OEM spark plugs

[Warren F.]

I am looking at some spark plugs on ebay. They are AC 443XLS, GM# 5613395.

Are these a correct application for a '71 LS6 application?

Thanks in advance for replies, Warren

[Mark #28455]

Re: OEM spark plugs

No. They will work but were not factory equipment on the LS6. They were the over the counter performance plug.

[Warren F.]

Thank you... Mark *NM*

[Duke W.]

Re: OEM spark plugs

"Performance plug" doesn't mean you want to run it in a street engine. "Performance plugs" are typically just like the OE plugs, but a colder heat
range, which makes them suitable for extended high output, such as racing.

For street driving you need a relatively "hot" plug because you spend very
little time at full load.

The OE plugs meant for "town and country" driving are a bit on the cold side,
and most Corvette engines operate better (less tendency to foul plugs)
by using one heat range hotter than OE.

Duke