90Indy

My 90 L98 with approximately 5,000 miles on a head/cam installation failed. The #3 cylinder was filled with coolant. I hope the pictures I took will post here.




Take a look and if you have had a similar failure what was the cause? The bolt hole on the far right side is completely burned through. I was very careful when removing it so the damage you see is exactly the way it looked on the block when I removed the head. The other half of this gasket is fine as is the entire gasket on the passenger head.

Any input is much appreciated.

90Indy

trackman44

What's the compression ratio and what gasket did you use?

90Indy

The gasket maker is Corteco and the compression ratio is 9:1. I have 5 dyno runs on the engine after the installation of an 8 psi blower with gaseous intercooling. The dyno runs were made during the tuning and chip burning. I don't think the blower did anything but possibly hasten the gasket's demise. In looking at it I think it was heading towards failure for quite some time.

I had about 5,000 miles on the motor before the blower and less than 100 after. I spoke directly to the gasket maker and told them about my blower plans. I was told this gasket would handle the blower.

90Indy

Pete K

When you assembled the engine did you use new head bolts?
If so I have a possible theory

90Indy

Hey Pete,

Yes I did use new head bolts -- ARP's. I torqued them with a click type calibrated Snap-On Wrench. I went only in 5 lb/ft increments and used the pattern shown in the GM Manual. The one thing I did not do was retorque as the gasket maker told me it was not necessary.

90Indy

Pete K

http://forums.corvetteforum.com/show....php?t=1785319
Stan,
Take a look here. Good info inside.

trackman44

Go with a thicker gasket ( say 0.041). It'll lower the compression ratio a bit more so that the gasket can handle the higher pressures in the combustion chamber due to the blower.

90Indy

I guess I am guilty as charged. I used new head bolts and did not "roll" them before installation. My question is can I reuse the head bolts and consider them "rolled"?

Just to see if any head bolts were loose, I tried to snug a few of them prior to removing them. None that I tried to tighten seemed loose. I did not, however, put a toque wrench on them.

Also, do I need to retorque after a few heating/cooling cycles?

90Indy

Pete K

I would bolt everything back together, loosen each bolt and tighten it 5 times. Then, when the motor goes back together, they can be cleaned, lubed under the head and on both sides of the washer, then have sealant applied. Torque and they should be fine. Although head asket manufacturers do not require retorquing, it is always a good idea.

chucks88

Oh sure.......kick a guy when he's down

96GS#007

If you call ARP they'll tell you that as well.

Pete K

No offence intended.
I actually started it. I had an engine builder I no longer use install main studs and rod bolts in a fresh motor. He did not roll in the threads. I double checked the main bore dimensions and the rod big end dimensions. Because they were fine, I proceeded to mock up and clearance my stroker motor. Because I assembled, and disassembled everything 5 times, "I" was the one who rolled in the thread(unknown to me).
This caused the final finished machined dimensions(line hone on the mains and rod big ends) to crush the bearings .001 tighter.
Motor lasted 150 miles before it ate itself up.
Because they checked well the first time I checked, I put it out of my mind.
I lost that motor and almost nothing was saved. Expensive day, for sure