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
Blown head gasket
- Thread starter hwy2
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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
TT5.9mag
Two atmospheres are better than one
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.
MOPAROFFICIAL
Oogliboogli
Pushed into the valley?
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.
TT5.9mag
Two atmospheres are better than one
It’s indicative of the weakest point of clamp load on the gasket.
AJ/FormS
68 Formua-S fastback clone 367/A833/GVod/3.55s
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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.
Newbomb Turk
Well-Known Member
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.
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.
Mikethegreat
Member
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.
Kendog 170
Let the boy go !
I would like to run .020 gaskets on my 340 to bump up my compression but worry about leakage.
Factory was a .020 steel shim gasket. I’ve used them many a time with cast heads. Kim
Kendog 170
Let the boy go !
Yes I had them before the rebuild. Where are they now? Obsolete I'm thinking. Any links?
I think there is some Mr. Gasket ones still out there.
TT5.9mag
Two atmospheres are better than one
Did you come to any conclusions as to why it pushed the gasket out?
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