I would do a cam swap over anything else mentioned in this thread and a 93 octane hot tune....


As for some of the other responses in this thread....

My heads are milled .030 and I use a .040 head gasket... So I removed about .044 from the heads to the block measurement... I run a pretty high lift cam and i shift at 7k regularly, with no issues...

Personally i would shoot for 10.8-10.9 cr, nothing really over that... You just got to have goood exhaust (headers, etc...) and some good flowing heads to run the higher CR...

 

so adding stock 243 heads and stock gm gaskets to an lq4 shortblock will generate a 10.5:1 cr?

factory lq4 is 9.4:1 with a 72cc head (6.5-6.7cc dish in the piston)
243 heads are 65.6-66cc stock

putting a 66cc head on a 9.4:1 motor will not get you 10.5:1 compression assuming use of the same head gasket.

to the OP:

i'd mill 10thou off the heads just to clean them up and use a .041 gasket. compression is your friend. your only battle will be with octane. don't overdo the cr if you don't have the fuel to support it. you'll make more torque, lower in the band with higher compression. not to mention, assuming the proper tune, higher compression simply means a more efficient motor, period.

and valve lift hardly has anything to do with piston to valve clearance. the valve events in general, moreso the duration and lsa, play the biggest roles in ptv. your factory lq4 pistons have a HUGE dish in them. even milling the heads and running a thinner gasket...you'll still have gobs of room should you choose to run a monster cam down the road.

edit: as always, mock up your **** and take pre-mill measurements. crunch numbers on gasket thickness, final compression ratio, and fuel available.

 

You're looking at around 10:1. A little higher if you mill the heads. IMO that's a perfect street or d/d ratio cuz you can run some 89 ethanol in a pinch. Or you could even tune for 87. And if you get a bigger cam your engine won't be so fussy, like pinging and stuff that I was struggling with.

Just get some 8.1 truck injectors and a good tune, you'll be all set. Definitely do your research when choosing a cam