spark plug gap closed on two plugs, what causes this? Options

[siverson]

hi - quick question from the garage. cdi box died on my six. got replacement and car starts right up (good). but runs like crapola right away. pulled the plugs and on two the electrode (term?) is no touching the plug.

is this why my cdi boxed died?

or is this a result of it dying?

or?

plugs were 1k miles old. cdi box was 46 years old.

[siverson]

Interesting, thanks for the feedback.

I don't think the plug length is the issue. The plugs were installed by the shop that built the engine and they use them all the time.

I also had several other new plugs in the garage are various brands for Porsche six cylinder engines, and they were all the same length.

So, just to test, I installed a new set of FR5DTC plugs. They aren't the best for this 2.0 engine (they are correct for the 964 3.6) but everything runs and sounds fine. Vrooom. I've ordered a set of WR5DC (what CDI box mfgr/PartsKlassik recommends) that I'll replace these with.

The tach seems more bouncy than normal with the CDI box, but I'll take a look at the points (or maybe replace with Pertronix).

I'll have to hook up my Air/Fuel ratio meter to see whats up. A boroscope would be nice, but I don't have one... Hmmm...

A piston hitting a spark plug on high rev doesn't really make sense to me either, but I also have WAY less experience with this stuff than brant.

-Steve