BF 32 Autolite

[68blk500c]

Another option if you want to use BF32's is the Autolite #34 plug. After Ford and Autolite separated in 1972, all Autolite plugs got the Motorcraft name, Autolite continued making plugs with a new numbering system. The BF32 was now Motorcraft while the Autolite version was #34, same exact plug. You can find Autolite 34's cheaper than BF32's, here's a set on ebay now:

https://www.ebay.com/itm/127812391980

Does the same hold true for the BF42 plugs??  Did they become 44??

[s2ms]

Does the same hold true for the BF42 plugs??  Did they become 44??

The BF42 became the new Autolite #35. After a while the Autolite 34 and 35 were both phased out and replaced by the Autolite #45. Never used the 45's myself but have heard they work well in a 289 HiPo, same heat range 5 as BF42 and 35, the 45's are still available.

I think the Autolite 44 might have been a successor to the 34 (same colder heat range) but it seems to be obsolete now.

[NC TRACKRAT]

A few years back, I tried a set of the AUTOLITE 45's and found that they run on the cold side and have a tendency to foul.  It all depends on your engine and how it's tuned. If yours is higher compression and/or has been bored out and tends to run hotter, they might work. Otherwise, pony up and get the BF32's.

[Royce Peterson]

Thank you all for the responses... can I ask where you've been able to find them? I have seen a set or 2 on Ebay here and there?   Scott

https://www.ebay.com/sch/i.html?_nkw=Autolite+BF32&_sacat=0&_from=R40&_trksid=p2505460.m570.l1313

[SCOTTGTK]

Thanks Royce... I'm checking these out also!

[shelbydoug]

Actually the BF32 was obsoleted and replaced with the BF42.

The BF32's were recommended for the higher compression engines and the 42's for the lower compression engines.

Either will work but what you may find is that rpm's over about 5,000 rpm's are limited by the hotter 42 plug.


I know that there is a general dislike of the Champion plug. Not that they are inferior, but because that isn't what the "Kool people" run. However, that series offers a greater heat range then most others do, INCLUDING the Autolite's.

I have that using Champions to "tune" a brand new engine helpful.

The only other plug that comes close to that "tunability" is the NGK. If you look at the actual engineering heat ranges of their plugs, it will give you an indication why. The answer is, their design, gives a wider heat range for the same engine.


BF32's have NEVER been the exact right plug for the high performance Ford engines. They have ALWAYS been on the too cold range, noticibly fouling particularly with automatic transmissioned cars used in bumper to bumper traffic, whereas the 42 is too hot and causes detonation over 5,000 rpm.

The Champion can be dialed in better as is the NGK.

[rkm]

The Autolite tech guy told me to use AR33s, and they have worked fine in my 427 Medium riser. What NGK plugs would you recommend? NGK used to advertise "copper core" which worked better in two stroke motorcycles.

Any thoughts?

[1175]

I have extra sets of NOS BF32's, BF42's, BF34's, BF35's and BF45's

Jon