I'm looking for instructions on the center divider mods to the Edelbrock performer 455 intake. I used the search engine with no luck. Thanks.

 

Do you mean the exhaust crossover, or do you mean the divider under the carburetor?

 

Divider under the carburetor.

 

I have seen the divider cut down on lots of manifolds at swap meets. I’m not really sure why or what the advantage supposedly is?

It seems to me if it was beneficial, Edelbrock would have cast it that way.

 

Bernard Mondello posted some images and maybe a video of the modification on his facebook page a year or two ago. If you use fb, try searching his page.

 

A simple half of half dollar sized notch on centerline of the back barrels is usually all that is needed.
Same effect can be done with the Olds 3 hole carb mounting gasket when using a quadrajet.

 

I have seen just the notch in the dividers underneath the secondaries, as well as the whole divider trimmed down. Some say it promotes plenum sharing as well as adds a little plenum volume. There has been much debate on if there is anything lost with the Torker manifold and it's single plane,open plenum design over a performer or RPM, so I doubt there are any ill effects to trimming down the divider. You are essentially getting a similar plenum sharing effect as using an open spacer under the carb, without the additional height and volume.

From his facebook page mentioned above, Bernard Mondello puts his manifolds in a mill and mills down the divider, then smooths it out with a die grinder. From his post:

"On the Edelbrock performer RPM we go 1.000" deep!
On the Edelbrock performer we go .800" deep!
Thank you in advance,
Bernard Mondello Racing Enterprises"

 

I've only ever heard of milling the intake manifold divider to help an aftermarket EFI system idle properly. I don't think it's necessary when running a carburetor.

 

The need to mill a divider or not depends on the engine, the cam, the induction system, and the intended use. If milling the divider was best for every application, Edelbrock would have done it at the factory.

 

Actually Edelbrock does do it from the factory. Look at the performer RPM v. performer RPM airgap for SBC.

 

I don't know if anyone has done any testing to determine whether the modification improves performance or not. I bought the majority of my engine parts from Bernard, and he recommended the modification, even called my machine shop to let them know his specs for it. The engine's a 455, .030 over, mild cam, Edelbrock heads cleaned up by Bernard and a Quickfuel 850 carb.

 

Normally it adds hp in the upper rpm range with no loss below it.
A more important aspect is distribution. If you saw the range of EGT’s on a typical dual
plane, you’d be surprised.