Boring or bigger sleeve??

[ABW]

What is the biggest you can make a 4.2. Can you stroke a 4.2?

[ca434sbc4]

Bore wise - the diameter is restricted by available head gaskets. Make the bore bigger - the gasket hangs in the bore.

Stroke - its already under square and rod/bore clearance is tight.

Better to work on the airflow - via porting and cams if you don't want to go forced induction.

[CNC-Dude]

Getting a copper head gasket made or even a good quality composition one in a custom bore size is not that expensive, especially if you're boosting the engine and need something a little bit better quality than what's already available.

[ca434sbc4]

The stock head gasket is a multilayer steel type much like a cometic. GM did there homework on it...

[CNC-Dude]

I meant MLS, not composition. I"m used to the pre-historic older inlines and am trying to ween myself away from them and those associated with them and join the 21st century.LOL