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I pulled my carb to replace the secondary butterfly tensioner spring on my new to me 79 with a 400 small block. The intake baffled me a bit as you can see the divider in the center of the intake has a bit of a valley in it. Not knowing my way around the vettes very well yet I am not sure if this configuration with a quadrajet is ok; I would sincerely appreciate everyone's help. Also attached is a picture of the gasket which concerned me as well. No telling if the previous owner installed it beat up like that or if it crumbled off in this engine or the engine the carb came from.
I suspect the intake in OPs pic is from OE L82 ... it's aluminum and it has the "snowflake" marking it as manufactured by Winters. I do Not know it the cutdown divider is OE or not.
I suspect the intake in OPs pic is from OE L82 ... it's aluminum and it has the "snowflake" marking it as manufactured by Winters. I do Not know it the cutdown divider is OE or not.
Under the coolant hose is the Holley logo as well. Curious is Winters and Holley had a relationship. My vette did come with an L48 but the guy I bought it from said the guy he bought it from bought it as a project car. Lord knows what has been done to this poor thing
Factory manifolds usually did not have the recess in the manifold.
Some manifolds had the recess. It was supposed to equalize the return pulses from the manifold and thus get a more " true" signal to the carb = thus feed the engine more accurately. .more uniform mixture...
Most people used an open manifold to carb gasket when the manifold had a recess. No center runner on the gasket.
I did it when I raced and street drove the car... helped a lot
Last edited by BLUE1972; Dec 31, 2018 at 08:42 PM.
Factory manifolds usually did not have the recess in the manifold.
Some manifolds had the recess. It was supposed to equalize the return pulses from the manifold and thus get a more " true" signal to the carb = thus feed the engine more accurately. .more uniform mixture...
Most people used an open manifold to carb gasket when the manifold had a recess. No center runner on the gasket.
I did it when I raced and street drove the car... helped a lot
Pardon my ignorance but are you saying that I might be able to get by with the spread bore by using a squared bore gasket? Appreciate you checking in on the subject! Like the one in the attached photo?
Last edited by TinCanSailor; Dec 31, 2018 at 09:52 PM.
Reason: adding a pic.
I would use the regular GM spread bore gasket but cut out the center runner as it just "flops" in the wind.
Put the gasket on the manifold and use a Sharpe to mark it .
Use a sharp x-acto knife and slowly cut tit .
The square bore gasket will hit the larger secondary's .
The cut gives the dual plane some of the advantages of the single plane, but retains the desired street manors.
Last edited by BLUE1972; Dec 31, 2018 at 10:08 PM.
I would use the regular GM spread bore gasket but cut out the center runner as it just "flops" in the wind.
Put the gasket on the manifold and use a Sharpe to mark it .
Use a sharp x-acto knife and slowly cut tit .
The square bore gasket will hit the larger secondary's .
The cut gives the dual plane some of the advantages of the single plane, but retains the desired street manors.
Thank you very much for the tech tips. I'll certainly give it a try.
Thank you BLUE1972 and my sincerest gratitude to everyone else that contributed. I bought a new gasket and cut it down as suggested. My secondary butterfly tensioner is in and took the car out for a nice drive today. No more stumble on tip in and was it nice to feel it take off. My next effort will be focused on getting it to idle down.
A great video share. Honestly when I saw how mine was set up I really thought someone Bhutan beat it to fit and painted it to match. It all makes much more sense after talking with you and seeing the pics of the contender and this video.
Get or cut down a q-jet gasket to perimeter only. Middle of the gasket is unsupported and flaps around til everything but the metal core breaks off and goes out the exhaust. Yet the perimeter was still intact and sealing.
The depth of the recess is dependent on the RPM range when racing.
I probably have the numbers in my old racing stuff. Air density gauge, Flow and vacuum + timing gauges. traction / track temp .. etc....
Maybe another day - go back racing …
In 1970 I was running high 10's. That was the top of the hill. Now a ZR1 does it from the factory .. amazing..
Glad it helped.
amazing what cars can do from the factory today but my son and I aspire to learn about the classics and I can’t wait for us to get to the point where we can make some fast passes in one of our own cars.
Last edited by TinCanSailor; Jan 1, 2019 at 06:34 PM.
Intake manifold question
