I am running across a lot of F body LT1s with blown head gaskets, and after so many years of dealing with bullet proof 1968 up small blocks am amazed at how many are out there. What is the deal with it? Bad gaskets from the factory? Bad bolts? I know the expansion rates of iron and aluminum are different but you would think the factory could get around it. When fixing this what can I do to make sure this does not happen again? I have a few engines that need gaskets and planned on using felpro 1074 gaskets and ARP head bolts. Do the heads usually warp when the gasket goes?

 

I blew my head gasket last friday. Had my z28 for a about two months. It was a felpro gasket. When my dad took the head off, he noticed that the bolts on the head weren't tight at all...

Same with my water pump 2 weeks ago, the driver's side 3 bolts were finger tight on it.

So I'm guessing whoever last did work on the engine didn't torq the bolts right.

Other than that I've had good luck with felpro, but I dont know about them with the LT1 engine.

 

well in your case whoever did the repair either tried to resuse the original torque to yield bolts or just didnt own a torque wrench..

I am talking about factory engines that blow the gaskets, just seems to happen an awful lot, when I deal with the earlier iron head engines I never saw a blown gasket.

 

well i think some LT1s had Aluminum heads. And Aluminum heads expand more to heat the iron.. I think the F-body cars got the aluminum heads and the others got the cast iron.

 

fbodire and vettes got the aluminum heads, and the b-bodies got the irons. But probably the big reason why you see a lot of factory stock motors blowing gaskets is because the temps for the fans to come on are set pretty high, and that the coolant system has a little different method to fill to be sure there are no air bubbles. Or it could just be that the cars are getting older and people aren't taking care of them like they need to.

 

I would agree with that.
It is an extremely rare occurance for the iron head LT1s to pop a head gasket so I think the aluminum/iron combination is a part of it but then they also got different gaskets so I suppose you can't dismiss that as a possibility either.

 

Properly assembled, they don't have problems, unless they overheat severely. I'm running a 300-shot of nitrous, with no head gasket problems. A buddy of mine ran over 20# of boost and made 1,125HP at the flywheel with an iron block/aluminum head LT1.... and no head gasket problems.

If it is the problems with deaerating the reverse flow cooling system (and I think that's a valid concern), I would expect to see the F-Body LT1 installs fail a lot more frequently than the Corvette setups, because the Corvette coolant system is designed to self-eliminate the air, with a pressurized coolant reservoir at the high point in the system. Interesting to see if the Corvette owners have the same head gasket failure rate, but I doubt we have enough Corvette LT1 owners here to be a meaningful sample.

 

So are you agreeing with the OP's claim that there is a high failure rate of stock factory headgaskets on stock factory shortblocks?

I certainly haven't gotten that impression in my 7 years in the LTx world.

 

Myself it seems like a high failure rate, only because out of the 25 to 30 LT1 cars I have had over the last two years I have had 6 F bodies that had blown head gaskets, and a few that had blown them and then spun a rod bearing from coolant in the oil. All were aluminum head engines, I have had no issues with the iron head LT1s.
Some engines have known factory issues, for example bad intake gaskets on the v6 3100 engines, and I just wanted to know if the factory used substandard head gaskets on these cars, didnt machine the head faces right, or used bad bolts.

 

Read what I posted carefully. I did not agree with the OP.

Directionally, overheating causes blown head gaskets. The F-Body LT1's reverse flow cooling system is prone to overheating, IF THE SYSTEM IS NOT FILLED, BLED AND OPERATED CORRECTLY.

I've owned my car for 14 years, and been on F-Body boards here and other places, for well over 10 years, and my initial reaction to the OP was "what high failure rate?". I personally do not know an F-Body LT1 owner who has blown a head gasket. But.... if overheating blows head gaskets (and overheating is a problem with dissimilar metals), the cooling system - OPERATED INCORRECTLY - would exacerbate the problem.

I don't have enough statistical data to state one way or the other whether the LT1 has a higher head gasket failure rate than the Gen 1 SBC. But I thought my comments might contribute to the discussion.

 

Dissimilar metals - you will find it much more common to have blown head gaskets on motors with an iron block and aluminum heads that use a composite style gasket. MLS gaskets were partially designed to directly attack this problem - they allow the head and block to grow at different rates and not eat the gasket.

 

Which is also a problem tied to STREET driving a car, wont really show up on a racecar so much. Not enough heat cycles.

The point Injuneer made about the pressurized tank on the Vette also applies to the b-body and seem like a good point.

 

so what would be the best head gasket to use? I thought the felpro 1074s were recommended but I believe they are composite.

 

cometic
or remflex

 

Arent cometics only needed for boosted applications? I am talking stock engines, at the most a mild cam, no boost or mods.