Forced Induction Spark plug dilemma...

[m3456y]

I just purchased a 1984 Mustang Saleen clone which has been sitting in a garage for about 10 years. After pumping out the old fuel, installing a new fuel pump and filter and a new Vortech supercharger I got it running. It runs excellent while cruising, but it breaks up and misses under acceleration. The motor appears to be a stock 5.0 with headers and exhaust, so I ordered a new set of plugs as I thought that might be the problem. I pulled out the first plug to check it and it looks like the mixture is good - nice tan insulator...BUT when I compared the length of the thread end to the new plugs I bought it was much shorter. The plugs in the engine now are Bosch Platinum HR98PY, and the plugs I bought are Motorcraft AGSF32C. If the Motorcraft plugs are correct - it would seem that the shorter plugs are why the engine breaks up under acceleration. I’m hoping for some advice.

 

[dgollem]

The plot thickens I had a set of brand new autolite 2445 copper core plugs recommend for my 1986 lying around that I bought years ago . They look different than both of your plugs. They're kind of in between. Advance auto and autozone both call for an auto lite 25, for a 1984 which looks closer to your shorter plug. maybe call vortech for thier recommendation.

 

[m3456y]

The plot thickens I had a set of brand new autolite 2445 copper core plugs recommend for my 1986 lying around that I bought years ago . They look different than both of your plugs. They're kind of in between. Advance auto and autozone both call for an auto lite 25, for a 1984 which looks closer to your shorter plug. maybe call vortech for thier recommendation.

Problem solved. Took the “long” plugs back and got the correct set for the car - Motorcraft SP-502 ASF 42P and gapped them at 28 thousands. No more misfire!

 

[dgollem]

Problem solved. Took the “long” plugs back and got the correct set for the car - Motorcraft SP-502 ASF 42P and gapped them at 28 thousands. No more misfire!

glad you got it fixed