Thanks for all info its appreciated. If I would go with a air gap manifold will it fit under the hood? Some people in Sweden write that the LA 360 4bbl manifold has wider channels than the 2176 performer intake is that true?
The Performer manifold is between small and large runners and ports. They designed it as a manifold that would do well on both small and large port cylinder heads. Edelbrock may have an intake that is port matched to those heads. Your best bet would be to call Edelbrock and get in contact with a tech who knows the mopar parts well.
The RPM Air Gap does have a higher rise than the Performer and likely has larger runners and ports. It's designed to work on higher RPM engines that generally run hotter internal temperatures that need the aid in air passing through the runners to cool the fuel charge.
I like the idea of making a high RPM 318. I would suggest that you look at each component that you choose for your application and study the power ranges that they are designed to work in, so that you match the components well.
So far, your idea with the heads and Keith Black flat tops is a great idea for a high RPM/ high flow engine and would do really well with an RPM Air Gap and those heads. If the ports are not exactly the same as the Edelbrock, you can always gasket match the head and intake to each other to get nice flow.
If you go with this combination, you should look into a high RPM range camshaft and a higher stall torque converter for your transmission that is in the same stall range as the power band/ range of the camshaft and intake ratings.
I would also suggest that you get the entire lower rotating assembly balanced and maybe look for a forged crankshaft to emry cloth or cut on the journals for new bearings that are matched and plastigaged. If you can get the assembly balanced on a forged shaft, that engine will really respond to throttle.
Depending on what you are doing with the car, that may change the idea of the engine. The gear listed with a high RPM/ lift camshaft is very race minded, high compression and not too friendly on mid grade or low octane fuel. You may have to do some notching on the cylinder walls to use those valves and you may have to relieve some notches in the pistons as well for valve travel, especially with a high lift cam that would allow those heads to do what they are designed to do, but it's still a cool idea for a higher performance 318. Look into Hughes Engines for a good camshaft set. Wherever you buy your cam, I would suggest using their recommended lifters and valve springs that are tension matched for the cam you choose. The cam is the brain of an engine and sort of dictates how the rest of your gear is chosen and matched to power range.
If I were you, I'd think about how often you are going to be racing with the car and think about where and how the car will mostly be used, before building an engine. Build your engine for the car's use. :toothy6:
