enough.
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Online bd

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Re: EGR aperture size for 350ci
« Reply #3 on: June 28, 2020, 11:12:32 AM »
Hold up!  None of what you said points to the replacement being the correct EGR valve.  One part number off can make a big difference.  The supplied sheet lists Chrysler valves?  Someone may have switched parts.  Take it back to NAPA and exchange it.  What is the part number off of the original valve?
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Rich
It's difficult to know just how much you don't know until you know it.
In other words... if people learn by making mistakes, by now I should know just about everything!!!
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Offline freppun

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Re: EGR aperture size for 350ci
« Reply #4 on: June 28, 2020, 12:05:15 PM »
Original part number : 17084814
Number written on valve: 17084815
Yes, it looks like a valve that someone returned. The bag with the different ID sized washers had been opened. It may have been missing the sheet with the Chevy numbers, too.
That number may have been the one the guy, who returned it wrote as his OEM part number and not related, at all.
Had already decided to take your good advice and go back to NAPA.
I had to order the part I have, now and may have to order another. Fortunately I have a month to get my smog, and I rarely use the truck - just for hauling.
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