BF32 Spark Plug Replacement

My car specs call for BF32 spark plugs. What are folks using as alternate plugs? My understanding is the BF32 have a lower heat range than the BF42. I see Autolite 45’s come up as replacements, are they ok to use? My engine (351W 4V M code) is stock with a 600 cfm carb.


Autolite 45’s are what i have in my 69 M code.

Runs fine here in Ohio.

Mike M.


I have used BF32’s and BRF32’s in my GT-E. No problem getting the plugs NOS on eBay.

BF32 Autolite plugs

Yep. Pricey on at $11each. I was looking for an equal or better that’s in the budget.

$11 each is a bargain. You must be on a strict budget if you can’t afford those.

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BTW the stock Autolite carburetor for a 351 is rated at 470 CFM. If yours has a 600 CFM it is already modified.

Yes. It had been replaced with a newer Holley before I got the car.

Autolite 45 is a simular replacement for the original. If you are looking to “fine tune” your motor it would depend on your climate/ Sea level, fuel type used, and driving style. Trial and error. Plugs are divided into heat ranges. If you want fuel economy during the week and power on the weekend, changing plugs is sometimes needed along with carb adjustments. 45’s offer a compromise. Perfect for a starting point. IMHO


Mine also had the 600 Holley when I bought it. Leaked like a sieve, Bogged at WOT with lots of black smoke. Found an original calibration 4300. Much better. Still has the mechanical secondary bog, but much less. I take advantage of it to allow the transmission to downshift with less wear.

If you just cruising around the hotter plug For highway speeds and racing, colder plug.


I’ve had good luck with the Denso MA20P-U.