Intake manifold gasket question

[Donald H.]

This is for a 66/67 small block L79 with aluminum intake and the choke coil setup.

My question is other than slow warm up, is there any harm in using an intake gasket that blocks the hot air passage from the exhaust manifold up through the intake?

Thanks,
Don

[Timothy B.]

Re: Intake manifold gasket question

Donald,

You may get differing opinions on this question but the heat helps vaporize the fuel mixture in the plenum. In hot weather it's really not necessary so you can wire the heat riser open which will allow some heat up to the plenum but in cooler weather the heat is your friend. Try it with the heat riser wired open first so the choke works normal, on my 300hp cast manifold that made a huge difference in carburetor temperature.

[Mark E.]

Re: Intake manifold gasket question

If you don't regularly start the car in really cold weather (say below 20-30 degrees), the minuses of this system outweigh its benefits. With the intake crossover blocked and the heat riser replaced with a spacer, you'll enjoy better performance because the intake is cooler and the exhaust less restricted. And in hot weather, fuel in the carburetor is less susceptible to percolation.

The engine may be a bit fussy the first minute or so after a cold start but it's a minor trade off. And once warmed up, it will run fine in cold weather. You may need to adjust the choke to compensate for the cooler intake.

[Frank D.]

Re: Intake manifold gasket question

Both my dual quad 61 and base motor 63 had the intake manifold crossovers blocked and the heat riser wired open, never a problem even down to 30*

[Donald H.]

Re: Intake manifold gasket question

Thank you all.