A friend of mine is using a Mickey Thompson Power Ram intake on a 409. He is running the motor on an engine dyno and is having trouble with intake reversion, when the throttle is wide open under load. The cam is a mild roller, it has 10 to 1 compression and edelbrock heads. It is a street type motor with no unusual or extreme parts. I was wondering if anybody here has had a problem like this using an intake with two separate plenums like the M/T Power Ram.
Sorry, I haven't run that manifold yet. May be hard to get a response, since they made so few of these. I'll ask guys I know that have run them. Joe Sherman told me the manifold was worth 44 HP and adding spacers and 660 Holleys was worth another 22 HP. Big plenum may like a biggers shot and a longer shot from the accelerator pumps, just guessing
I don't know anything about this. But on my Howard head GMC with a individual runner manifold and 3 holley 500 two bbls, I had to put velocity stacks on each throttle bore to cure the cloud hanging over the engine. Later I had an 1100 cfm Dominater and it came with the 4 stacks. I think that maybe playing with carb spacers may help. Or cam timing.
I have one that I have not run yet and was going to add balance tubes to the manifold and carbs both. Any thoughts? Thanks Gary
if he could swap manifolds and had no reversion with a different manifold it would rule out cam overlap and timing. Then he would know if its an intake specific ailment.
Reversion is pretty common with cross-ram intakes. https://www.google.com/search?q=cross-ram+reversion& A balance tube should help - maybe try plumbing one between the carb spacers first and see if it helps before doing anything more permanent to the manifold.
When I was a wee lad, I scrimped and saved up for a cross-ram and a couple of Holleys, for my SBC. A year-and-a-half later, I gave up, and sold it all, at a loss. One of it's principle characteristics was a halo of fuel/air mixture over each carburetor. I tried a crossover tube, too. Three different cams, didn't help, either. In my middle-age, I am convinced that these can be made to work, but the resonance needs to be tuned, which you may be able to do, by experimenting with spacers. The effective runner length and port velocity is key.
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