Had a a massive flat spot, more like a bog Options

[michel richard]

I have indicated elsewhere that I used to run Mechanical Injection on the 2.2E engine in my 914. I switched to PMO carburetors because I had a huge flat spot, actually more like a through, a bog, an abyss, a souse hole, or a black hole, between 3,000 and 3,800 rpm, especially at WOT.

When the PMOs went on, I still had the bog, so I was massively disapointed.

Early this afternoon I made arrangements with my main mechanic man, and we went for a test drive. Sure enough, the abyss was still there. He felt that it was probably ignition related.

Back at the shop, he started fidling with a strobe light and reving the engine and figured out that the ignition was snapping to 72 degress advance between 3,600 and 3,800 rpm ! His immediate thought was that MSD box was causing the problem.

I drove back home and wired in a Bosch CDI unit that I got as part of my Jon Lowe project purchase . . . and that solved the problem. Final diagnostic: bad MSD box.

Moral of the story is: a lot of things that can look induction related to the amateur mechanic, are actually ignition. Make triple sure your ignition is 100% up to snuff before you start making big injection or carb changes.

Hope this experience can benefit others.

Michel Richard