91yj

I have a set of ported 806 heads that I put on my 6.0 lq4, I used GM mls gaskets and its leaking coolant. I had these same heads on my 5.3 with felpro mls gaskets with no problems. I didn't realize there was a difference between "cometic" mls gaskets and GM mls gaskets, I'm also not even sure if these felpro gaskets are cometic? They don't have the rubber lines around them like the GM gaskets do, and as far as I can tell that is the only difference between cometic mls and GM mls????

Does anyone have an explanation how these felpro gaskets could seal with the notched head casting while the gm mls leak?

edit: the gaskets I'm looking at getting are Fel-Pro 26192PT, heres a link to them on O'reillys website

http://www.oreillyauto.com/site/c/de...eyword=26192pt

03Sssnake

iTrader: (20)

The GM MLS gaskets do not work with the notched 806 & 853 heads, graphite gaskets for sure and I have heard cometics with copper spray on both sides work as well. That being said, you could have them milled down to remove the notch so they will seal with MLS, imagine it would take close to .030 to remove the notch.

91yj

I've tried the graphite gaskets, but they weren't made for a 4.0" bore as far as I know. The ones that were supposed to have a 4" bore were stamped 5.7L and had a 3.965" bore.

Does anyone know if these fel-pro gaskets I listed above are cometic?

03Sssnake

iTrader: (20)

I gotcha bud, totally missed that...I was tired. Those are MLS and composite.

https://ls1tech.com/forums/16571130-post5.html

91yj

No problem man, thanks for the help. There doesn't seem to be alot of info on these gaskets. I ordered them from Oreilly and I'm gonna pick them up today, hopefully I can have them installed this weekend. I guess I was using the wrong terminology, Cometic is a brand of gasket correct? If these gaskets are mls AND composite does that mean they have sealant covering the outer mating surfaces? It also looks like they have raised edges where the coolant jackets are in the heads and block?

3rdCoastPowerSports

iTrader: (5)

take the heads to a machine shop, have them weld the "wedge" then have them mill the heads. Now you can run any MLS gasket you want. Done deal.

trjk07

I ran mls on 806 heads on my 6.0 and got lucky. I am taking these 806 ported heads with 2.02 valves to be milled .030 . Any info on pushrods mods? Or does the lifter compensate for the milling?sorry forgot to say I'm putting them on a 04 5.3