killer01ws6

I am going to be doing unmilled PPRH 5.3 heads, running 2.055 and 1.60 vavles with a 228/228 588/588 112+2 cam package.


If I run the Cometic's will I have any issues?

They say you need less clamping force with these Gaskets,
Do you still do the same head install procedure ( same passes, same Tq specs)

Thank you for your responses up front.

Pete

strokedls1

iTrader: (1)

Well you can get different thickness gaskets from them so it depends on the thickness. I sprayed mine with some copper gasket spray and torqued it down. I went to higher than stock torque, but I have an iron block. Stock torque readings will work fine.

Steve - Race Eng

iTrader: (1)

Cometic gaskets work quite well if installed per instructions. The mating surfaces need to be as flat and as smooth as possible. Install the gaskets dry, no sealers, etc. Torque to spec.

These engines, regardless of gasket type, need to have the head fasteners retorqued for high performance use. I always recommend this be done after the first start, heat up cool down cycle. Back off each bolt, (nut if using studs) in the proper torque sequence and bring back up to spec. It wouldn't hurt to do this again after a month or so of running. Better safe than sorry.

John B

iTrader: (10)

I spoke with the Engineering Dept at Cometic when I bought mine and they told me that all head gaskets except theirs require a re-torque.

Boosted LS1

I thought the whole idea of torquing the bolts/studs was to put some tension into the bolts/studs and get some clamping done. So, this is done to locate the heads properly and I'm not sure why it would change because the gasket was changed to a different type. What are the specs of the Cometic gasket that make it different? I'm curious as I have heard they are quite good. Thanks.

slyws6

I'm having my 6.0L block machined for O-rings, how well will cometic gaskets work with the lockwire orings and anything special I need to do to them when installing them this way??

-Sly

John_D.

iTrader: (2)

Steve and John B, that would be bad advice for somebody with stock head bolts wouldn't it? They'd have to replace the bolts to retorque the heads? Or are you saying you only have to retorque when you use studs?

(I'm studded and o-ringed by the way... Stock head gaskets. So I'm interested in this topic. Engine is still on the stand for now.)

Steve - Race Eng

iTrader: (1)

My response regarding retorque was for aftermarket hardware not the stock TTY bolts. I don't use stock hardware in my engines as I'm sure is the case with most all shops.

Regarding o'rings with Cometic or any MLS gasket. They will not work with stainless o'rings. If you o'ring for an MLS gasket use copper wire only. I've seen this setup take over 35 lbs. of boost on a Honda engine.

If you have already installed stainless steel wire in your block or heads you will need to use a composition head gasket or copper if race only.

John_D.

iTrader: (2)

Good point about shop work vs. diy.

Just thought I would mention the stock bolts in case somebody read the comments about retorquing, and didn't think it all the way through (if they have stock bolts)....

Thanks for the tip on stainless vs. copper. I wasn't aware of that. I have stainless, so it's a good thing I used stock gaskets!

John B

iTrader: (10)

When I bolted up my MTI S2 heads to my LS1 block with GM OEM head gaskets and new OEM bolts I never re-torqued the head bolts and everything was fine. The service manual does not say to re-torque.

Shinobi'sZ

I have Cometic MLS Gaskets. I used Copper Coat because it was my understanding that LPE was doing this on their 427cid TT setups. I called Cometic and the Tech told me that I didn't have to do that. I haven't got any leaks yet..but am conscious of it. The Gaskets in MLS form from Cometic come with a type of sealant already on the outer layers...when they get hot apparently it helps them to seal. However, I have read and been told you dont have to re torque MLS style gaskets....I did anyway.

killer01ws6

I will be using ARP bolts,
but is sounds like I should install them per normal tq specs, then I should be good to go.

Thanks for the responses.

slyws6

Do the ARP studs come with torque specs does anyone know? If not what are the ARP studs torque sequence and specs? Thanks.

-Sly

killer01ws6

Can someone tell me What thickness I will need for the 5.3's unmilled?

Thanks,

Pete

strokedls1

iTrader: (1)

It depends on the pistons your using (whether they have valve reliefs), size of cam, and the comp ratio you want to get. .052 is stock compressed height.

killer01ws6

Sorry, I had most of that at the top of the post.

PPRH 5.3 heads, running 2.055 and 1.60 vavles with a 228/228 588/588 112+2 cam package, stock pistons with no valve reliefs.

I understand the 5.3 heads will give me about 10.8 I would like to be around there to 11.0

Thanks,

Pete

jrp

iTrader: (16)

im probably gonna run a felpro .043 gasket myself.

SAM98WS6

i used cometic .043. They told me dont put any sealer on them and no need to retorque. HOWEVER i did retorque after they sat an hour. required about four passes until the APR studs didnt turn at all. You cannot just do the torque sequence once and stop. GO BACK OVER THEM A COUPLE TIMES. Ive had no issues. If i would have been running boost I would do what Steve said and retorque after a heat cycle just to be safe.

strokedls1

iTrader: (1)

You could probably do an .045 and be ok on p/v and get a little more compression. Check out www.rosspistons.com for a calculator to find exact compreesion.

killer01ws6

ok,
Looks like the .045 would work for me.

Any more info from people that have done them would be cool.

Thanks,