Blown head gasket

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hwy2

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Seems I blew a head gasket. Loosening head bolt I noticed two close to the break in gasket were looser than the others. My set up has 11:1 compression with .039 compressed head gasket. I have cometic but they are .020 and will raise compression to 11.6:1. I have aluminum heads. Will this be an issue with 93 octane. It’s a 318/392 thumper cam. .513 lift intake
 
Check the deck of the block with a good straight edge and feeler gauges, also the mating surface of the head.
 
Check the deck of the block with a good straight edge and feeler gauges, also the mating surface of the head.
Do you ever re-torque? And I used a feltro gasket before. The cometic in multi layered. I’ll check tomorrow with a feeler gauge
 
I always check and recheck my torque, especially since I'm old and have CRS. LMAO
 
You have to figure out why it’s pushing out the gasket. There IS a reason. If it’s detonating because you have all the timing in it way too soon or something like that then adding compression will make it worse. Even with a better gasket. Only you can know if you can make 11.6:1 live on pump gas. It takes careful tuning and set up.
 
Cometic type gaskets require a very fine finish on the surface to be sealed.....or they will leak.
If in doubt, use a conventional gasket such as Felpro.
 
Does that indicate anything
That's usually where they fail from too much cyl. pressure/boost/detonation. We had FelPro HP's on a 340 & ran it up to 21#'s of boost w/water-meth injection, it had higher grade cap screws than stock, and torqued evenly in steps...left to sit & re-torqued 2×. Never blew a gasket again, even when the water injection failed & detonation collapsed a ring land on the TRW blower piston.
Figure out what's going on.
 
Seems I blew a head gasket. Loosening head bolt I noticed two close to the break in gasket were looser than the others. My set up has 11:1 compression with .039 compressed head gasket. I have cometic but they are .020 and will raise compression to 11.6:1. I have aluminum heads. Will this be an issue with 93 octane. It’s a 318/392 thumper cam. .513 lift intake
My 367 has run at up to; 11.3Scr/9.2Dcr/190psi with alloy heads, @.032Quench. I run a 2-stage timing curve; 12>14@ Idle, going to 28*@2800, then 32/34 by about 3400. This allows me to run 87E10 full-time. I run the 039 FelPros, with ARP bolts torqued to 105 in stages, on the ARP grease, with no retorque. In ~2005, I replaced the cam, redecked the block, and subsequently the Scr changed to 10.95, the Dcr to 8.9, and the pressure to ~185.
Your results may vary.

BTW
This change was deliberate. I gave up top-end power to gain bottom-end torque for my 4-speed/3.55s combo..
 
My 367 has run at up to; 11.3Scr/9.2Dcr/190psi with alloy heads, @.032Quench. I run a 2-stage timing curve; 12>14@ Idle, going to 28*@2800, then 32/34 by about 3400. This allows me to run 87E10 full-time. I run the 039 FelPros, with ARP bolts torqued to 105 in stages, on the ARP grease, with no retorque. In ~2005, I replaced the cam, redecked the block, and subsequently the Scr changed to 10.95, the Dcr to 8.9, and the pressure to ~185.
Your results may vary.

BTW
This change was deliberate. I gave up top-end power to gain bottom-end torque for my 4-speed/3.55s combo..
I got those gaskets. I will increase torque to 105. I am at 95 now. Hand tight then 50,70,95. I have same arp studs.
 
Fix your timing curve.

Double check your plug heat range.

Get your coolant temp down to 160.

You’ll have plenty of octane for that compression ratio.

Octane is one of the most misunderstood tune up variables I can think of.
 
Seems I blew a head gasket. Loosening head bolt I noticed two close to the break in gasket were looser than the others. My set up has 11:1 compression with .039 compressed head gasket. I have cometic but they are .020 and will raise compression to 11.6:1. I have aluminum heads. Will this be an issue with 93 octane. It’s a 318/392 thumper cam. .513 lift intake
A small block Mopar has 4 bolts per cylinder to a small block Chevy "s 5 per cylinder. It has less clamping force. I blew a few on my race car. The fix was to stud the block and use Fel Pro O ring head gaskets. The standard Fel Pro does not have a Oring in it.
 
Lots of engines have 4 bolts per cyl, Fords, Pontiacs, etc & do not blow head gaskets.
 
I would like to run .020 gaskets on my 340 to bump up my compression but worry about leakage.
 
Replaced with felpro not blown so far. Retorqued and retorqued 100ftlbs
 
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