Something else to do if your running a keg type magnum intake. They often have a vaccume and oil leak in the plenum really bad. If you look inside and see oil puddling or heavy oil staining you probably have the problem.

The bottom of the intake has a stamped steel cover that often is warped or not well made. Many people replace the gasket and silicone the crap out of it. I decided to replace mine with a 1/4" Aluminum plate. Hughes performance makes them for about $80 but being the cheap person I am I decided to make my own. I bought a slab of 1/4" aluminum plate from a local metal company for about $30 and trimmed it with a jig saw. It took about 30 to 45 minutes to trim it and drill the holes. After I trimmed it I placed the old plate on the aluminum one I made. Marked and drilled the holes. I reassembled it and it should be good forever.

There is a manifold mod you can do to get better performance that somebody started on mine. They did a craptastic job if you ask me. It involves removing the center divider, shortening and radiusing the runners inside the intake to provide better flow. The previous owners of my engine just butchered it and left rough edges, and uneven runners that weren't smoothed out. There was a good discussion on the mods here. but many of the pics are gone bye bye.

Here are some pics of mine. I didn't get pics of the finished mods before I bolted it up but it isn't hard.

MAKE SURE YOU MARK THE DISTRIBUTOR BEFORE YOU REMOVE IT. I marked the block in relation to the distibutor and the index of the rotor. They are not as simple as just dropping it back in if you didn't mark it. The EFI system is timed off of the distributor and the Ignition timing is timed off of the crank sensor so don't try to adjust the ignition timing by rotating the distributor.

This is a picture of the leaky, butchered manifold I had. That oily plate in the background is the cover. You are not looking at the bottom of the plate that is the top that was inside the intake. See how bad the oil leak was. The side in the lifter valley was almost cleaner LOL.


Here is the aluminum plate I installed.