I have a 350 out of a 71 camaro. the heads have been shaved down some due to warpage and I need to get the correct spark plugs for it. I am trying some AC r45ts and it will run but would like to know if they are the correct ones.

Thanks
George Jeffers

 

Run them for a bit then read 'em. That will tell you all you need to know.

 

After you run it a bit, look at the electrode. There will be a defined line that "should be" right in the elbow if the plug is the right temperature.

If the line is really close to the spark plug threads, the plug is too hot, go 1 step colder and see what happens.

If the line is past the electrodes elbow and closer to the tip, the plug is too cold, run a hotter plug and see what happens. The line will move when you go up or down in heat ranges.

AC Delco plugs go up in number the hotter the plug
42-cold
43-warm
44-warmer
45 hot

 

AC R-45TS is the stock plug for any chevy peanut plug head for normal driving and low compression.
For "performance driving" with higher compression you can try the plug for a Hi perf Z-28 or Corvette of the era.
AC R-42T or Champion RV8c. It's a non projected tip style that is a little cooler than stock. Works well for me.