Hopefully the 3rd time, will be a charm. 
Update on Blown head gaskets
Thread Starter
Safety Car
Joined: Oct 2001
Posts: 4,763
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From: Connectivette
Update on Blown head gaskets
It's happened again since this....
http://forums.corvetteforum.com/show....php?t=1785319
However after going through the rigors of "Rolling-in" the bolts and practicing due diligence it had happened again back October. After removal of the heads both gasket rings were distorted with a couple of the passenger side gaskets rings almost completely tearing away from the fibre portion of the gasket.
This time I dropped the heads and gaskets of at the shop who built my shortblock. He and his crew had never seen gaskets fail like that....especially on a naturally aspirated engine with only a moderate C/R of 11:1
The Felpro rep picked up the gaskets the next day from the shop and sent them off for eval. As soon as I find out what's going on...I fill you guys in again.
http://forums.corvetteforum.com/show....php?t=1785319
However after going through the rigors of "Rolling-in" the bolts and practicing due diligence it had happened again back October. After removal of the heads both gasket rings were distorted with a couple of the passenger side gaskets rings almost completely tearing away from the fibre portion of the gasket.
This time I dropped the heads and gaskets of at the shop who built my shortblock. He and his crew had never seen gaskets fail like that....especially on a naturally aspirated engine with only a moderate C/R of 11:1
The Felpro rep picked up the gaskets the next day from the shop and sent them off for eval. As soon as I find out what's going on...I fill you guys in again.
Thread Starter
Safety Car
Joined: Oct 2001
Posts: 4,763
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From: Connectivette
I guess we don't read the same books... 12:1(approx.) to me would be the upper limits(pump gas)....10:1(approx.) on the lower side of what some would want on a performance rebuild........11:1 ...right in the middle
I am running AFR 190's
Team Owner
Joined: Oct 2004
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From: Bergen County, NJ Democrats, doing for the country what they did for Michigan
Off the top of my head you were running 9.5 stock. I think the stock gasket was .051 (if I remember right)
So all things remaining equal (the pistons) combined with the smaller gasket and the smaller heads.
My seat of the pants WAG puts you out in front of 11:1. Seems it would be higher.
Team Owner
Joined: Jan 2003
Posts: 20,306
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From: Summerland B.C. Canada
I'm, using the 1010's at 10.5 compression and I run it pretty hard. No issues yet, but you have my attention now.
My block is decked and the heads resurfaced, I can't ask for better chances.
My block is decked and the heads resurfaced, I can't ask for better chances.
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Thread Starter
Safety Car
Joined: Oct 2001
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From: Connectivette
My C/R was calculated by my engine builder(he built short block only) However he did have my heads while he was machining/assembling it and calculated accordingly. I suppose his math could have been off.
I thought out stock L98 heads were at 58cc's I can't recall but I think the AFR's were close to that....maybe 56cc's
I thought out stock L98 heads were at 58cc's I can't recall but I think the AFR's were close to that....maybe 56cc's
Last edited by chucks88; Dec 6, 2007 at 11:24 PM.
Team Owner
Joined: Oct 2004
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From: Bergen County, NJ Democrats, doing for the country what they did for Michigan
My C/R was calculated by my engine builder(he built short block only) However he did have my heads while he was machining/assembling it and calculated accordingly. I suppose his math could have been off.
I thought out stock L98 heads were at 58cc's I can't recall but I think the AFR's were close to that....maybe 56cc's
I thought out stock L98 heads were at 58cc's I can't recall but I think the AFR's were close to that....maybe 56cc's
Thread Starter
Safety Car
Joined: Oct 2001
Posts: 4,763
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From: Connectivette
Team Owner
Joined: Oct 2004
Posts: 35,065
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From: Bergen County, NJ Democrats, doing for the country what they did for Michigan
Le Mans Master
Joined: Oct 2003
Posts: 6,130
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From: seattle WA
Read your old thread, and this new one. Re-torquing head bolts after run in (or bringing it up to operating temp) has been called old school by alot of forum members...and I'm one of the old schoolers. I've always followed the torque pattern and did them in stages, 3 times is fine. But I've always re-torqued them after getting it up to operating temp....PIA, but better than what you're going through. Make sure nothing is warped, and this time re-torque. Hope it works out. And I wouldn't worry about the CR, doubt if 11:1 has any affect on your problem.
Thread Starter
Safety Car
Joined: Oct 2001
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From: Connectivette
Read your old thread, and this new one. Re-torquing head bolts after run in (or bringing it up to operating temp) has been called old school by alot of forum members...and I'm one of the old schoolers. I've always followed the torque pattern and did them in stages, 3 times is fine. But I've always re-torqued them after getting it up to operating temp....PIA, but better than what you're going through. Make sure nothing is warped, and this time re-torque. Hope it works out. And I wouldn't worry about the CR, doubt if 11:1 has any affect on your problem.
What did I type in this new thread to lead you to believe that I did not re-check the torque values of my head bolts after a few heat cycles and/or follow the correct torque pattern/sequence in 3 stages. (which I actually did in 5 stages starting with 25 ft. lbs.)
At any rate 2 of us checked the heads and the deck surface with a straight edge.....and as far as we can tell....she looks good. Thanks for all the suggestions....keep 'em coming.....I probably won't act on too much of yet however as I would like to hear back at what Felpro has to say.
One question run passed me by one of the guys in the shop of my engine builder was.......If I had any issues with the intake base fitting on the heads.....holes lining up, difficulty starting the bolts. ETC. I guess his thinking was that it could have caused the some stress on the heads. But I had no such issues.
Intermediate
Joined: Aug 2007
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From: Raleigh NC
OK, I'm no expert but I really liked this guy's articles on the subject of head gaskets and their failures. http://www.aa1car.com/library/gasket_failure.htm
One thing mentioned in the article is how smooth an aluminum head surface must be when using composite gaskets. The recommended surface finish for aluminum is 20 to 50 RA which compares to 60 to 120 RA for cast iron. 20 RA is a mirror-like finish. Is it possible that the head surface isn't smooth enough because the gasket you show looks like a lot of brennaling(sp?) going on.
I recently put new heads and gaskets on my L98 using Felpro 1010's. It's pretty much stock and I've got about 500 miles on it so far with no problems. So I have a very strong interest in your saga.
One thing mentioned in the article is how smooth an aluminum head surface must be when using composite gaskets. The recommended surface finish for aluminum is 20 to 50 RA which compares to 60 to 120 RA for cast iron. 20 RA is a mirror-like finish. Is it possible that the head surface isn't smooth enough because the gasket you show looks like a lot of brennaling(sp?) going on.
I recently put new heads and gaskets on my L98 using Felpro 1010's. It's pretty much stock and I've got about 500 miles on it so far with no problems. So I have a very strong interest in your saga.
Thread Starter
Safety Car
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From: Connectivette
Thanks for the links. No word yet back from my builder. So it's still in Felpro's hands at this point. after some searching on Google, I was unable to find pics of blown head gaskets that look like how mine failed.