Double Check This For Me
Thread Starter
TECH Apprentice
Joined: Mar 2011
Posts: 324
Likes: 25
From: Waterford, MI
Double Check This For Me So I think I have everything covered, but double checking here. I bought a 98 Z that has a built LS1, but spun a bearing. My plan is to swap everything over to a LQ4 short block. Since the LQ4 has a lower compression, my plan was to use a thinner head gasket (.041). I'm still trying to verify which head gaskets were previously on there, as far as thickness goes. Previous owner had receipts for everything, but those came in a kit. Aside from checking push rod length (do I even need to do that for a thinner head gasket?), I don't think I need to worry about anything else do I? Swap the cam, heads, etc all over and good to go. I shouldn't need to worry about piston to valve clearance since this is a dished piston, compared to the flat top on the LS1.
a .041 will be about .010 thinner than the stock gaskets and will make the valves .010 closer to the pistons, but what cam are you going to be running?
If you need more compression the best thing to do is get a set of 243/799 heads.
If you need more compression the best thing to do is get a set of 243/799 heads.
Thread Starter
TECH Apprentice
Joined: Mar 2011
Posts: 324
Likes: 25
From: Waterford, MI
The cam is 234/238 - .612/.612 - 112+4. A custom grind from Futral. I want to keep the heads I have since they have pretty good amount of work already done to them. CNC machined, bigger valves, etc. It seems it will only go down from 10.5:1 to 10:1 by using these heads. Maybe don't worry about the lil dip in compression? Thinking about it, I'll probably make up for it with more cubic inches.
Just realized, I forgot to mention, the head from the LS1 are 243s already. That's what will be going on the LQ4
Just realized, I forgot to mention, the head from the LS1 are 243s already. That's what will be going on the LQ4
In 1998 they would have been 806 with perimeter bolt covers. But he stated the car had a built ls1 so they may have been swapped already.
Last edited by LLLosingit; Sep 11, 2019 at 02:06 PM.
LS1Tech Sponsor
Joined: Jan 2008
Posts: 2,233
Likes: 1,523
From: Ohio, Georgia, Nevada, Texas
The iron blocks vary in deck height, so it's best to verify how much positive deck with a bridge indicator. Spec was about .006 positive with a .051 gasket so a net of .045 piston to head. Going .040 gasket would make the piston to head .034 in., which is about .002 shy of where it should be. If your block is lower (as many are), it could really be pushing it. For that reason, a .045 gasket would be a bit safer if you find anything more than .006 positive deck. Check out this one that also limits bore diameter to 4.060.
Trending Topics
Thread Starter
TECH Apprentice
Joined: Mar 2011
Posts: 324
Likes: 25
From: Waterford, MI
Not positive if the heads have been previously milled, the receipt from the machine shop did not indicate that.
Heads are currently at 65.5cc
Yes the heads were previously swapped from 806 to 243, along with an LS6 intake and a bunch of other stuff.
Maybe I'll play it safe and stay with a .051 head gasket. I don't plan to have any additional machine work done. I was going to drop everything on to the LQ4 as is since it's low mileage,looks in good shape and the LS1 was built up only about 10k miles ago.
Heads are currently at 65.5cc
Yes the heads were previously swapped from 806 to 243, along with an LS6 intake and a bunch of other stuff.
Maybe I'll play it safe and stay with a .051 head gasket. I don't plan to have any additional machine work done. I was going to drop everything on to the LQ4 as is since it's low mileage,looks in good shape and the LS1 was built up only about 10k miles ago.
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Compression is free power and that cam will appreciate it. Your buying headgaskets anyway, why not make the most of it? But if you don’t have the means to properly measure where everything is, like Summit mentioned, you prolly should just stay safe for now. You can always tear back into it later and shoot for more.