EGR Differences? What are Those?
Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
EGR Differences? What are Those?
I have three EGR valves. They look the same. They all fit. But not one has the correct part number for my 1979. How are EGRs different internally with the same external configuration?
Melting Slicks
Joined: Aug 2001
Posts: 3,047
Likes: 124
From: Wichita KS
Re: EGR Differences? What are Those? (paul79)
paul79,
The Shop manual for my 1980 says the three valves differ in the method used to control how far they open.
-- Ported signal EGR - opening determined by amount of vacuum received from a ported source on the carburetor.
-- Positive Backpressure EGR - Used on most Federal, California, and high altitude engines. Valve opening controlled by vacuum from a ported source on the carburetor and the amount of backpressure in the exhaust system.
-- Negative Backpressure EGR - Used on engines with relatively low backpressure to provide the desired opening point and flow rate.
The Shop manual for my 1980 says the three valves differ in the method used to control how far they open.
-- Ported signal EGR - opening determined by amount of vacuum received from a ported source on the carburetor.
-- Positive Backpressure EGR - Used on most Federal, California, and high altitude engines. Valve opening controlled by vacuum from a ported source on the carburetor and the amount of backpressure in the exhaust system.
-- Negative Backpressure EGR - Used on engines with relatively low backpressure to provide the desired opening point and flow rate.
Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
Re: EGR Differences? What are Those? (mapman)
Thanks for the tip! I checked my 1979 shop manual and the description is there as well. It seems that I have the negative back pressure valve. And the mounting casting is different for the three so it is difficult to make a mistake.
(And for regular readers, this is an UNCRACKED #14007378 manifold ;) .)
[Modified by paul79, 10:49 AM 1/12/2003]
(And for regular readers, this is an UNCRACKED #14007378 manifold ;) .)
[Modified by paul79, 10:49 AM 1/12/2003]
Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
Re: EGR Differences? What are Those? (redwingvette)
Thanks Brian. Your comments are very much appreciated. These little restoration projects do take time and I must say my experience with the crack in the EBay manifold was very disappointing. But the subsequent 1979 #14007378 intake manifold seen below was sourced from a Forum Member from New Mexico. And it was nice and clean when it arrived. Even a functioning EGR. Just some minor pitting in the t-stat area that J-B Weld took care of very nicely. And with a coat of VHT engine aluminum and new TVS switches it is ready to go in the spring.
The cracked manifold was donated to our metal recycling program at work. However thorough my repairs, in good conscience I did not wish to see it re-sold, or even donated, given the comments expressed in the Forum.
Thanks again. Nice to know someone follows these projects!
[Modified by paul79, 8:13 PM 1/12/2003]
[Modified by paul79, 8:21 PM 1/12/2003]
The cracked manifold was donated to our metal recycling program at work. However thorough my repairs, in good conscience I did not wish to see it re-sold, or even donated, given the comments expressed in the Forum.
Thanks again. Nice to know someone follows these projects!
[Modified by paul79, 8:13 PM 1/12/2003]
[Modified by paul79, 8:21 PM 1/12/2003]
Heel & Toe
Joined: Oct 2002
Posts: 22
Likes: 0
From: Thief River Falls MN
Re: EGR Differences? What are Those? (paul79)
Hi, I am in the process of trying to detail the engine compartment and have been wondering what to paint the intake with. What is VHT engine aluminum paint and where do I get it? Thanks for any help, Dave
Race Director
Joined: Jun 2001
Posts: 16,483
Likes: 1
From: The Only Corvette in Gila Bend, Az.
St. Jude Donor '09
Re: EGR Differences? What are Those? (78 Dave)
Don't let Paul fool you, with all the cold up there he has nothing better to do than to sit around with a toothbrush, and water. And scrub that part till it shines like that...
Paint.. We don't need no paint :smash: :lol:
Paint.. We don't need no paint :smash: :lol:
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Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
Likes: 98
From: Ontario
Re: EGR Differences? What are Those? (Desertdawg)
There is a lot of truth in that comment. Tonight will be about -10F with light snow and strong winds. I am getting cabin fever. Bring on April!!
Thread Starter
Team Owner
Joined: Aug 1999
Posts: 30,995
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From: Ontario
Re: EGR Differences? What are Those? (78 Dave)
Dave,
I buy it at a local speed shop. About $5.00. If it is available in Canada it must be just about anywhere in the USA ;) . Perhaps others can point you in a direction.
I buy it at a local speed shop. About $5.00. If it is available in Canada it must be just about anywhere in the USA ;) . Perhaps others can point you in a direction.