Intake cooling
Thread Starter
Instructor
Joined: May 2011
Posts: 197
Likes: 4
From: Rochester New York
Intake cooling
Hi all,,, question: On my 78 L82 smogger, why did GM delete the rear coolant passage in the intake manifold between right and left sides, but kept the ports on the heads?
Le Mans Master
Joined: Aug 2017
Posts: 8,336
Likes: 2,810
From: Cool Northern Michigan
To delete something means it was there but no longer is.
If I understand the question correctly, there never was a passage there in the Intake.
The coolant ports in the heads (front / back) make them interchangeable, left bank / right bank.
Some of those in the racing world have made a crossover hose, usually braided stainless, from the rear of the Intake on one side to the rear on the opposite side.
Others have made hoses with fittings for front to back ports in the Intake.
Supposedly, you get better and more even cooling circulation.
Or, are you referring to the hot air ports in the head that crossover via the Intake?
Those ports do get deleted all the time by the design of the Intake.
Those ports are not needed normally, to warm-up the carb.
If I understand the question correctly, there never was a passage there in the Intake.
The coolant ports in the heads (front / back) make them interchangeable, left bank / right bank.
Some of those in the racing world have made a crossover hose, usually braided stainless, from the rear of the Intake on one side to the rear on the opposite side.
Others have made hoses with fittings for front to back ports in the Intake.
Supposedly, you get better and more even cooling circulation.
Or, are you referring to the hot air ports in the head that crossover via the Intake?
Those ports do get deleted all the time by the design of the Intake.
Those ports are not needed normally, to warm-up the carb.
Last edited by HeadsU.P.; Feb 19, 2025 at 08:54 PM.
Race Director
Joined: Mar 2017
Posts: 11,960
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From: Virginia
@gkull (RIP) made a thread on the "fix". Gen III LS engines do this, too, with steam pipes.
https://www.corvetteforum.com/forums...ig-ci-sbc.html
https://www.corvetteforum.com/forums...ig-ci-sbc.html
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Bottom line, the ports in the heads are because the 2 heads are identical and interchangeable. They have always been blocked off in the rear. At least by the Chevrolet factory.
Melting Slicks
Joined: Apr 2021
Posts: 2,729
Likes: 2,174
From: Minnesota
@gkull (RIP) made a thread on the "fix". Gen III LS engines do this, too, with steam pipes.
https://www.corvetteforum.com/forums...ig-ci-sbc.html
https://www.corvetteforum.com/forums...ig-ci-sbc.html
Thread Starter
Instructor
Joined: May 2011
Posts: 197
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From: Rochester New York
Reply
Cool, I was just wondering if it was a smogger thing or something that always was. I know that the car manufacturers were doing things to get temps up in this era to burn more post combustion gases. I have always just put stuff back together and not questioned things like this. I put a tremic 5 in it and 3 72s as this is my daily driver in the summer. I was simply out of engine and drivetrain at modern highway speeds. The engine has uncounted miles and is very tired. I'm fixing that up now.
Race Director
Joined: Nov 2006
Posts: 13,282
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From: Sunshine Coast, Queensland, Australia
2025 C3 of the Year Finalist - Modified
2024 C3 of the Year Finalist- Modified
2022 C3 of the Year Finalist - Modified
Cruise-In VIII Veteran
Cool! I run a 4 speed and never run out of engine at modern highway speeds. I just let her spin!
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Thread Starter
Instructor
Joined: May 2011
Posts: 197
Likes: 4
From: Rochester New York
That's cool, they just drink gas up there. The tremic puts the motor @ around 2300 @ 75mph. I have not calculated it but the mileage is much better. One think I figured out, if your in 5th and want to pass, just stay on the boards and pull it into 4th, the slight skip rev matches and with a little practice you can be flawless.