Can't get clear answer on spark plugs

[Oldgearz]

I just read 56yblock's post on spark plugs. Seems all he got was Chinese Autolites are no good. Yesterday I searched "best spark plugs for 1954 Y-block and read JimNNN's post asking what plugs are best for the 1954 239 y-block. No clear answer there either. Someone mentioned NKG and didn't give a number. Surely someone on this forum has more definitive info for the 1954-1956 y-blocks. I understand the 54 had 14mm plugs which changed to 18mm in 55. Can someone list by year (54-56) the best plugs for these Y-block cars? Or at least the plugs you have used with good results on the 1954 239 blocks? The cross-over charts list so many choices as to be of little value. I'm currently using Autolite 4316 but seem to have slight roughness and a little hesitation. New points, condenser and timing done on my 1954 239.

[KULTULZ]

Seems all he got was Chinese Autolites are no good.

And there was good reason for that. A renowned engine builder has come across bad product and he gave a warning.

If one was to recommend a particular spark plug and for some reason it failed, that poster would be a NO GOOD SOB ...

[KULTULZ]

I am slowly moving away from autolite to ngk on the shop built engines due to having a better heat range selection with the ngk’s as well as having some brand new autolites not firing from the git go.

Now that is from TED EATON. Believe me, you cannot get a better source of info. NGK is the way to go.

Personally, I would use MOTORCRAFT (if still available) in my car or a customer's car but I am a purist). Him running a busy shop where quality counts prevents him from experimenting.

You have a stock 54 with an original 239CI DIF ENGINE? Does it still have 14mm plugs (you have to be careful here as someone might have updated the engine or at some point in it's service life, FORD replaced the 54 heads with 55 heads - common service repair at that time period)?

Here is what FORD used in 1954 -

B4A 12405-A (AL-11). You should be able to cross that to NGK.

[paul2748]

While I am not sure, the 54 plugs may be the same as the 49-53 flathead plugs since they used the larger plugs.


Do the old plugs have the washer rather than the cone shaped end? If so, that is type that the flatheads used.

[miker98038]

I’ve used NGK’s for probably since the early 70’s when they came to the US. OT engines, stock engines, highly modified high compression, supercharged (centrifugal, Roots, turbo’s), everything but nitrous. For me they just worked. They are what’s in my current Yblocks.

The original claim was a wider functioning heat range. They were what the racers where using and what my builders recommended. That’s still true. So I was glad to see Ted Eaton’s response confirm my experience. This was before offshoring our usual choices.

Find the cross reference and there you go.

[Oldgearz]

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So the NGK cross reference for the original H-10 plug lists 4:

NGK B-4H-10
NGK B4H-10
NGK PFR6H-10
NGK PFR7H-10

I assume the last three are hotter plugs (I have no idea why #1 and #2 have the same numbers). I believe the "H" refers to 14 mm plugs which I have in my stock 54 239 Y-Block. engine.

So which plug do I want? Driving will be mostly short trips. Thanks for your help with this.

[Brian54]

One of the first things I did after purchasing my somewhat neglected 54 was to install new plugs .According to the counter guy the correct NGK number is B-6L; the car has run well for the last seven years .

[Oldgearz]

Thank you Brian.