Modified Pontiac Intake

[willieb]

I recently asked this question of Cliff on Performance Years website but am unable to access my account right now so thought I would try it here.

I modified a stock 1969 Pontiac Intake in a way similar to the one in Jim Hands book, as well as pictures Iv'e seen of Cliff's.  I removed the exhaust crossover, separated the water crossover, removed material between the secondaries, opened the primaries to the secondaries but kept them separate from each other.

I forgot to mention that I did have a stock 1969 intake on the original 400 in a 1968 GTO and it ran great from idle to WOT (with a qjet rebuilt by Cliff).

Now with the modified manifold it stumbles a little from a stop but runs fine other than that.  I was wondering what I might be able to do to correct this.


Thanks for any help.

Bill

[Cliff Ruggles]

They can be sensitive to removing any of the divider beyond a very small amount between the secondaries.

Which gasket are you using under the carb, fully open, 4 hole, etc?.....Cliff

[willieb]

Fully open, to match the manifold.

[willieb]

I should clarify, it is open between the secondaries and front to back between primaries & secondaries, but closed between primaries.

[Cliff Ruggles]

Thanks for the pics.  I'd install a full divider into the cut out between the two sides.  Pretty easy to make one from a flat piece of aluminum.  We've fixed quite a few of them over the years.....Cliff

[willieb]

Cliff,

Thank you for taking the time to help me with this.

Bill