Have you tried both? What did they look like? I personally would think the BF42 would be better. It would clean up a little better than the BF32 and wouldn't foul with the low 9.5:1 compression. The 32 would be too cold. I run the ASF42C in my 11:1 compression cleveland and its just right. The first number on Motorcraft plugs is the temp range and the second is the tip style.

 

BF-32 have been discontinued for over 15yrs now
When the plug manufacturers went to Copper core construction of the spark plugs it allowed the plug to operate over a wider heat range.
This caused an overlapping of the plug heat ranges and a discontinuance of many plug numbers The BF32 was one of those
The current BF42 according to Autolite/Motorcraft covers both heat ranges of the BF32/42 plugs

 

Has 9.5:1 comp, headers, tunnel ram with 2 450 Holly's

Run a hotter plug to start and change only if the read is too hot...I'd also recommend a MSD and a good coil...dual quad tunnel rams are notorious for loading an engine up, especially a little one like yours with a stock CR...

 

What are the indications of your plugs being too hot?

Thanks,
John Thomas

 

Most service manuals have a plug reading chart...the Haynes manual which came with my D-coder does....

Symptoms...blistered white insulator and erosion of electrode materials; absence of any deposits...

 

Greg
Checked with my local Napa, they only have BFS-42C not the BF-42C. Will these supression plugs work o.k. or should I stick with th BF-42c's?
Thanks
Dave

 

Go with the BF-42c's. That would be a good heat range. Being winter is coming and seen you were in OHIO I would difinately not run the 32's. It was 21 degrees here where I live in VA. this morning so i know it's cold in up there in OH. Jim