[1971455HO]

Thought I would just post this from my Sun Tune cards.

Just in case you're one of the few on here that does own a 1969 RA IV and wanted to know exactly what your stock tune was back in the day. I'm pretty sure the 1970 is the same specs. Lot of info on these cards.

Lucky you, if you have one, I know you're spending bigger bucks than most of us for the good stuff (gas).

[Formulabruce]

NOTE guys, the 43 and 44 plugs .. NOT 45's...... That are too darn HOT!!
Lots of info here, thanks for posting !

[unruhjonny]

yup;
I think the R45S is only good for 1970 engines with #13 heads, and 1969 engines with #62 heads.
Those R44S plugs are getting tougher and tougher to find...

[Formulajones]

R44S seems to be a non stock item. I can get the R43S all day long however.

AC has been eliminating certain heat ranges in various applications the last few years.

[unruhjonny]

I believe AC Delco discontinued the R44S around the time I bought my car - mid 1990's - if not earlier than that.
I believe I have two sets, but you have to really play your cards right to get them at a good price.

I have some other 44 heat range plugs which I believe should work - but would be noisey.

either 44S or R44... can't recall which.

[Formulajones]

I switched most of our cars over to Autolites when AC started playing that monkey business.

[Sirrotica]

I for the life of me don't have any idea why anyone would want AC plugs anyway, I worked in the 5 major GM brands as a line mechanic, and hated using AC plugs. On brand new AC plugs I've actually had the ceramic insulator blow out upon startup. In my fathers 63 Bonneville he used to foul the Factory speced AC plugs in it constantly. Switched to Champions and never fouled another plug for years after that.

I guess everyone has their reasons, and I have mine, and have taken tons of BS for using Champions. However like everything you're not getting the same quality parts that you were 25-30 years ago either, no matter whose name is on the box.

The reason I started using Champions over 50 years ago, Milt Schornack and Royal Pontiac used them in all of their cars in the 60s-70s. If ACs were so good, why did Royal use Champions?

Let the feathers fly...……...

[unruhjonny]

I find it funny that Autolites were mentioned;
I was recently scoffed at for using them, and I reasoned that when I started using them the quality was apparently up from where it was;
I liked that I could get precise heat ranges with no monkey business...

Long story short, my former '73 Formula was having running issues, and the autolights I bought for it were cited as the first problem... forget that at the end (I wasn't there) it looked to be was a faulty condensor on the coil!(!!?)

[Formulajones]

Scoffed at? LOL That usually comes from people that don't have a real understanding. Sometimes brand loyal people can't see the forest for the trees.

They work and work very well. They carry all the heat ranges that AC has dropped, and then some. Especially when you get into the 3/4" reach plugs for aftermarket aluminum heads.

I also use NGK, but you have to be aware that the heat ranges work backwards from our conventional thinking, and they make some pretty cold plugs. If you need hotter plugs the NGK's only go so far.

[unruhjonny]

/\ ha!!
I have dabbled with NGK's too!!

this recent scoffer was telling me that he has observed that Autolites foul quickly;
Now, he ABSOLUTLEY has been a brand loyal person, so that is probably a factor... or is it?

I appreciate your opinion - as they say the proof is in the pudding, and the E/T's you have pulled in your Formula are all the proof I need

[Transamric]

I'll chime in with a big thumbs up for either NGK or Denso (formerly Nippondenso) as being of high quality.
But if you need AC's for appearance purposes, I used either R43 or R43S. But this was back in the day when we could still buy Chevron 104 white pump!!

[Norwood]

Ive been using Autolites for years with no issues