1968 Corvette L-89 spark plugs
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3rd Gear
Joined: Nov 2007
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From: Kansas
1968 Corvette L-89 spark plugs
It looks like R43XL is the correct plug for the L-89 aluminum cylinder heads. I am looking for conformation of my findings. Can someone confirm this for me? Thank You.
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3rd Gear
Joined: Nov 2007
Posts: 3
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From: Kansas
Engine is fresh rebuild. It was broke in on dyno at machine shop. It had R43 plugs in it. I removed them for install into the car. Then I was talking with a guy (Mike) who said he thought it should have the XL plugs. I did some checking and that is what I found. Thanks for conformation.
We did lower the compression. Mike suggested running the R44XL. I got both from the parts store, R43XLS and R44XL (just to be sure they were the same). Would you recommend the R44XL as well? We are mostly concerned about the threads in the heads. The plug threads on the 43 are too short, most important that we get the correct length of the plug.
Thanks for responding to my question, Tim
We did lower the compression. Mike suggested running the R44XL. I got both from the parts store, R43XLS and R44XL (just to be sure they were the same). Would you recommend the R44XL as well? We are mostly concerned about the threads in the heads. The plug threads on the 43 are too short, most important that we get the correct length of the plug.
Thanks for responding to my question, Tim
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From: Bloomfield Township Michigan
Jeff
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3rd Gear
Joined: Nov 2007
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From: Kansas
"XL" plugs are the plugs recommended for aluminum heads The are 3/4" reach, fully threaded. A "43" is only a 3/8" reach which is way too short. If you are just looking for an AC plug that will run well, a 45XL or R45XL would be a good choice. As stated above, a 3 heat range is pretty cold. Just to be accurate- I have no idea if you are looking for originality for judging or a good running plug but the plug that came in your '68 L89 was a 43XL. R43XL was from 1969. Hope this helps.
Jeff
Jeff
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Joined: Jun 2001
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From: Thomson Georgia
that is getting it right
