I recently picked up some gm vortec heads, along with a summit intake. Now, I have read numerous different threads on numerous different forums about this, and I can't seem to get an actual answer. Everyone says to use the factory gm ones, but to stay away from plastic, which is what the gm ones are? Some people say the Felpro 1255 will work, while others say spend double the money and get the felpro MS98000-T because the 1255s don't seal up. Maybe some of you have some successful insight to this problem.

 

You are probably overthinking this. Even the cheapest intake gaskets will work as long as you have good surfaces on the heads and intakes. I have been using Mr.Gasket brand for years and have never had a leak.

 

To my understanding, the main cause of failure of the plastic vortec gaskets was due to the factory torque spec for the intake bolts being too much.
Supposedly GM updated the spec in the repair manual to reflect a lower torque spec.
Correct me if I'm wrong on that.


I agree that you may be over thinking your gasket selection... I've had a 4.3 that blew the original intake gasket(as far as I could tell) at around 200K miles, and when I bought my 97 C1500 at 255K I replaced the original intake gaskets(bought from original owner who had ALL service documents, it was never done) as a precautionary measure since I had to dig in to replace the injectors anyways. I just run what ever Fel-Pro gasket my situation calls for.

 

I have been using felpro 1255 for a decade never had an issue

 

the issue was failure due to over tightening of the original gaskets. in most cases the gasket crushed and allowed coolant leakage into the cylinders.

newer gaskets should have metal spacers around the bolt holes to prevent crush of the gasket. the torque specs are also much lower than for a standard SBC gasket.

just look for the metal spacers in the gaskets you get.

 

^^^ This ^^^

Rather than controlling gasket crush by way of bolt torque, this system (basically the same as on the LS motors for example) allows one to simply tighten the bolts to some/any reasonable torque against the spacers, which the height of the spacers then sets the amount that the gasket crushes independent of bolt torque. As long as the bolts are tight enough (don't allow themselves to back off) but not too tight (strip threads, snap bolts, etc.) the gasket will be equally happy.

 

What he said ^^^^^
This is what I went with: https://sdparts.com/i-21066287-victo...asket-set.html
No problems so far...

 

I plan to use 1255 with a gasket sealer(not RTV) Permatex High Tach. Gasket usually comes apart when you do pull the intake.

 

Ditto VortecZ. My 2 cents. I always use Edelbrock 7235. Never use GM 89017465. Edelbrock less expensive and thicker (.120 .vs. GM .060). No plastic like GM.
Use Gaskasinch on head to hold gasket in place (crazy name, great product). Then on intake gasket side use thin layer of RTV around water ports. Torque to spec and forget it. No leaks ever. Not so with GM.