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Here are a few thoughts:
1) You can convert to studs if you'd like. Make sure that they're at least grade 8
and have the correct thread length so that they don't bottom out in any holes and
leave any threads exposed above the top of the block deck. Use a drop of
"non-removable" thread locker on each stud. This will seal the threads in the
block and help prevent the studs from turning when you remove the nuts at some
later date. Threadlocker is especially recommended for any holes that go all the
way through into the water jacket.
Important Note: If you ARE going to use thread locking solution on the studs in
the block, it's very important to put some tension on the stud before the
threadlocker begins to set, which only takes a few seconds. Otherwise, there will
be a layer of hardened threadlocker solution that will be under compression
between the threads, and hardened threadlocker, while fairly stiff, is still a LOT
softer than metal and it will gradually compress to varying degrees, which has the
potential to cause the stud to loosen up. To avoid this, you want to install the
studs so that there is firm metal-to-metal contact between the threads when the
stud is under tension. Here's how to install the studs properly:
a) After cleaning up the threaded holes in the block (see 3 below), lay the
cylinder head on top of the block (with NO GASKET) and make sure that the holes
line up perfectly.
b) Put a drop of threadlocking solution on the threads of a stud (just on the
threads that screw into the block), slide it into one of the central-area cylinder
head holes, and screw it into the block until the non-threaded part of the shank
stops against the block surface. Don't try to screw the stud too tightly into the
block...just snug. If the threads are clean, screw the stud in finger-tight, then
snug it up with a pair of pliers against some leather wrapped around the top of
the stud.
c) Immediately (don't even wait five seconds) install a nut on the stud and
tighten it to about 20 to 30 foot pounds. Let it set for a few minutes.
d) Repeat steps b and c for each stud.
e) Make sure that there is still 20 or 30 foot pounds on each stud, and let it
cure fully for the time indicated on the threadlocker instructions. Overnight is
good.
f) Remove the nuts and the cylinder head, then install the gasket and finish the
head installation as usual.
This procedure may sound like overkill, but believe me, it's well worth it, since
the loss of tension on even a single stud can allow a head to warp and cause a
gasket to start leaking. (Note: Some people say that just screwing the studs
firmly into the block and allowing the unthreaded part of the shank to tighten
down against the top of the block surface is adequate to squeeze the Loctite, but
this is a bad assumption. First of all, it will damage the uppermost thread if the
stud is screwed too tightly into the block, and it will also create a stressed
area in the stud at that point.)
2) By the way, NOS head bolts should still be available. It seems that Vintage
Power Wagons had some last time I checked.
3) Before installing studs or head bolts, run a "chasing" tap (preferably not a
cutting tap) through the threaded holes in the block. This will clean out any crud
in the threads without removing any metal.
4) Check the top of the block for flatness. If the surface is more than a few
thousandths out of true, it may require resurfacing. A small amount is tolerable.
Usually, the head will tend to warp more than the block, but it could involve both
items. Make sure that you check lengthwise across each thin web area between the
cylinders, as this is where gaskets usually fail.
5) Check the head for flatness and have it resurfaced if necessary. This service
does not cost very much.
6) I suggest using Permatex spray-on copper-impregnated gasket cement. An extra
coat on each side of the gasket won't hurt.
7) Naturally, torque and cross-tighten the bolts/studs per specs.
Have fun,
Alan
Lisa wrote:
> *This message was transferred with a trial version of CommuniGate(tm) Pro*
> Barry removed the head from his M37 this weekend.The block,
> pistons, cyl walls, and valves look good, so he de-carboned
> them. The head gasket showed carbon leakage between cyls 5 &
> 6, and the seller did tell us there was a problem there. I
> spent time experimenting with various colors of Arvoe in the
> spray can. Looks like M.C. Green is the color for his M37.
> Today I went to wire wheel his head bolts and discovered
> many were unservicable due to corrosion. My questions are:
> 1) Can we convert to studs in the block, and 2) Should the
> top surface where the head bolts make contact be surfaced so
> that is is even and paralell to the head surface, or 3)
> Should he buy a new head and head bolts? Also, is there any
> way to prevent this corrosion, or were the previous owners
> negligent about antifreeze and flushing/replacing coolant
> regularly?
> Thanks all,
> Lisa
This archive was generated by hypermail 2b29 : Tue Apr 04 2000 - 21:57:07 PDT