tshirttom

While some engines like the spark plug's gap open to the intake valve, there are still other combinations that make more power with the gap pointed toward the exhaust valve. Has anyone experimented with this on the base 5.7L ? Details would be appreciated.

sperkins

Without a dyno, there's no way know if indexing is actually working for your particular engine. You could spend hundreds of dollars in dyno rental for 4-5 hp max.

tshirttom

Agreed. That's why I was wondering if someone had allready done this with a stock L98

sperkins

Maybe 2hp gain if you're lucky.
It would be easier to just clean or replace your air filter.

mr.beachcomber

While replacing the head gaskets on my both my L98's, I noticed that the stock 113 aluminum heads basically indexed the spark plug such that the open gap was towards the intake valve when torqued in place. Chevrolet may have already done the work for you to take advantage of the natural swirl in the SBC head.

BTW, I use anti-seize on the spark plug threads and use a steel spark plug chaser to clean the threads on each hole anytime I remove/replace a spark plug.