I’m sure this is all over the place here somewhere just not sure where to find it. Looking for plugs for 1970 LT-1. Same story, looking for what the manual says but auto parts doesn’t carry the AC R43, instead they have the R43s. Motor is new and so is the car to me. Is the R43s to long for the LT-1? Any suggestions for a different plug for normal driving.

 

You may want to go up in the heat range on the plug to a R-45 plug or equivalent. Hopefully, someone will chime in with a replacement brand plug. Jerry

 

The favorite plug around here is NGK...

 

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I used to buy the expensive aftermarket spark plugs and use them because of my high compression bb engine. They were pretty and worked well but it got expensive when you had to buy eight of them for my engine.
Using a MSD Ignition system I also used a larger gap in my spark plugs to ensure they would fire under high compression. I was wrong.

After a short discussion with one of our "Resident Experts" I soon learned that I was doing things the wrong way. It seems that for the best most reliable firing of the spark plugs in a high compression environment was the basic spark plugs recommended for this engine I have. The cheap AC Delco spark plugs work just fine so I chose to use the #4 "Rapid-fire" Spark Plug by AC Delco. It is a basic plug with multiple ground paths on the electrode. They are inexpensive and they work great.

On the 1968 427 it is possible to reach all eight spark plugs from above so changing them is not that hard to do. It is a 20 minute job when they are cool. If they were harder to change I might go with a more expensive type spark plug to get more longevity so I didn't have to struggle changing them as often.

Keep it simple and use the less expensive spark plugs. Stick with AC Delco plugs and they will work just fine with a standard ignition system.

Just how much technology can they put into a spark plug after all?

 

R43 plugs are too cold for normal driving, unless you're planning some track use.

I have been using NGK B4 plugs for many years without any issues. (These are non-resistor plugs)

 

There is nothing wrong using a R43S plug if you can find it, a little cold. Next would be a R44S again if you can find it. You can cross reference to other manufacturers.