The Intake Manifold Decision
The great debate; single plane vs. dual plane intake manifolds. It's something we as builders all face. Here is what I decided to use for the 454 in my '54 Belair. First off, I'll give you a little background on the engine. I was lucky to find a used 454 from a '70’s Chevy 3/4 ton truck. Once I pulled the engine and began disassembly I noticed it was stamped "HI PERF" on the side of the block. Of course being a gear head my pulse quickened. I couldn’t get the oil pan off fast enough. I smiled as soon as I spotted that forged crank and those 4-bolt mains. Score! The engine was very clean with hardly any wear, standard bore with the small “peanut port” heads. I ran the casting numbers and it came up as a GM Goodwrench replacement crate motor. So off to the machine shop it went, naturally. I had it bored .030 over with a mild dome piston and 10/10 on the main and rod bearings. I also found a set of rectangle port aluminum heads so of course I needed a good intake manifold to top it off. And so, the search began.
When trying to choose an intake you need to be honest with yourself about how and where you will be driving your car. Two basic rules apply. Most street driven vehicles benefit from a dual plane intake, while a race car, drag race, circle track and so on will benefit from a single plane intake. The dual plane basically divides the runners to supply fuel/air to specific ports in the firing order. This eliminates back pressure inside the plenum under lower RPM driving, allowing the engine to run smoother. A single plane feeds fuel/air to all ports, which creates back-pressure inside the plenum as the engine fires through the firing order. At high RPM this back-pressure actually helps the fuel to atomize inside the plenum. So at high RPM this style intake is preferred, however at lower RPM’s it hinders the idle ability. Also, most intake manifolds list a specific RPM range. The ranges listed are found through extensive research so you can trust what each company has their intake manifold rated at.
Armed with this information I began my search. I decided to go with a dual plane intake since my sleeper is going to be a street cruiser with an occasional lead foot from light to light. I chose Pt. # 3257562, Edelbrock RPM Air-Gap 2-R Intake, Rectangle Port, Big Block Chevy. Hood clearance wasn’t an issue for me so I went with the taller air gap which allows a cooler, denser fuel mixture for more power. It has a 180 degree firing order (hence the dual plane, single plane has 90 degree firing order) for good lower RPM driving. It has an RPM range of 1500-6500 that suits my cam selection perfect.
In my opinion the cut out shown above may be part of the reason this intake is listed to 6500 RPM. I bolted this intake on using Edelbrock's Intake Manifold Bolt Set. They are designed specifically for Edelbrock manifolds, and have a twelve point reduced head for easy wrench access with hardened washer included. I torqued them to 25 Ft Lbs. in the proper sequence listed in the provided instructions. For gaskets I am kind of A Fel-pro snob, probably passed on from my father since that was his gasket of choice. I used Fel-pro's B/B Chevy Intake Manifold Gaskets and then just a bead of black RTV silicone on the ends. The fit and plain finish on this intake was just what I was looking for. It complements the aluminum heads and has the aggressive look with the air gap design. Now to find the perfect carb to top it off!