The valiant blew its head gasket at the track yesterday. I was surprised since we were only running 6 pounds of boost. It happened mid track and still ran 15.3 @ 95 mph.

A friend was kind enough to trailer it home for us.

I will research this, but if anyone has any suggestions I am all ears.

Gasket brand? ARP studs? Torque spec?

I will never run this can over 14 PSI and may not even go over 6 PSI since the car can't hook up where it is now.

All steamed up,
Barnaby

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These ones go to eleven...

I can't this out of my head... Pun intended!

https://www.youtube.com/watch?v=a5R_pS0h5Qk

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These ones go to eleven...

What gasket did you have on there? At 6lbs, you should not have head gasket problems. I would look at the "tune up". You most likely got into detonation. When I first did my turbo, I had problems with head gaskets at 10psi. Kept working on the gasket problem. Different brands, new bolts, etc. Finally "O"-ringed the block, and used a copper gasket. That cured my gasket problems. Then I started eating pistons. My tuneup was way off. I was getting into detonation. With the "lesser" gaskets, the gasket was acting like a "fuse" and saving the rest of the engine. I would much rather change head gaskets, then pistons.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

I don't think it is detonation. We have spent a lot of time tuning it including dyno work. I believe the gasket was Felpro at stock torque specs.

If it was detonation There were no audible signs. Would there be any tell tails when I pull the head?

I also thought that the waste gate failed and we ran more boost, but the time slip did not reflect this theory.

I am open to copper and o-ringing. I was told that copper gaskets can be difficult to install. But again 6 psi is nothing, still scratching my head???

B

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These ones go to eleven...

If there are any marks around the edge of the top of the piston it is detonating. You'll know it when you see it.

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Official Cookie and Mater Tormentor.

Bummer,
Couple things come to mind. Head gasket itself ,you indicated felpro.
Is your bore standard? If its .040 or 060 over bore gasket will hang into bore , this is a NO NO.. I have blown naturally aspirated with gasket hanging into bore.
Add zero or close to zero deck (even with dish piston) and its all over with.
Compression? Obvious question, not all detonation is audible. Not all pinging is audible. Detonation does NOT hurt power in a lot of cases.
Point I am making here is you could be tuning to the best detonation.
Ask a snowmobile racer "Man it was running good when it locked up"
AFR? these things have really crappy manifolds and you could be reading
11.5 and have one cylinder in 16.s @ a certain RPM, May not even hurt the piston but cut the over hanging gasket instantly like a torch.
Hydraulic ? did you leave the key on? Even a mild hydraulic can displace a gasket and it may finish slipping @ any time.
Over all with proper gasket (same as yours) torque (stock bolts)
7.8 to 1 compression 20 degrees Total timing and 87 octane I have
Have run 10>12 psi and had 2 year long run of daily driving.
10 gal an hour water meth injection and 1/2 degree (per) boost retard
are merely failsafes and NOT mandatory although you need to have
Something. JMHO Godbless

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" Inventor of 24 grit wart remover"
http://i1369.photobucket.com/albums/ag2 ... 06715e.jpg

Thanks, I'm 60 over and I never considered the possibility of combustion damage on the gasket. I have water/meth injection, but have not turned it on. I had the car dyno tuned at PSI and these guys do a lot of turbo casr and have a solid reputation. They convinced me that I was better not to use the injection at 6 pounds and that my tuning was conservative.

I hope my fuel distribution is somewhat even. I have the Aussie Speed long runner intake, but perhaps my exhaust back pressure is not?

I'm probable putting the cart before the horse since I have not had time to get into the engine, should I get a copper gasket? Even if that was not the issue, it would give me more room to up boost.

8.77:1 compression, 6 pounds, Buick GN T3, inter-cooler,

Cheers,
Barnaby

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These ones go to eleven...

I have blown exactly one Slant 6 head gasket in the last 26 yrs of engine beatings.

It blew between #4 and 5 cylinders on the 68 Turbo Dart on 6-9 psi for ~5k miles and 30-50 drag passes. The gasket fire ring was hanging into the valve seat relief area and so was in the fire all the time. I got a bit greedy on the tuneup at Bristol (before water/meth inj system) and blew it. When pulled, the gasket had heat damage on 3-4 cylinders, all where the ring overlapped the combustion chamber under the valve. I went to the big 3.66" bore Aussie gasket and have had no further trouble up to 11 psi. 50+ drag passes and about 10k miles so far. Gasket does not get close to the combustion chamber anywhere.

Hope this helps,

Lou

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Home of Slant6-powered fun machines since 1988

Thanks Lou,

I'm hoping that is what happened to my engine. I need to inspect, and a smoking gun is preferable to head scratching.

What was the turnaround on the Aussie Speed gasket?



B

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These ones go to eleven...

I ordered a bunch in a group buy years ago, and I have never bought from Aussiespeed.

Lou

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Home of Slant6-powered fun machines since 1988

If that is the AP-210 gasket I have one I would let go of. I ended up with a couple from Frank Brent when Rick did the group buy a couple years ago.

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Official Cookie and Mater Tormentor.

Awesome! I will send a PM.

B

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These ones go to eleven...

PM answered.

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Official Cookie and Mater Tormentor.

I am bringing a few back from Australia too...

Lou

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Home of Slant6-powered fun machines since 1988

I Finally got into in. The gasket was compromised on #2. No detonation, but my torque was off and possibly the some of the bolts were compromised.

I'll upgrade to the Aussie gasket and ARP studs.

B

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These ones go to eleven...