I know the proper spark plug as recommended by the factory on a 69 400cu. in. is the AC R44S however the Resistor plugs are no longer available. Does anyone have a recommendation for a good set of replacements?

Thanks
Sena

 

I just put R45S in my '68 4-4-2 automatic, original 400 engine rebuilt 30 over, and it runs great!

Randy C.

 

+1. The R45S is what I ran in my 69 442 400 G
WHEN it was on the road. Ran great but they too
are getting harder to find. well, the acniter with
the green stripes anyway.

 

How do you feel about the NGK Iridium IX plugs (XR5IX)?

 

I run Autolite 85.

 

Probably a good plug, but way overkill for what is needed. And at over $10 each kinda on the expensive side.

 

You can still find the AC R44S plugs for sale. Just do a Google search. For example, here are 3 on EBay:

https://www.ebay.com/itm/15521431010...kB27HBn8d20%3D


Due to scalpers in the market, pay close attention to the price.

Although I run the R44S plugs, I am moving on the the newer technology offered by the NGK brand. The additional longevity provided by the NGK design should close the gap on the price differential.

Autolite is the only brand of plug, that I have personally experienced snapping off flush with a cylinder head. The bonus experience of removing the head to extract the base of the plug, led me to a lifetime ban of Autolite plugs.

 

I have purchased R44S green stripe on ebay before, I think it was $80 for the set of eight.

 

They pop up from time to time.
https://www.ebay.com/itm/14477710954...Bk9SR7jQ292QYQ

 

Then you have guys like this.https://www.ebay.com/itm/30469745685...Bk9SR7TQ292QYQ

 

There is a sticky in the tech editors section on spark plug cross reference.

 

I had that happen on a car I bought that the previous owner had installed Autolite plugs. Luckily I was able to get the threaded section out with a HUGE easy out. I have the same ban in place due to that experience.

 

I had the same tool, but it appeared that debris may fall into the cylinder. If you search the internet, you will find that we are not alone in our experience.