70 LS5 spark plugs.........

[Chris H.]

I pulled out the AC R43Ts and want to replace them with AC R45XLSs. The 45s are approximately a half longer than the 43s. I was wondering if there is a possiblity that the top of the piston will hit the plug.

The motor is stock and has never been apart. It's 10.25:1 CR.

Thanks, Chris

[Clem Z.]

Re: 70 LS5 spark plugs.........

no problem as there is plenty of room,but i do not think there is a 1/2" difference,only about 3/16". i have run XLS in 12.5:1 engines.

[Dave S.]

Re: 70 LS5 spark plugs.........

Chris, What is the attraction to XLS plugs? Why not run a R45TS? Its a nice hot extended tip plug.

[Clem Z.]

PS WARNING

i am used to working with BB heads that use the 3/4" reach plugs and GM did change to TS but i thought it was later than 1970.

[Dave S.]

Re: PS WARNING

I used R45TS AC spark plugs in my 70 LS5 and it ran quite well. Although some do not agree, I am a believer in using AC plugs from the 70's with the 4 green rings.