blown cometic

[SIXBANGR]

or just leaking? Putting a little water in #1 and compression is down about 20lbs in that hole. Also leaking out the side of the head. has about 1300 easy miles on it.

[49-blues]

Did you try gm reseal tabs and retorquing?

[SIXBANGR]

Originally Posted by 49-blues

Did you try gm reseal tabs and retorquing?

yes I did. No change.

[SIXBANGR]

it did blow. 24lbs, 0 knock showing on the FAST. what gaskets do I use now?

[gnxtc2]

Originally Posted by SIXBANGR

it did blow. 24lbs, 0 knock showing on the FAST. what gaskets do I use now?

And how much timing,type of fuel, air temp, what a/f ratio, etc, etc

Billy T.
gnxtc2@aol.com

[gbsean]

where heads prepped with RA50....been issues without proper head and block prep

[SIXBANGR]

ra50 on heads and block. 10.94 A/F, 19 on the timing after 4200rpm, duel nozzle alky. heads torqued at 70lbs ,arp studs. Went to 80 to see if the leak would stop. RJC gaskets on the way. Car still ran pretty good.

[jpwalt1987]

several people (myself included) have had to take apart the Cometics and spray the layers with copper coat or hylomar. I have no leakage issues at all. hope this helps.

[SIXBANGR]

It blew the gasket, to late to copper coat it.

[TurboBuRick]

Can you snap some pics? Would like to see what a blown cometic looks like.

[GNDriven]

+1 on the pics, really interested, take a few macro pics if could. I can pass you my e-mail if it is easier.

[pacecarta]

no pics right now but to compare to a good gasket , it wont lay flat on the cylinder that let go , the metal stretches and warps

[TurboBuRick]

Hmm, got to make you wonder.

I've been running 25 psi and 25 deg timing for quit some time now with just 93 and Alky. I beat on the car daily. Afr's in the 10's. Been doing this for a couple years now.

Maybe there is a problem with the one injector. What cylinder blew?

Are you using head studs?

[SIXBANGR]

here you go. head studs, 83lb inj.Number 1. Bad gasket? Bad luck?

[TurboBuRick]

WTF?

[ttypewhite]

I would flow test your injectors and have a look at your spark plugs wires.

[SIXBANGR]

Originally Posted by ttypewhite

I would flow test your injectors and have a look at your spark plugs wires.

who does the inj., and how much?

[jasjamz]

Chuck Leeper

[Scott Atk]

Were you using oil or ARP lube when torquing to 70 lbs. If using oil 70 is a little low. Although I doubt that's your problem. As stated have injectors flow checked also check the injector driver in the ECM.

[SIXBANGR]

ARP lube. Just pm'd Leeper. Using a classic FAST.

[gbsean]

Originally Posted by pacecarta

no pics right now but to compare to a good gasket , it wont lay flat on the cylinder that let go , the metal stretches and warps

Originally Posted by SIXBANGR

here you go. head studs, 83lb inj.Number 1. Bad gasket? Bad luck?

does head sit flat on block without gasket....just thinking you might of had same issue I did with the block stud not fitting into head hole all the way....and gasket blew out under higher boost level...it just distorted the ring enough to allow water in and boost to escape....

[TurboBuRick]

When you remove the injectors, mark each one with the cylinder number it came from.

[DonWG]

I wouldn't be blaming the gasket on that one. It appears you lost clamping force for whatever reason. A tuning issue, most likely. How much has been taken off the head surface? How thin are the deck surfaces?

[Otto J]

Double check the head studs/bolts to be sure they are tightening down properly and not bottoming out,That was not the gaskets fault

[SIXBANGR]

Originally Posted by DonWG

I wouldn't be blaming the gasket on that one. It appears you lost clamping force for whatever reason. A tuning issue, most likely. How much has been taken off the head surface? How thin are the deck surfaces?

heads were milled .003. It was a non machined na109 block that I just had done 3 months ago. FAST shows nothing wrong. The inj are ready to ship, just have not heard from Chuck yet.

[SIXBANGR]

Originally Posted by Otto J

Double check the head studs/bolts to be sure they are tightening down properly and not bottoming out,That was not the gaskets fault

it has studs right now. For some reason I have never had good luck with them.

[gbsean]

again double check that head seats all the way down on block without the gasket in place...

[SIXBANGR]

Originally Posted by gbsean

again double check that head seats all the way down on block without the gasket in place...

just checked, it is perfect.

[Razor]

Originally Posted by SIXBANGR

It blew the gasket, to late to copper coat it.

And too late to re-torque it. being its number 1 and not 3,, its probably from not enough tq on the stud.

85 ft lbs is what most of us use.

[gbsean]

85 here and re-tq after first startup....You have Pauly in your corner....what does he say about the failure

[SIXBANGR]

#6 looks like it was going to go next. When I looked at the plugs a few days be for, 1 and 6 looked rich.

[SIXBANGR]

Originally Posted by Razor

And too late to re-torque it. being its number 1 and not 3,, its probably from not enough tq on the stud.

85 ft lbs is what most of us use.

and when I researched it 3 months back it was 50/50. So i went with 70 figuring I could always go more. It's like head bolts or studs. About 50/50 there also.

[Razor]

Originally Posted by SIXBANGR

and when I researched it 3 months back it was 50/50. So i went with 70 figuring I could always go more. It's like head bolts or studs. About 50/50 there also.

I hear ya. The problem is if the TQ is low, you dont have as much clamping and the slightest lift.. pooof goes the gasket. On the other side, if you go to high you can distort the block. And re-torquing a gasket thats been zinged.. doesnt correct it. Those Cometics when they go.. they slightly breach.. cuasing overheating and performance issues. The stockers.. once they go.. no in-between.

One of my buddies goes 85 on the top and 80 on the bottom. His feelings.. Its always better to blow the gasket down than up. Then you get X amount with oil and X amount with ARP lube. I lube the threads, washers and three steps to 85. 40/60/85 But thats just me

[DonWG]

Originally Posted by Razor

I hear ya. The problem is if the TQ is low, you dont have as much clamping and the slightest lift.. pooof goes the gasket. On the other side, if you go to high you can distort the block. And re-torquing a gasket thats been zinged.. doesnt correct it. Those Cometics when they go.. they slightly breach.. cuasing overheating and performance issues. The stockers.. once they go.. no in-between.

One of my buddies goes 85 on the top and 80 on the bottom. His feelings.. Its always better to blow the gasket down than up. Then you get X amount with oil and X amount with ARP lube. I lube the threads, washers and three steps to 85. 40/60/85 But thats just me

Razor. Is that 85 with ARP lube?

[jpwalt1987]

When I asked Dan @DLS about stud torque he told me 70ft/lbs on all the studs. That is with ARP lube.