Converter Flash Question

[Alan Roehrich]

Originally Posted by Bobby Fazio

Is there something to be said for timing/air fuel ratio relating to how long it takes for the engine to go from a two step rev limit up to its flash point? What would rev quicker, hotter cylinders with more timing or vice versa?

Absolutely the "tune up" is huge for converter flash.

A few years ago, I had a converter built for a guy with a turbo charged Regal. It was real common for those guys to run a really sloppy low RPM tune up, and just use a real loose converter. Well, he took it to a big race, with a really crappy low RPM tune up. Of course, I hear "it won't stage, it won't build boost, it won't leave". So I ask him to look at his timing and fuel map down where it should be starting to make torque and build boost. And the damned thing is at 10.5:1 A/F ratio, and has 10-12 degrees timing, down where it has very little boost. Remember this thing has 8;1 compression. So, he can't make it work, and loses early. He gets home, and calls me again. I tell him to lean it out to 12.5:1, and put about 36 degrees timing in it. All of the sudden, it easily makes 10-12 pounds of boost, flashes to 3500 RPM. Now I hear "this thing is a beast!"

So yeah, the tune up where it flashes is critical if you want it to go fast.