I need to buy head gaskets for my pretty high boosted LT1.
What head surface prep needs to be done with cometic gaskets?
Do I need to use a spray sealant also?

 

so i have owned my lt1 for over 3 years and have had to fill my coolant system numerous times for waterpumps, multiple optis, heater core, hoses, rebuild, etc etc. i came into all this work on my car with next to no work ever done on a car before besides handing tools to my dad or someone else. i did however know to be very cautious and watch the temp gauge constantly. after finding out about the bleeder screws which seemed odd to me at first i had no issues. my ultimate point being maybe these cars have had mild work done by their not so knowing owners and maybe air pockets were left, makes a lot of sense to me as to why these older cars(needing routine maintenence for their age) are coming in with blown head gaskets. the not so well versed trying to learn and making a detrimental mistake with their babies. i know i am not the only one who got in way over their head buying a fun toy without any real knowledge or experience or money to get things fixed by properly trained professionals. this site has answered so many of my dumb questions (and continues to do so) and helped me learn so much and learn to half way enjoy wrenching, never thought i would ever say that. was that long winded enough, surry

 

I put the surface finish at 15-22ra for MLS gaskets - this is where the OEM specifies that the surface finish needs to be for their gaskets to seal on motors made by Toyota, Honda, GM, and Ford(dealerships whom I do lots of machine work for). Cometic on the other hand keeps lowering the standards for surface finish, when they were first introduced, 30ra was the spec, then a few years ago 40ra was the new numbers, recently I have seen 50ra being passed around. I have seen them leak at anything over 30ra unless copper coat is used so I have a hard time swallowing their information.

 

machinest,
what head gasket do you recommed as a stock replacement? When a gasket blows is it a given that the head will need to be surfaced?

 

ditto. WOT @ 5000+ RPM @ 80+ MPH doesn't leave much time to shut things down

 

The fel-pro replacement gasket does a fine job.

Pretty much any time the head gasket goes on those motors the heads need to be surfaced, it's most common to see the blow at the back cylinders to the water port where there has been surface erosion of the aluminum leading to combustion gasses in the coolant. You will find pitting and tracking on the aluminum that would just lead to another blown gasket if the heads are not surfaced, in other words unless you are pushing serious cylinder pressures - gaskets don't just blow for no reason, the underlying problem needs to be fixed which is generally a damaged head surface or warped head from overheating.

 

thanks, any specific surface roughness spec needed for the heads using the felpro 1074 gasket? Is it safe to expect the machine shop to know what level is needed? I only want to do this once.

 

Some shops are still not equipped to machine surfaces for MLS gaskets, but any machine shop that cannot machine a head for an LT1 composite gasket should not be in business. That being said - the desired surface finish for late model thin castings with dissimilar metals is 30-60ra.

 

thanks, great info.

 

I would be willing ot be on the blown head gaskets that are not still bolted down from the factory, its the regular but unwise policy of re-using the head bolts. They are designed to only be used once then replaced. Their strech design would cause them to not keep even pressure resulting in gasket failure. Solution is new (never been used) bolts, or ARP bolts. You don't need the stud kit, the ARP bolt kit is $60 and has worked in several single digit cars, so street cars are no problem. my $.02

 

I know I'm not directly answer prior message, but wanted to check on the same subject. I have radiator fluid in the #3 cylinder, compression good at 190 psi @ 7 cranks. Steam rolling out of tail pipe, contaminated oil. Blown gasket right?

I'm pretty handy with my Z28, but I think this one is over my head. Question - should I have a certified engine overhaul shop do it? Or do you think getting a guy of a friend who knows how to do (or even Craigs list) is sufficient. I don't have 2500+ for a certified dealer/full service station to do it. I really don't want to pay more than $1000 to have it repaired.

Does anyone have a suggestion for a place in the Bay Area, CA? Thanks...

 

The later yeatr LT1s had TTY bolts but the earlier ones did not. This sort of thing happens a LOT where people hear something and then assume it applies to ALL rather than just some.

 

So does this mean that, on my engine for example (97 LT1), reusing the head bolts would be acceptable?

 

I said later years were TTY and your's is the LAST year the LT1 was made.

How did you get the idea that your head bolts would be reusable from that?

Maybe you don't know TTY is Torque To Yeild, yeild meaning stretch and don't reuse.

 

Can you reuse the arp head bolts?