Cooler intake manifold

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Dan the man

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Does the use of exhaust heat block off plate's, lifter valley baffle work? Is there a insulting material that can be applied to the bottom of the intake manifold for a cooler air/ fuel mixture? I'm looking for budget performance modifications. Do carburetor heat shield's, carb spacers help performance.
 
Dan the man said:
Does the use of exhaust heat block off plate's, lifter valley baffle work? Is there a insulting material that can be applied to the bottom of the intake manifold for a cooler air/ fuel mixture? I'm looking for budget performance modifications. Do carburetor heat shield's, carb spacers help performance.
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Absolutely on all counts. The only "insulating" thing I am aware of for the lifter valley is the metal lifter tray. Of course with intake manifolds like the Air Gap, they are unnecessary.
 
If You get an intake gasket set that covers HD trucks , the heat crossover section has a small hole punched in it instead of being wide open, allowing some cold intake heating but greatly reduced overall. Make sure the heat riser is functioning/moving freely, or remove it.
The funny thing is, SB Mopars were notorious for the crossovers being carboned shut, heads and intake. This brings us to the angle of the "low buck" part, this made many run poorly/hesitate & took forever to kick the choke wide open/drop to base idle speed, because the carb is jetted for a heated intake & the choke spring relies on it to function.
 
Killer6 said:
Make sure the heat riser is functioning/moving freely, or remove it.
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Absolutely one of the first things one should do after buying any 50's, 60's and early 70's Mopar is check the heat riser. They usually are not maintained, are often frozen, sometimes completely closed. Talk about a restricted exhaust. The one in my 56 Plymouth was frozen shut; removing it picked up eight tenths in the quarter. (OK, from 18.6 to 17.8 - but hey, if it was worth that much on a car whose stock 277 poly probably doesn't deliver much more than 100 hp to the wheels, imagine how badly a more powerful motor could be hurt.)
 
One of the issues with a small block intake is it is a wet intake. So it will get heat from the coolant in the front. Nothing you really can do about that. So this is what I did. My heat crossover has been machined off the bottom of my stock 340 intake, but I’m not sure that matters. If part of your intake sits lower than the front or rear china walls you would need to modify this a bit. So I got a sheet of phenolic material. It has to be thinner than the air space where the cork end gaskets go. My piece is thicker, so I just machined the ends a to the right thickness. I just rtv the china walls and place it on the walls. A bit more rtv on the top on the ends and the intake goes on. No more oil leaks on the ends as an added benefit.

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furrystump said:
One of the issues with a small block intake is it is a wet intake. So it will get heat from the coolant in the front. Nothing you really can do about that. So this is what I did. My heat crossover has been machined off the bottom of my stock 340 intake, but I’m not sure that matters. If part of your intake sits lower than the front or rear china walls you would need to modify this a bit. So I got a sheet of phenolic material. It has to be thinner than the air space where the cork end gaskets go. My piece is thicker, so I just machined the ends a to the right thickness. I just rtv the china walls and place it on the walls. A bit more rtv on the top on the ends and the intake goes on. No more oil leaks on the ends as an added benefit.

View attachment 1715805807
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Interesting :rolleyes:
 
Dan the man said:
Does the use of exhaust heat block off plate's, lifter valley baffle work? Is there a insulting material that can be applied to the bottom of the intake manifold for a cooler air/ fuel mixture? I'm looking for budget performance modifications. Do carburetor heat shield's, carb spacers help performance.
Click to expand...
Yes, the lifter baffle plates work. You’ll need to clearance it before final installation. A die grinder makes short work of this.
There are heat reflective paints. The problem (in my head at least) is finding one that is heat resistant and oil resistant. Glyptol (sp?) comes to mind.
The exhaust heat cross over port can be shut down with a simple metal plate and a solid gasket covering the port from the head to further block the heat.
Use a lower temp thermostat. Take out the stock 180*/190* for a 160* thermostat.

Carb heat shields also work well. Start with a thick crab gasket. These by themselves are very good. There about .300-350 thick depending on the maker. Spacing the carb up can help very well with heat. It can also help with the air/fuel distribution.

Shields are cheap and/or easy to make. For a Holley, there excellent since the fuel bowls run over the intake fire and aft collecting a lot of heat. There also available for the Carter type. And as said above “Phenolic Carb Spacers” do indeed help a bunch.

Make sure your tune is spot on. Carb and distributor.
Use a cold air induction set up. Running an open air cleaner under the hood is just sucking in hot air. Your killing HP this way. What’s better? 90* fresh air in the summer or 250*+ under the hood? While your at it, chill the fuel. Wrapping the lines is one method, using a cool can with ice is another.
 
Yep, here’s the plenum. I bought it like that. I didn’t blast it, it was almost like an epoxy primer, very tough. Wasn’t sure if is was coated.

D743B285-C847-4AD7-AA27-D11D7293736E.jpeg
 
I got a Speedmaster air gap aluminum intake last Black Friday for under $150 to my door... That's only about 6 weeks away.. hopefully again this year..
 
Whoa! SOMEONE knows what there doing on that intake.
I’m glad you showed the bottom because I was wondering how the heat shield circumvented the protruding part of the bottom of the intake. I didn’t understand how it was lying flat. Now I do.
 
B/RB are dry intakes with a bathtub intake gasket. Just insulate the carb, intakes need a little heat..ask a VW guy. IDK if all that is worth anything, but the carb insulator plate does help a boiling dry carb at shutdown. Some Imperials had a big wad of fiberglass under he 440 intake.
 
Good point. What intake are we working with here?
 
Does it work? I have no idea, but because the intake is what it is, I figured it couldn’t hurt. Over the years looking at fuel staining on the floor. I would say it helps a bit. Stains right under the carb in the pitted area, then it really tapers off about 3/4” into the port in a “v” shape.
 
True, but if it was an air gap. Thats the solution.
 
I think even leaving the cross over intact, you could just make a sunken living room/pit to clear the cross over. It’s the best way I could describe it. Cut a square out to clear and space it down and bolt another piece of phenolic over the square.
 
I would also consider the climate where you live before completely blocking off the exh xover. You do need some heat in the intake to vapourise the fuel for a street driven car. It is reqd for good mileage AND good distribution.
I live in a very mild climate. So I often block off exh xovers with a steel plate. For somebody who might live in a country area where they have 0* C in winter, I drill a 1/2" hole in the block off plate to allow some intake heating.
 
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