Mekkadon

iTrader: (3)

Hello all. I have a small problem. I have the TTi Race Kit on my car w/T76GTQ. 370ci iron block. -20cc dished Ross pistons. Heads are the stock LS1 castings, with a Stage III CNC port and polish. Heads were slightly milled to make for a even, flat surface with the block. Running 15#s of boost with 12-13 deg. timing on 93 octane. Running Cometic head gaskets @ stock thickness. ARP head studs. Compression ratio is 8.5:1. I have plenty of fuel (60# injectors, dual intank walboro 255's). AFR is at 11-11.5:1 on the street at WOT.

The problem is that coolant is shooting out of the small overflow canister under boost.

My questions are:

1) I am guessing that I should switch to a stock GM MLS head gasket?
2) What should the ARP head studs be torqued to?
3) If i do the above, and I still have the coolant problem, what else should I look for?

Thanks for any help in advance.

y2khawk

iTrader: (5)

how big is the overflow? There's a reason the stock one is as big as it is.

things to check:
bad gasket
poor gasket seal
cracked head

can try a slightly high pressure rad cap

i've always run my studs at 70 lb-ft, but opinions will vary

Mekkadon

iTrader: (3)

Overflow canister is not that big. About 1/2 the size of the stock one.
Looks like a small cylinder shaped canister or something. Wish I had a picture to show you. I just called the shop and they torqued them down to 100 ft-lbs all around.

Even if the canister is too small, it shouldn't be spraying coolant from it under boost, should it? I don't go WOT unit it is at operating temps (180-190 deg. F)

I hope it is not a cracked head.

Thanks for the input.

stevieturbo

Im taking a wild guess, that factory diameter albeit ARP head studs, would be bordering on their yield point at 100lbft ???

I torqued mine to 80lbft, which is higher than the 70 or so reccomended by ARP, but no way would I go to 100lbft ( with moly )

Everything you mention about your setup, sounds safe, so it looks like there is a mechanical problem of some sort.

Inspector12

iTrader: (29)

ARP instructions say 65lbs on the studs, but I do 70-80 depending on the what I feel like that day LOL! No real eveidence to show if the higher TQ helps or not I just feel that it might? And I agree with Harland on the cracked heads is a good possibility I would never think you should be lifting the heads, but you never know. Good luck.

ABeasst

iTrader: (5)

another possibility is that its the head gaskets. I have had 2 sets of cometics leak on a N/A motor which is why I dont trust them anymore and run MLS.

MIGHTYMOUSE

iTrader: (59)

the tune might be good now, but was there a time when it wasn't? this may be the result.

try some fresh gaskets and check the heads again.

Mekkadon

iTrader: (3)

Ahh, I see so is over-torquing the head studs actually hurting in gasket sealing?

Thanks. I will check the heads when they come off.

Wow, if they leak on a N/A motor, they sure won't hold up to a boosted motor it sounds like? I'll try swapping to MLS gaskets.

Will do.

Hopefully this will fix the problem. I will keep you guys updated (if you care. Probably not )

Pro Stock John

iTrader: (34)

Why not just try the MLS gaskets?

stevieturbo

I was suggesting, that if you tighten a bolt/stud/nut up too much, it can either stretch, or break.

If it has stretched, it will no longer clamp the way it should.

100lbft just sounds like a lot for a relatively small fastener. Although I guess it depends if moly or oil was used when torquing too.

Inspector12

iTrader: (29)

I guess I am blind cause I didn't see where he said what he TQ them too? I agree though 100lbs sounds line too much.

stevieturbo

In post #3

Inspector12

iTrader: (29)

OK I missed it wow what shop would go that far over the manufactures recomendations?

stevieturbo

If it was torqued with oil, rather than moly, the torque settings are higher.

But I would assume any shop would use ARP Moly, with ARP studs.

Mekkadon

iTrader: (3)

Are their sponsors that sell these type gaskets? I will have to order the 6.0L type MLS gaskets right? Just wanted to make sure!

Pro Stock John

iTrader: (34)

They are the GM ones. I'm just concerned since you are running not a lot of timing and not crazy boost either... something is going on.

Mekkadon

iTrader: (3)

I will be at the shop when the heads come off. I will be checking the block/heads as well.

I checked Thunder Racing (kick *** sponsor!) and saw that there were 2 part numbers listed:

20-12589226 GM Multi-Layer Steel LS1/LS6 Cylinder Head Gasket
20-12589227 GM 6.0L Multi-Layer Steel LS1 Cylinder Head Gasket

I am guessing that I need the GM Multi-Layer Steel LS1/LS6 Cylinder Head Gasket, like you said, since I'm running a LS1/LS6 style head and not LQ9s.

I just hope if something is cracked, it's the cylinder head. I'm not burning any antifreeze (no milkly stuff on the oil dipstick, not puffing any white smoke), so its not the block (right?)

Pro Stock John

iTrader: (34)

Post pictures of the gaskets.

y2khawk

iTrader: (5)

370 inch motor, that's 4.030 bore i'm assuming.

If so, you need to run the 6.0L gaskets or you won't seal a damn thing.

Mekkadon

iTrader: (3)

You are correct on the bore.

Thanks for the clarification!