Wilson6t7

I recently installed a new RPM performer manifold and 670 Holley Street Avenger carb. #s 6, 7 & 8 cylinders are running very hot as evidenced by discoloration of my ceramic coated headers. These pipes have actually looked red in the top 3 - 4 inches where they bolt to the head. Timing is 10 degrees advanced with no vacuum advance. I cant see the carb being lean or more than 3 cylinders would be affected I would think. The timing cover and damper were reinstalled in original position. I have not changed anything else. Water temp is 195 with gauge probe in intake manifold. Any ideas at all whats happening? I never had any problems before this upgrade.

BSeery

Sounds like a vacuum leak. Look at the carb base gasket, and then also check the intake manifold gaskets.
Are you using the exhaust cross-over or do you have it blocked off?
Are you using a vacuum "t" or "tree" on the back of the intake to supply vacuum to anything? Cap those lines off and check your vacuum level. Anything below 13-15 at idle on a street cam is not a good sign.

markdtn

:iagree: look for vacuum leaks. Cast intakes are forgiving of improper torque sequences and torque values. Aluminum intakes are not. If you didn't use a torque wrench and the proper sequence then do it again with new gaskets. I have also heard of porosity problems with aluminum intakes here and there. Look for vacuum leaks.