Carb heat shield on cast iron intake?

[skokie]

Is a carb heatshield necessary on a cast iron intake for either a quadrajet or holley?

Thanks

[JimKshortstep4x4]

If your engine has the manifold where the exhaust passages run under the carb you will need a shield. (If the manifold has a groove between two holes in the front).

Otherwise under normal driving you don't need it.

Jim

[skokie]

Jim
How can I tell what ports are what? I can post a pic later tonight of the intake.

Thanks

[Stocker]

I replaced my stock cast iron manifold (with exhaust crossover) because it cracked, but it had no heat shield when I bought it (in 1977), nor did I have any problems with too much heat in the q-jet. Wouldn't a heat shield prevent the exhaust from heating the choke mechanism - which is the reason for the crossover to be there?

[JimKshortstep4x4]

This is a pic of a manifold that needs a heat shield. It is a BB Q-Jet manifold but older small blocks had the exhaust holes and groove under the carb. If your manifold does not have the holes and groove in front than you don't need a heat shield.

Jim

[grayw0lf]

You know, you can always pick up a nice used Edelbrock or similar aluminum intake on Ebay for around $40-50.

[skokie]

Looks like I need to use one. I already have one but I am not sure its the correct one. I will do a test fit and see.

[Stocker]

My intake didn't have that passageway across and ahead of the carb. It's been quite awhile, but I seem to recall an internal exhaust passage going across and through the manifold.

[JimKshortstep4x4]

Stocker,

They quit making manifolds with the grooves in them in the late 60's. The holes pictured in the groove go down into the exhaust passage that you are thinking of.

We tap the holes with a 3/8 npt and screw in pipe plugs, (flush style). The holes tend to plug and there is a good chance of an exhaust leak under the carb when the holes are not plugged.

Jim

[1978steven]

This is my first post on the forum and I think this intake question might relate to something I have been working on. I have a 1971 Chevy and I was getting it ready for winter driving. So I was pulling out the stuck open thermostat, that has been in it more than likely from the factory, when both bolts holding the water neck on snaped. So I pulled the intake to take it to work and get the bolts out. I got the bolts out and decided since the intake was off I'll clean it up paint it and put back on. Well, the heat sheild under the carb on the bottom of the intake was packed full of carbon build up. I am assuming this heat sheild I'm talking about is the same as the one in question above? My intake does not have the grove cut in it like the pictures above.

So, is it safe to remove the shield to finish cleaning the intake up?

Thanks for the help,
Steven

[GMC AMI]

With this intake the heat shield is very important. The thin metal shield is shaped just like carb. gasket. Without this the regular gasket will burn out
and cause an exhaust leak in a short while. The port helps warm up the gas
sooner to help old ROCHESTER carbs. I never saw one on a Holley. If they did
it has to be for a spreadbore pattern.

Welcome to the board 1978steven ! The shield in ? goes on the top of intake
under carb.

[Stocker]

Originally Posted by JimKshortstep4x4

They quit making manifolds with the grooves in them in the late 60's.

Ah, that explains it! Thanks for the info!

[1978steven]

My Bust!

Thanks for the clearification Mike Files.