i always see on tech where they use thinner head gaskets to up the compression a bit. i dont see it done often here....how big of a difference in power would i see from the small increase in compression, and is it worth the money. how much round-about would i spend total for everything to be done right. the engine will be on a stand so if im guna do it i figure now is the time to go for it.

i know if i did this i would need to get a pushrod checker to get the right length pushrod, but would i have to do anything to the head to make it seal back down to the new gasket, or could i just yank it off, put in the new gasket and slap it back in and torque it to spec

 

Stock head gaskets are .054 thick. I was going to use .045 thick Cometics on my head swap, mostly to decrease the quench area for better combustion. It was also going to raise my compression .15 of a point. But I ran into problems and was crunched for time so I used stock gaskets instead.

If you have plans to pull the heads for head work then it is worth going with thinner gaskets. But there is no way I'd pull heads for the minimal gains from just changing head gaskets.

My 3.910 bore .045 thickness cometics cost about $140. Now they sit on a shelf in my basement. They are reuseable. The instructions say to install them dry, but a lot of guys on tech use the copper gasket spray to help them seal better. I should have followed their advice and used the spray because I had a tiny coolant weep on the passenger side, probably due to my block prep (Cometics are finicky, the surface has to be perfect). I didn't have the time to let them air dry 24hrs and use the spray, so I used the more forgiving stock gaskets I had.

 

its also a 100k old motor so i kinda want to see whats goin on in there.

 

Then use a borescope!!!




PS:
FelPro 1041's are used quite a bit. .041 compressed thickness. If you do this then yes you will want to look into rod length. They will end up being too long.. The gain you will get with that thinner gasket will be negligible at best. Furthermore, not worth the money or hassle!

 

Have you run a leakdown test on it yet Stewart? Pull the pan and inspect the pistonsf rom the bottom for excess skirt wear, hot main, hot rods etc.

 

You need to check that the head gaskets leave you enough piston to head clearance,because with stock pistons your deck height is out of the block.I wouldn't go any thinner than .045" thick head gaskets,milling the heads might be a better way of raising your compression.Spring for a valve job while you have the heads off.

 

You can check your pushrod length here. Just remember to reset the gasket thickness and milling to stock on this calculator. Give it hell!
http://ourworld.cs.com/ls1info2/Pushrod+calculator.xls

 

I'm running 243 heads (64cc) and have cometics .040" head gasket. I really wanted the .045" to help keep the CR & DCR down a bit but TSP sent me the wrong ones and I was too impatient to send them back. The thinner head gasket also helps against detonation which is good since I'm running about 11.3-11.5 CR.
Use the copper spray, although they say its not needed its cheap insurance against leaking coolant. Its been awhile since putting this engine in and no leaks so far.
I'm also using 7.4" pushrods and its pretty quiet.

 

as a mod- hell no.
if you have your heads off already, compression is awesome.

 

how about i bring it to you and let you show me how to do all this leakdown, compression and piston skirt crap...while im there you can show me how to swap a motor too