Austinbelair

iTrader: (2)

Can anyone help me out with how much to shave LS3 (821) heads on a flat top 370ci 6.0L? Cam is Cam Motion 220/234 114 .610"/.615" with LS9 head gaskets, an LS3 intake and not sure on springs yet.

Before I knew any better I had told the shop to cut them .005" to clean em up. Well, they did it and now I realized I probably should have gone deeper? They charged $150 for the first shave and it will be another $150 if I want to cut them more.

Street 87 C10 short bed. Occasional daily drive and weekend toy really.

Cam Motion told me .030 would put me at 11:1 and if I go .020 that would put it at 10.9:1 but at the .005 I am at now I'd venture a guess that I am only at around 10.6 or 10.7:1

Is this going to be decent on pump gas for what I want?

AINT SKEERED

iTrader: (2)

Why not just use .040 gaskets ? Better than milling more

Austinbelair

iTrader: (2)

I honestly don't know why I didnt think of that. Is there a GM MLS gasket in that thickness? I kept reading how amazing the LS9 were so I went that direction.

AINT SKEERED

iTrader: (2)

felpro and cometic are your choices but still cheaper than shaving heads and the tighter quench are better for less chance of detonation

01CamaroSSTx

iTrader: (3)

Run 93 octane and you'll be just fine!

01CamaroSSTx

iTrader: (3)

A 4.030 bore with 3.622 stroke and 68cc heads, flat tops and assuming a zero deck with a .051 head gasket yields 10.6:1 with dynamic compression roughly 9.5:1 so you will be just fine on pump gas.

5.7stroker

iTrader: (36)

Measure how much the pistons are in or out of the hole before buying the gaskets if you want to dial it in. If you are just wanting to know if it will be good on pump gas then like 01CamaroSSTx said, you'll be fine. Here you go:

https://drive.google.com/file/d/1MDT...CcBIIrpiv/view

Austinbelair

iTrader: (2)

For curiosity sake I looked up the Cometic and all I see for LS is 4.000" and 4.060 bore. If i'm at 4.030 do I just use the bigger 4.060?

G Atsma

Yes. You never want to use smaller than the actual bore.

00pooterSS

iTrader: (40)

These would work good. .045 thick, for use up to 4.070 which will work for your 4.030 bore and 4.065 heads. They also give you a little better quench coming in at approx .039 vs .046 with stock gaskets.
http://www.ws6project.com/user_stor/...oducts_id=6485

They are $70 too and MLS

I'm not sure what CC you're at with .005 shaved off but I used 68 cc in the calculator and got 10.94 with the above gaskets. At 69 cc you'd be at 10.81

With stock .052 gaskets (run LS3 gaskets) you'd be at 10.63 with 69 cc heads and with 68 cc you'd be at 10.75

Any of those ratios is pretty good. I personally would like to have around 11:1 to 11.5:1


All ratios are with using .006 piston out of the hole.

5.7stroker

iTrader: (36)

Check out cell B10 in my calculator. It lets you enter amount shaved off the head.

00pooterSS

iTrader: (40)

Where is your calculator?

5.7stroker

iTrader: (36)

It's in the link in post #7 of this thread.

00pooterSS

iTrader: (40)

I punched in a few numbers and one of the things I noticed is the quench calc is backwards or the piston in the hole. You put on there a negative number means piston in the hole, that should be out of the hole

I put in a .052 gasket with piston coming out .007 and it's telling me that's .059 quench. It should say .045

5.7stroker

iTrader: (36)

The formula for quench is compressed gasket thickness minus piston out of the hole.

If you change the piston compression distance such that it shows "+0.007" in row 12 that means it's coming out of the hole 0.007. If that's what it shows in the cell and you are using a 0.052 gasket it should calculate the quench as being 0.045.

https://ls1tech.com/forums/generatio...te-quench.html

00pooterSS

iTrader: (40)

Yes thank you I understood how to calculate quench when I understood second grade math. I don't know how tall you are but my post went far over your head.

Try re reading it.

Your tool auto populates piston out of the hole. Then it auto populates quench. And it is populating wrong.

YOUR TOOL NEEDS TO BE CORRECTED. I DON"T NEED SCHOOLING.

Read the part in red a couple of times.

5.7stroker

iTrader: (36)

My bad I was trying to look at it on my phone. Thanks again for finding this error. I made some corrections. New link here:

https://drive.google.com/file/d/1gmUWLXWxISqxcCgfYaVuZSWShXtJs4I-/view

JimMueller

iTrader: (9)

I think you still have a typo in your quench formula. Quench should be the distance between the top of the compressed gasket and the top of the piston at TDC. You have cell B15 (piston deck clearance [positive is below the deck]) at 0.007, and cell B5 (compressed gasket thickness) at 0.052 and cell B21 Quench at 0.045. The quench should be 0.052+0.007=0.059; if the piston was -0.007 (above the deck) then the quench is 0.052+(-0.007)=0.045.

JimMueller

iTrader: (9)

How did you calculate DCR without knowing advertised IVC?

Darth_V8r

iTrader: (4)

Add 27 degrees to your 050 IVC. That will get you close enough. Or add 54 degrees to your 050 duration.