Hey All, The bottom 5 head bolts seems to go into the water jacket. What's the best way to seal them off? I've heard mixed things about what should be used.
1975 302? All those bolts should go into a blind hole. Sometime later (5.0 blocks?) there were bolts that went into the coolant, and then just a good coating of thread sealer with Teflon on the threads should do it. But the 289 and early 302 blocks had dry head bolts. Just lube the threads with oil or use an assembly moly like the ARP lube. BTW - back in the day we would just use black RTV for head bolts that went into the water jacket. But they make special products now that work so much better, so why not use that when needed.
Bottom holes went into the coolant gallery starting with the 1980 E0AE blocks. If that's what you have, ordinary pipe thread sealer will do, you can buy it at any hardware store.
Loctite 592, or 567 is what I use, just depends on what the store has at the time. Never had an issue using sealant that wasn't rated for high temps.
If std sealant fails, engine was badly overheated. At that point a little seepage would not be a worry.