[alanmay0]

Hello I have a 1967 GTO and live in Texas where it is hot most of the time. Thus I do not need the carburetor heated by the exhaust flowing through the intake manifold and under the carburetor. Does someone make a intake manifold gasket that blocks off the exhaust ports that go through the intake manifold? Or has anyone figured out another way to solve this problem. Trying to keep the paint on the center of the intake manifold.

thanks
alan

[Mister Pontiac]

Yes, the gaskets are available. They may help in preventing the paint from burning off of the crossover, but I don’t think you’ll see much benefit beyond that. Once the engine fully warms up and reaches temperature equilibrium, the heat will soak the intake all the same.

If you really want a performance increase and want to rid the problem of crossover paint burn, you will need to fill the crossovers with aluminum.

Hope that helps.

[WDCreech]

The block-off gaskets won't last very long. I cut some block-offs from stainless steel pancake turners and they burned through over one summer. It would be best to fill the joined center intake passage in each head with molten aluminum so you would get no exhaust reversion between cylinders. If you have enough old pistons to melt, you can fill the intake too.

[Cliff R]

Bad idea anyhow, the divorced choke will not longer work correctly, and the engine will not perform well until all the parts fully heat soak anyhow.

I would not block the crossovers at the gaskets, but it will help to block the small holes at each end of the "channel" directly under the carburetors. Although the engineers meant well with that particular intake, todays fuels don't do well with the carburetor being heated up that much and we get quite a few complaints from folks using those intake manifolds.

The complaints always come in here during the hottest months of the years, we seldom hear anything about that deal in the cooler months.........FWIW......Cliff

[Blued and Painted]

It must be quite the fireball even at idle speed being the crossover passage starts just behind the exhaust valve x 4 cylinders.
Intake temp must be quite the balancing act with incoming cool air and varying exhaust temps at different load levels.
Next set of iron heads (on the bench) think I'll try to install a 3/8 steel tube while filling the ex crossover and only connect 1 cyl per head.
I'm sure an electric choke would still be needed.

[dataway]

For better or worse, what I'm trying on mine is a SS plate cut to fit in the left side intake gasket cross over spot (68 intake) and leaving the right side open so that the divorced choke gets some heat.

In mid-68 they did away with the flapper valve on the exhaust manifold that forced exhaust through the intake, and instead went with the thermostatic controlled valve on the air cleaner snorkel to an air pre-heater on the left side exhaust manifold....which I will have installed. Since I'll never be driving the car in the winter, I'm thinking this will get things warm enough in a reasonable amount of time.

After they removed the flapper valve in 68 ... I guess the engineers just figured natural exhaust turbulence, or pressure mis-match between exhaust manifolds would move enough exhaust through the intake.

[Will]

Originally Posted by Blued and Painted

It must be quite the fireball even at idle speed being the crossover passage starts just behind the exhaust valve x 4 cylinders.
Intake temp must be quite the balancing act with incoming cool air and varying exhaust temps at different load levels.
Next set of iron heads (on the bench) think I'll try to install a 3/8 steel tube while filling the ex crossover and only connect 1 cyl per head.
I'm sure an electric choke would still be needed.

Instead of trying to finagle a steel tube in there, just drill through once the crossovers are filled.

Dave Bisschop told me that's what he does on heads where some choke function or heat is needed. Just make sure you get the angle right so it goes into one of the ports and not the head.

[HWYSTR455]

Filling with aluminum you still get heat soak.

If you want to prevent the paint from burning, do the same what folks do with the exhaust ports, paint first with some Eastwood exhaust paint or other similar product, before you lay down the color.

https://www.eastwood.com/paints/hi-t...st-paints.html

Pretty sure the POR-15 high heat paint is the same thing:

https://www.por15.com/POR-15-High-Temp_p_104.html

It's always best to etch before you paint, but you don't have to, just lasts longer if you do. Use a good quality engine paint too, I like Dupli-color ceramic.

.

[grandam1979]

I have blocked of many with the plates in the gasket set have never had one fail.

[dmac]

Why not remove the crossover on a spare manifold and fill the heads? Keep your original manifold as good as new. I've seem photos posted of some excellent looking manifolds with the exhaust crossover removed. Plus it seems to me that it would increase the gap under the manifold, keeping it cooler in hot weather. I personally like a manual choke, but I grew up around cars that had them.

[shaker455]

Originally Posted by alanmay0

Hello I have a 1967 GTO and live in Texas where it is hot most of the time. Thus I do not need the carburetor heated by the exhaust flowing through the intake manifold and under the carburetor. Does someone make a intake manifold gasket that blocks off the exhaust ports that go through the intake manifold? Or has anyone figured out another way to solve this problem. Trying to keep the paint on the center of the intake manifold.

thanks
alan

Fel- Pro # 1233.

The fiber plates my burn thru over time and you might want to consider using a better material to close it off.

[Formulajones]

I went a different direction all together as an experiment of sorts.

I switched over to a RAIV manifold with a separate heat cross over. Still uses the divorce choke and all functions like factory. Wanted to experiment with pump gas, heat soak, hot temps and now cold temps.

Did this deal back early spring, drove it all summer in 100+ temps, and now this winter we've had overnight temps in the teens. So pretty cold morning starts, but the days warm up to 60's and 70's.

I've put 6,000 miles on this setup so far and happy to say it performs flawless. Divorce choke works just as it should, cold morning starts aren't a problem, but the cross over is a complete separate deal from the intake and last summer it showed no issues of heat soak. Running straight 91 pump gas.

I've found, for me, it's the best all around solution to pump gas heat soak, and still having a functional cross over and choke.

[Will]

The paint should not burn off the crossover on the manifold with the heads filled with aluminum. The manifold is only going to get up to the temperature of the engine when it's heat soaked, maybe a couple hundred degrees or so. The paint burns off because exhaust gases are over 1000 degrees.

Never had any sign of paint burning on my intake with filled crossovers.