spark plugs

[Ray G.]

Hello folks, tuning up my 427-400 hp 1969 Corvette coupe with new wires, etc and wondering what is your suggestion for spark plugs? I also have the K66 option Thanks,

[Joe L.]

Re: spark plugs

Hello folks, tuning up my 427-400 hp 1969 Corvette coupe with new wires, etc and wondering what is your suggestion for spark plugs? I also have the K66 option Thanks,

Ray------


Original plugs were AC R43N. These are still available from GM under GM #5613522. If I were going to use AC spark plugs, I might use the extended tip style R43XL (GM #5613312) or R44XL (GM #5612092). However, my preference is always for Champion spark plugs. If so, use Champion #123 or, better yet, Champion platinum #7405.

[Duke W.]

Re: spark plugs

OE plugs were too cold. AC heat range "5" is best for road engines, both big and small blocks.

There are lots of spark plug threads in the archives.

Duke

[Domenic T.]

Re: spark plugs

OE plugs were too cold. AC heat range "5" is best for road engines, both big and small blocks.

There are lots of spark plug threads in the archives.

Duke

Duke,
Yes today they are to cold BUT, they were not back in the 60's when the cars were driven like they were built to drive. Grandma used heat range 45, I used 42. Trucks that were driven hard also used low heat ranges. Today if you drive like we did you would be put in jail!!
I am a 43 heat range guy now. When drag racing the 42 range was preferred, street driving would foul the plugs if one didn't get on it. Today getting on it puts you in jail.

Dom

[Duke W.]

Re: spark plugs

Even back then you couldn't put high load/revs on the engine for very long unless you were road racing. When I started using AC 45s my 327/340, it quit fouling plugs. I used 43s for hot lapping Kent, and 45s were fine for drag racing because the engine is only fully loaded for a few seconds.

Duke

[Jim T.]

Re: spark plugs

Ray------


Original plugs were AC R43N. These are still available from GM under GM #5613522. If I were going to use AC spark plugs, I might use the extended tip style R43XL (GM #5613312) or R44XL (GM #5612092). However, my preference is always for Champion spark plugs. If so, use Champion #123 or, better yet, Champion platinum #7405.

Joe, Which one of the Champions are you going to use when you start your 1969?

[Joe L.]

Re: spark plugs

Joe, Which one of the Champions are you going to use when you start your 1969?

Jim-------


For aluminum head big blocks, my recommendation would be a little different. Here are exactly the plugs I'll be using:


DSCN3055.jpgDSCN3056.jpgDSCN3057.jpg

Champion #3405