AC Delco R44 spark plugs vs R43

[njsteve]

I wanted to try to find a set of AC Delco R44 plugs as that is the factory plug application for my 1969 350/300 engine. I noticed that the application has been superceded to R43. Correct me if I wrong but isn't that one heat range colder? Should I go ahead with the R43 plugs or hunt down a set of old R44 plugs. It's the original engine, now .030 over, with same compression 10.25 to 1 and the cam from a 350/350hp engine. The engine has 1100 miles on it and runs great with the Autolite plugs. No pings, no rattles on 93 octane premium. (I am putting the AC Plugs in for originality/show purposes) Thanks, NJSteve

[Norm reynolds]

Steve I thing that you will be fine with R43 plugs you will not know the diference I would ues them and just keep my eye out for the r 44s

[moparts]

[ QUOTE ]
(I am putting the AC Plugs in for originality/show purposes)

[/ QUOTE ]

Well at least now I know what the AC plugs are good for!
As Rob can tell you after a few hours on a dyno hunting for a few more horses, we found that about any other plug is better than the ac plugs.

[Salvatore]

R44's are 1 step hotter. They are a little easier on themselves because you usually lug the cars around at shows. Solid lifter motors are more prone to plug fouling I feel. I use Autolite in my 1969 Z/28. Use the 43's and 44's at shows. No big deal. JMO Sam

[njsteve]

I love Autolites. I put them in all my engines. They are just about the only thing my 426 hemi will take. It hates everything else, especially Champions, but loves the "Ford" plugs! Someone should design a slip on "AC R44" cover for the Autolite plugs, so they will look (and run) correctly at shows!

[Schonyenko2]

Sam, try a set of NGKs sometime. We are pretty fond of them. Schonye