HARRISONMIRAGE

GM HAS A LIQUID TEFLON SEALANT FOR HEAD BOLTS.IVE USED IT ON BIG BLOCK 454'S WHERE THE HEAD BOLT HOLES GO INTO THE COOLANT PASSAGES WITH NO PROBLEMS.I THINK ANY OF THE SUGGESTED SEALANTS WILL WORK.I HAVE LEANED TOWARDS THE TEFLON BECAUSE I FIGURED IT WOULD GIVE A MORE EVEN TORQUE DUE TO THE FRICTION QUALITYS

turbo2256

Tried the teflon stuff Loctite s, ARP s and got nothing but leakage looked like the threads were to tight to let it in between. Ended up using Locktite 262 I believe at the time didnt have much choice but hasnt leaked since.

excaleagle42

dave, some of the bolts go directly into the water jackets that cool the cylinders. they need sealant or water can leak pat the bolts and get in your oil. it is a good idea to use it on all the bolts for even torque readings. be sure to run a tap through all the holes first to clean out any sealant left in the block.
this is my preferance, bolts are fine but i like studs better with permatex liquid teflon thread sealer. if you ever retorque the heads, you won't disturb the sealant using studs. it is overkill but also cheap insurance to me.

Dave Schumacher

Thanks for all the replies. I think I'll just use the permatex. I am an engineer and can tell you guys from past torque testing exp. that the teflon sealers will increase the the preload (strech) on the bolt at the same torque, possibly to the point where the bolt could fail.

blue thunder

That what I was thinking Dave. This is why suggested torque values are changed for different thread materials. Teflon has a very low coefficient of friction and will give a higher effective clamping force. If the yield strength of the bolt is exceeded trouble will be close behind.

BT

excaleagle42

that is too much tecnical mumbo jumbo for me, but if you use teflon to seal studs, the clamping force won't change because you use oil on the threads by the valve springs. the threads coated with teflon in the block don't turn while torquing.

BLOWN 1100

Most of the engine builders i know use
Indian Head sealer, it has been around
about 40 yrs. It can be bought at Auto Zone
Loy