Mikko

My unopened LS3 with Paxton novi 2200 started to overheat and makes pressure to cooling system after harder pull. Coolant coming out of reservoir and lots of air in radiator. So somesord of failure.

Iīve been running with 7-8psi, e85 with safe tune. 730fwhp/870nm. Recently swapped from 6-rib to 8-rib belt and pulleys and boost had raised few psi and didnīt notice it right away.

What is most typical issue in these? And known fixes. Didnīt find much with search but there is little language barrier, iīm Finnish.

I remember hearing something about heads lifting or backing up but now canīt seem to find anything about it... Any info on this?

Fix?
Some better gaskets. Cometic MLS, LS9 ones? Straighten heads if needed.

And ARP bolts or studs?
http://www.summitracing.com/dom/part...make/chevrolet
http://www.summitracing.com/dom/part...make/chevrolet

or
http://www.summitracing.com/dom/part...make/chevrolet

These all fit right? Can i mount studs without any engine work? meaning those doesnīt effect on bore? (Disortion etc)

Anything else? Or any other wise modifications to do at same time? lifters? pushrods? Cam chain? Itīs been driven now maybe about 200 race hours.

Engine is completely stock besides lunati cam, lunati valve springs and retainers. arp conrod bolts and acl rod bearings.

conan

iTrader: (5)

LS9 gaskets with ARP studs for sure. Might want to do the lifters / trays while the heads are off. I would take the heads to a machine shop and have the decks checked and milled if needed. You could do the trunion upgrade to the rockers arms at this time too...
http://www.texas-speed.com/p-361-com...s-engines.aspx

Mikko

Why ls9 gaskets over cometic mls ones? Asking cause i can get cometics from my sponsor but not gm parts. Sure if Ls9 ones better...

so not any issues with heads failing?

conan

iTrader: (5)

GM gaskets are cheaper to us than Cometics and work just as well. GM MLS are a little more forgiving than Cometics when it comes to the block deck and heads being perfect. I've ran both Cometics and LS9's and have had no problems with either one. I would recommend some copper spray for what ever gasket you go with.
https://www.google.com/shopping/prod...ed=0CB8Q8wIwAA

Blown06

iTrader: (32)

I like the cometics. If you can get them from your sponsor, no question that is what you should do.

Bob@BruteSpeed

iTrader: (16)

If you go with Cometic head gaskets, below is what Cometic recommends:

What surface finish is required to us an MLS head gasket?

A surface finish of 50 RA (roughness average) or finer, is recommended for a proper gasket seal. Anything rougher may conflict with the gasket design.

What head bolt/stud torque do you recommend when using an MLS gasket?

When using MLS head gaskets always refer to the manufacturer of the fastener to determine accurate torque values. Appropriate torque is critical when installing new gaskets of any kind.

Why does Cometic recommend MLS gaskets to be installed dry?

Cometic Multi-Layer Steel (MLS) head gaskets go on dry because they are coated with a sealant. Each MLS head gasket is coated with a .001" thick Viton rubber that is bonded to the outer stainless steel layers. Adding an additional sealer can hinder the performance of an MLS head gasket.

http://www.cometic.com/technical.aspx Bob

Mikko

Pulled engine out and took it open

No any significant sign on gasket failure and heads seemed to be straight, few headbolts were pretty tight to screw open. Meaning all loosened ok but some were pretty tight to screw open...?

But couple other things
E85 has done something to cylinder walls...? Maybe leak sign in there also?


And this... Stock pistons, still unopened engine. Valve springs...?


So, suggestions for connection rods and pistons, and length for rod?

Think that iīm going to keep stockish compression ratio still.