Cowl Induction - Flap or not to Flap
Got a completly rebuild cowl induction system. Electronics work, Vacuum works, flow valve installed with gold side towards engine and it is set up correctly.
The top flapper is not opening during heavy throttle. The 396/350hp manual trans has a slightly larger than stock cam (.571 -vs- .610). Hardly worth mentioning. I do understand that when the manifold pressure drops, that the flapper is suppose to open. The valve then allows it to shut slowly. However, it does not.
I spent a bit of time pouring over the search engine forr cowl induction problems. Didn't find any answers.
Today; I put a smaller hose (6 mm) on it and it did help. If I punch it, I can get it to raise up about a 1/4 inch as opposed to almost shutting. I'm not sure what the slightly larger hose was, but it did fit.
Any ideas how to lower the amount of vaccum coming from the intake? The hose is attached to the intake at the back on the same outlet as the power brakes. Its all stock.
If you look at my web site, you can see a pic of how it is setup.
appreciation in advance.
70 Chevelle SS 396; Manual Trans; build sheet; matching numbers; bench; fathom blue; white pearl interior; 63k documented miles.
65 Chevelle SS 283; Powerglide; Protect-o-Plate; matching numbers; danube blue; two-tone blue interior; 51k documented miles.