VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 Spark plugs

I’m going to replace the 25+ year old plugs in my 33, as it’s running very rich. Currently there are AC Delco 43’s in place, I plan to jump up to 44’s. My local Auto Parts store has AC 44’s, but all options have various letters following the 44 (44T, 44TS, etc.). Are these ok to use? Any I should avoid?

They’re going on my 33 1.5 ton truck, 207. Plan to gap them at 28-30

Thanks,
Adam

The AC 43 is a very cold heat range spark plug. It was recomended for heavy truck high speed use,
The only general heat range today is the AC45. I have used them in all my cars including my 1934 with good results,
The 44T is not for your engine and does not replace the 44.

Thanks - I’ll jump to 45, then. 43’s we’re placed in 25+ years ago by my father, he did not know what needed to be placed in.

What I’m hearing is I need AC 45’s - with NO lettering following the number. Looks like my local parts store have ACR45’s - will those work?

I would not use the 45S which has the extended tip...........actually it should be the AC R45 - R is for a resistor type which all are today,

And "T" stands for a tapered seat (used without a gasket/washer) and of course can not be used in any engine with flat seating surfaces.

Thank you all. I appreciate the info - still always learning on this, and you all have been invaluable.

I switched out the old AC 43’s with new AC 45’s. It sounds the best it ever has. But, now I’m facing a problem of overheating. I replaced my fan belt that same day - to a 1/2 inch smaller diameter, as the older one was stretched and slipping. My question is - would the AC 45’s result in a hotter engine, or would it more than likely be my fan belt causing the issue? Before I did these, I could drive all day in 90 degrees and the temp would stay below 120. Now in 80 degrees, 4 miles and it overheated.

Thanks.

The spark plugs would have no affect on engine temperature.

I thought not, but wanted to verify. Thanks.

Check the operation of the thermostat. While it is open flush the cooling system.

Sorry for the confusion. I think you meant that the new fan belt is 1/2” shorter in length.

I am trying to think why a new fan belt would cause overheating. Did you use the correct cross section belt?

Yes- I did mean it’s a 1/2 inch shorter. I believe it’s not the right belt, and is sitting too deep within the pulleys, and not spinning the pump / fan fast enough at idle. I found a resource who has the same truck and confirmed I am using a different belt width, as mine is only 1/2” wide, while he is running 11/16” wide. I am going to remedy that and see where it gets me.

If the belt is not the correct cross section (width & angle) it will not drive properly.