Exhaust Manifold Temp Reaches 700 Degrees

[AreyD70]

I have had my 57 for two years now. It runs great, but the exhaust manifolds get very hot, reaching around 700 degrees. They are the original manifolds. And the intake manifold ports directly under the carb are darkened from the heat. I've read that the intake manifold discoloration is normal for these engines. But is the heat from the exhaust manifolds normal? The car has the 312 bored 30 over with a 3/4 performance cam. Nothing crazy. It has the 3-speed manual and the Ford 4100 carb. The ignition has been replaced with an electronic distributor, still keeping the coil and ballast. I have Autolite 46 plugs in it. Any info is greatly appreciated!

[SkylinerRon]

That carb is probably a little lean now with the aftermarket cam.

A couple sizes up on the jets should help.

Ron.

[AreyD70]

Thanks Ron. I am actually going to replace the Ford carb with an original Holley that Ford had for that year. It was completely rebuilt. Do you think that may help? Also, would adjusting the idle mixture screws for a richer mix help?

[thomasso]

Sorry to butt in but idle mixture is just that.  Idle circuit is no longer in play as RPM is increased.

[SkylinerRon]

The Holley was a one year only carb. Do you know the List# of yours?

I would put 2 or 3 size larger jets in it.

Ron.

[Rancher]

"late" spark or valve timing will raise exhaust temp.