1971 LS-6 spark plugs

[Joe L.]

Re: LS-6 plug mystery

Warren-----

By the way, both the R44XL, aka GM #5612092, and the R44XLS, aka GM #5613870, are still available from GM and Delco dealers. I would recommend using the XLS-style, extended tip plugs, though. Of course, I'm not a big fan of AC spark plugs. Personally, I'd use the Champion-equivalent plug RN14YC.

[Chas Kingston]

[Chas Kingston]

[Joe L.]

Re: 1971 LS-6 spark plugs

Geezer-----

Yes, the "over-the-counter" LS-6 was the Chevelle version of the LS-6 and not the Corvette version. Basically, the only difference between the Chevelle version and the Corvette version was that the Chevelle version used the cast iron heads and the Corvette version used the aluminum heads.

Originally, there were complete SERVICE engine assemblies available for both the Chevelle and Corvette versions of the LS-6. Both of these were discontinued years ago. The last available "LS-6" SERVICE engine assembly, GM #366250 and the engine assembly that I'm sure you're referring to, actually was a "hybrid" that differed from either the Corvette or the Chevelle engines. For the most part, it was similar to the original Chevelle LS-6 of 1970 and the stillborn Chevelle LS-6 for 1971. Among other parts, it included the Chevelle oil pan and Chevelle long-leg style waterpump. However, it used 10.2:1 compression (1970 Chevelle LS-6 was 11:1 and the stillborn 1971 Chevelle LS-6 would have been 9:1) and it used the GM #3933163 high rise aluminum manifold. The 1970 Chevelle LS-6, the 1971 Chevelle LS-6 (if it had been produced), and the 1971 Corvette LS-6 all used the low rise GM casting #3963569 manifold. No PRODUCTION LS-6 was ever fitted with the high rise GM #3933163 intake manifold.

[Joe L.]

Re: 1971 LS-6 spark plugs

Geezer-----

Yes, the "over-the-counter" LS-6 was the Chevelle version of the LS-6 and not the Corvette version. Basically, the only difference between the Chevelle version and the Corvette version was that the Chevelle version used the cast iron heads and the Corvette version used the aluminum heads.

Originally, there were complete SERVICE engine assemblies available for both the Chevelle and Corvette versions of the LS-6. Both of these were discontinued years ago. The last available "LS-6" SERVICE engine assembly, GM #366250 and the engine assembly that I'm sure you're referring to, actually was a "hybrid" that differed from either the Corvette or the Chevelle engines. For the most part, it was similar to the original Chevelle LS-6 of 1970 and the stillborn Chevelle LS-6 for 1971. Among other parts, it included the Chevelle oil pan and Chevelle long-leg style waterpump. However, it used 10.2:1 compression (1970 Chevelle LS-6 was 11:1 and the stillborn 1971 Chevelle LS-6 would have been 9:1) and it used the GM #3933163 high rise aluminum manifold. The 1970 Chevelle LS-6, the 1971 Chevelle LS-6 (if it had been produced), and the 1971 Corvette LS-6 all used the low rise GM casting #3963569 manifold. No PRODUCTION LS-6 was ever fitted with the high rise GM #3933163 intake manifold.