I want to replace the spark plugs on my 1963 F85, 215 4bbl, automatic. Manual calls for AC 45FF but I can't find those. They are out of stock. Anyone with a suggestion for a good replacement . Hard to cross reference these plugs.

 

You can use Champion RJ12YC, Autolite #275, NGK#BPR5HS

 

Can't tell you how many boxes of those I've seen at swap meets. Not that that does you any good, but that might be your best option to find genuine AC plugs.

 

I would go with the NGK you might be surprised in the performance.

 

Thanks for the info, Eric! It's very useful for me. I also was interested in replacing the plugs in my 63 Cutlass (215 cid ultra-high compression engine) and since I live in Europe, getting parts is not easy. Last time I was in the States a year ago, I stopped by a Napa and I believe I picked up a set of plugs for my car, but I can't tell which of these are for my 63 Cutlass:

AC/Delco R44T: BBC?
AC/Delco R45TS: SBC?
AC/Delco 41-630: I believe these are for my 88 Cutlass, 307 cid V8
Autolite AP 145: BBC?
Autolite 404: ???
Autolite 45: SBF, I believe

Yes, I have a bunch of cars, and now I have a big mess with my spare parts... LOL

Thanks for your help.

 

The 4 means 14mm threads
The 5 is the heat range
The FF means the plug has a 1/2" reach, fully threaded

The cross reference shows Bosch W9AC and NGK B5HS. Many others could be substituted if "close" is O.K.

The AC 45FF is not a resistor plug. If you want to switch to resistor, the numbers would be different.

 

I took a plug out of my 63 Cutlass today and it says NGK BR5HS. What's the difference?!

 

Adding the "R" makes it a resistor plug.
http://www.sparkplugs.com/Data/uploa...ug%20chart.jpg