TurboGibbs

iTrader: (6)

Ok, the specs on this engine at the time of failure is:
370 ci
9.0:1 comp, 223/218 114 cam
front mount PT76-gts FMIC
L92 heads stock
6psi
16* timing
10.5:1 afr
ARP studs tqed to 70lbs with arp moly lube

Only about 1000 miles on engine, O-ringed block, and SCE solid copper .040" gaskets. From the markings it looks like they have been blowing by more than once.
Heads and block were checked flat and hand stoned before assembly and oringing.
As a note, previously I had 317 heads with all the same specs above but 13psi and 11.7:1 afr and when I pulled the heads they factory MLS gaskets had been blowing by on the center two cyls as well with ARP bolts.
Does this look like a common problem with factory heads that only have a 3/8" deck? Is the only fix for this aftermarket heads with a 3/4" deck? I'm plum fed up.

1badnova496

iTrader: (19)

i say ditch the turbo and and up the compression and go with a different cam and have tons of fun

MIGHTYMOUSE

iTrader: (59)

i wondered if those heads were gonna be weak... mabey so. only 6# hard to believe any trouble like this

1slow01Z71

iTrader: (36)

You suck at life IMO

TurboGibbs

iTrader: (6)

My prognosis is they are a great NA head, so that is what I will make them. I'm not spending $2500 on AFR's. Anyone want a front mount turbo kit for a truck?

TurboGibbs

iTrader: (6)

You know what you can suck at.

yomama

iTrader: (9)

Looks like there were a couple of things i would be weary of, it looks like those heads still have the swirl marks from the decking, if so they dont have a smooth enough finish for the gaskets to seal. Second did you retorque those head gaskets after the first heat cycle? Those kinds of gaskets should be retorqued. Other than that everything looks right but those are the most common spots for any head gasket to blow i wouldnt chalk it uo to just an l92 problem.

TurboGibbs

iTrader: (6)

The factory facing marks were somewhat noticable. I stoned the hell out of them and the divits or waves you may see I would estimate to be no more than .0005" deep if that. There is just enough there for discoloring and you can't hardly feel them with your nail. I doubt they affected the seal of the oring. There is more variences in the oring from dinks or marks when the wire was installed.

1slow01Z71

iTrader: (36)

Sell me your turbo Ill even pick it up from your

TurboGibbs

iTrader: (6)

If it is sold it will be sold as a kit.

TurboGibbs

iTrader: (6)

I just double checked the heads and block for flatness and I can't slip a .003" sheet of paper under the straight edge.

cncbird

iTrader: (3)

head surfaces really do look too rough--you can even see swirl marks from the heads on the gaskets

TurboGibbs

iTrader: (6)

Even if so, the applied pressures over an area average out to be the same as a finely ground surface+ the breech points are 1.5" long, not the .025" of the low spots. You do the math.

LASTLS1

iTrader: (7)

Did you re torque the heads after the first heat cycle?????

black98ws6ta

iTrader: (77)

How much does the wire protrude ? Did the gaskets blow on both side of the gasket or just one(block/head side)?

EDIT:looks like both sides

TurboGibbs

iTrader: (6)

I spot checked a few I could get to and none of them budged at 70lbs. ARP recommended 65 with their lube, I torqued to 70 initially.

TurboGibbs

iTrader: (6)

gasket blew on both( you can see that in the pics) and my best guess ( i haven't measured) protruding .015-.020" from my machining experience and eyeball.

black98ws6ta

iTrader: (77)

The wire should only be protruding no more then 25% of the total thickness of the copper gasket. If your boost/timing is where you say it was and there arent any backpressure issues or anything I cant understand why your old or new set-up should be blowing. If you have a .015-.020 and a .040 gasket, you need to go to a thicker gasket for them to be used correctly.

LASTLS1

iTrader: (7)

Well that's a BIG problem. You have to let the engine warm up to full temp 200 deg. Then let the engine cool completely off, then loosen each nut a half a turn and retorque! Only do one nut at a time using your normal torque pattern. If you don't do that your copper gaskets will NEVER seal!

If you mark each nut before you loosen it you will be suprised how much further they will turn.

SuperZ

iTrader: (2)

dang I hope its not the heads.I have a set of these for my next motor.....anyone know any more about these