Hi guys.

Already searched but did not find the answer I was looking for.

I have a 1984 L98 block with 1987 14101083 heads.

From searching I found out that these heads are 64cc chamber, flat top pistons with valve reliefs and 9:5:1 compression.

What would be the best way to get the compression higher? Want to go 10:x:1

Sorry if the question sounds stupid, always learning.

Thanks, Peter.

 

First you need to detremine piston to valve clearence, does your engine have a valvetrain? If it does place some clay on the piston tops, set the head down w/ out a gasket, snug up a couple bolts, set up the rockers on that cylinder, then turn over the engine by hand. Remove the clay & measure the thinnest part. You can get headgaskets in various thicknesses. Plus you can have your heads milled.
The ideal measurement is 0.040, this is called quench. Most engines when totally stock, the piston is down in the hole about 0.025.

 

http://www.csgnetwork.com/compcalc.html

according to that, using standard .043 over the shelf gaskets and an assumed piston volume of 5cc for the valve relief and a clearance of .025" in the hole (stadard sbc) you should be at 9.6:1. you can switch to a head with a smaller cc or run a thiner gasket.

the other options you have are mill the heads or the block.

 

GMPP head gaskets are .028. These will work if you have the room. I used these or my 89 L98.

 

Thanks.

Guess I'll give it a try.

1985 L98 motor with 1988 L98 heads. Should have the room for it. Right?

Peter.

 

should. might wanna check for valve clearance using the clay method anyway. should bump compression to about 9.96:1, almost to the 10:1 mark.

 

Is this an '84 with a '86, or later L98 TPI?
The Camaro Tech data shows;
"...It's rumored that records also show that 50 1986 350 (5.7) IROC's were built. These cars were built primarily for testing and were the ones we saw tested by the automotive press late in 1986...", or is this data incorrect?
The heads are definitely '87 L98s.
Thinner gasket as Travis said.

Milling the heads. I spec'd mine for 10.5 on 87 octane, with aluminum heads, otherwise I'd be running 93 octane with iron heads because it's a daily driver. Other than the weight difference my choice for alum over iron has more to do with creating hot spots which cause detonation especially in stop & go traffic, other than that for me there's not much of an advantage.
Remember this just my opinion, and experience.

Raul.

 

not a single one of these rumored cars has been found yet.

 

58cc heads and a .035 head gasket. Will bring you up to 10.5:1.

You will most likely have to measure for new pushrods.

 

if you go 58cc, you might as well go 58cc vortec heads and have some decent flow and make a lil more power in the lower rpms. but youll have to change to a vortec style intake though.

 

Decking the block for heights between the stock .025 and close to zero can be done, raising compression and increasing quench efficiency. Smaller combustion chambers with .025 deck height is not the best move if you're thinking pump gas, but it's the fastest way. The quench action would be less efficient. Another method for increasing compression can be done with your crank. Have your machinist offset grind it to 3.5" stroke. This will cause your pistons to come closer to the deck at TDC, just like decking the block. If you need your crank turned anyway, it's like decking the block for free! But your deck better be flat.

 

my guess is the OP isnt comfortable tearing into the bottom end. (correct me if im wrong) so the head swap/mill with thinner gasket would be the best bet for him to bump the compression.

 

Didn't get the bottom end thing, sorry. I have 305 Vortecs on my tow vehicle, they make me smile. If you don't want to change intake styles, try the 601s (some 305 HO and 267s from the '80s) with 1.94 intake valves, they have a nice chamber design that will help offset the quench issue.