cylinder head bolts

[jveik]

i am wondering if any of the cylinder head bolt holes in the block for small block chevys protrude into water jackets.

[maxwedge]

If you look down into the hole you can see where they end, if the bottom is open they are usually in a water jacket.

[luxeryvic]

yeah, they do

[randy78]

they do

and use a non hardening lube sealer such as plumbing pipe thread sealant on the threads and engine oil on the head seats

and chase clean the bolt hole threads

so they will torque properly

good luck

[silicon212]

If I use sealant (which I generally don't), it's Permatex #2 Form-a-Gasket. It's what the factory used.

I personally feel that sealant will give you a bogus number on your torque wrench and the incidence of leakage due to no sealant is almost nonexistant.

Case in point is the 350 in the car in my sig. This engine now has 300k miles on it since I rebuilt it in the summer of '93, and I had the passenger head off a month ago to replace a bent valve. Inspection of the bolts revealed no leakage or corrosion.

[maxwedge]

Areed an the sealant/torque issue, I use some lite non -hardening thread sealer and add about 5 lb/ft to the torque settings.

[jveik]

so basically, if i wanted to be on the safe side, i could use some sealant and just up the anty on the torque wrench a little bit. or i could just as well not use sealant at all and more than likely nothing bad would happen?

[maxwedge]

Your call.

[MrPbody]

DANGER WILL ROBINSON!!!

Absolutely use a sealant. Permatex "Aviation" or "Super 300" are the two of choice. You MUST use some sort of lubricant on the bolts to get an accurate torque reading. Both of these sealants provide a similar result as motor oil, which is used on engines with "blind" holes. ALL the head bolts go through to water in a factory production small block (and big block, for that matter).

I too, have seen engines without sealant that didn't leak through. But I've seen 100 that did for every one that didn't. Chevrolet says to use a sealant. When all else fails, follow intructions! Chevy used #2 in olden times. They used Teflon (Slick-Tight) the last 20 or so years of production.

Sorry to sound like a smart-ass, but this is an important issue regarding the longevity of a Chevy engine, and witch-doctor cures and home remedies don't make it. Do it right, do it once!

Jim

[jveik]

how do the sealants change the torque reading? Well, i know "how" they do it but i mean do they make the required torque reading on the wrench go up or go down to get the correct torque? i was going to just use motor oil or petroleum jelly, but i think i might opt for one of the sealants you listed above. are both of these sealants ok for aluminum heads, i have no idea if there are products out there that will be fine for iron but eat away at aluminum

[Will Help]

This design is one little thought of reason why GM and other manufacturers have trouble with blown head gaskets.

Not having head bolt bosses that go all the way down to the lower crankcase allows the head decks to flex as they heat and cool. This flexing/bulging, combined with the pressures of combustion, breaks the gasket bond over a period of time. Kind of like putting hot water in a milk bottle and putting the lid on. The bottle will start to bulge as pressure increases. Put the same bottle in cold water and it will pull its flat surfaces in. Having the bolts go all the way to the bottom end stabilizes the head deck and keeps flexing down to a minimum.

Also little known problem is aluminum heads on cast iron blocks. Aluminum expands and contracts almost twice as far as cast iron when it heats and cools. This also breaks the gasket bonds faster.

[Blue Bowtie]

I've got a pretty good handful of SBCs, and I don't have any problems with head gasket failure. I've replaced quite a few on other engines, but the five bolt design of the old SBCs made it one of the strongest head/deck joints of all the major manufacturers.

If you want good sealing and no torque errors, try one of these:

[MrPbody]

The types listed by Blue Bowtie are just fine. We use Permatex Aviation becasue we use it for several other sealant applications as well. We have no head gasket issues, either. The "torque issue" is more a "dry" hole vs. a "lubed" hole.

The "open" holes to water are pretty much exclusive to Chevys in the GM line. Buick, Olds and Pontiac V8s have "blind" holes and separate bosses. Even though they only have 10 bolts, they suffer fewer gasket problems than the Chevys.

Small Fords have open holes in some blocks, blind in others. The big Fords are blind holes. Again, 10 bolts, few problems. Big Dodges have 17 bolts like the SBC, and they're open. We've seen SOME problems, but not like the SBCs. The small Dodges have 10 blind holes.

NOTE: Most of the "blind hole" types have larger diameter bolts, too (1/2" vs. 7/16"). The Lima (385 Series) Fords (429/460) have 9/16" bolts.

Just for clarity.

Jim