kbuhagiar

Hello Folks

I pulled the valve covers on my 1986 Corvette 350 TPI engine (installed in my 47 Plymouth) in search of a valve train noise.

The engine was rebuilt by the previous owner 2000 miles and 2 years ago. Upon initial inspection I find that the heads had been upgraded with screw-in rocker arm studs.

One of the studs had backed out, causing the noise. Easy fix, right?

While further inspecting the passenger side head, I discover a small amount of what appears to be anti-freeze puddled in the back of the head.

Now, I know that this coolant was not introduced into the head - it was there when I pulled the valve cover. The engine was running fine and not overheating or exhibiting any properties that would indicate a breach of the water jacket (i.e. cracked head). There is no indication of oil in the radiator, either.

Could this be caused by improperly sealed head bolts? Or perhaps the screw-in studs go through to the water jacket (or the intake port)?

If so, what kind of thread locker or sealer should I use on the head bolts & rocker studs?

Thanks in advance!

Aardwolf

The rocker holes are blind (use thread locker!). For thread sealant I have found ARP to be the best. Over the years and several engines that I've built and torn down, I've tried a variety of different products (RTV, teflon, etc). The ARP thread sealant has consistently stayed on the threads better.

bwiencek

A little bit of water can come from head bolts that were not sealed properly and you really should take care of it ASAP as water in the oil can cause you to wipe bearings real quick.

If you're careful (and a little lucky) then you may be able to drain the coolant below the head level, pull the bolts one at a time, clean them up and then use your favorite thread sealer (ARP or I've had good luck with the teflon thread sealer paste that the parts store sells too) and re-torque the bolt down.

If it's just a tiny bit then do what I used to have to do occasionally for circle track engines that wouldn't seal with head studs - run about 1/4 dose of stop-leak in the cooling system (follow directions - some need water only) and then run it until the leaks stop - (learned that trick from a big name engine builder )

coupeguy2001

First, if you drain coolant from the block, use the drain holes right above the oil pan rail.
second, If you have water in the oil, and it runs fine, tighten all the intake bolts.
Third, Jumping to conclusions about the headbolts may lead you down the wrong path.
You can have a cracked intake, bad intake gaskets, bad head gasket, cracked head, etc.
If you have the aluminum 128 heads, the heads can crck in the middle head bolt hole and leak coolant through the crack to the oil area.
be sure to thoroughly investigate, and not quit looking for the coolant path too soon.
The minute the weather goes from too hot to too cold, and too cold to too hot, the leak path gets coolant through.

C4happy

My 113 heads have a crack on that middle head bolt as well I just put some gasket maker Silicone under the head bolt washer area

ch@0s

While were talking about heads. I don't remember if my old heads had washers on the bolts. The new Gm bolts I have did not come with washers. Do i need to get some? I have aluminum GMPP Fast Burn Heads.
Sorry OP, I'm not trying to hijack.

kbuhagiar

After much review I have decided to:

Drain the cooling system
Remove all of the rocker arms
Remove all of the screw-in rocker arm studs
Remove head bolts, one at a time, clean, re-seal and torque to specs
Seal/thread-lock and replace all screw-in rocker studs
Replace and adjust all rocker arms
Change oil and filter
Cross my fingers.

Questions:
(1) What would be the torque specs for the (shoulder-less)screw-in studs?
(2) What is the best sealer to use on the head bolts?
(3) Is there a compound sealer/thread locker I can use on the rocker studs? My research so far indicates that the rocker stud holes go straight through to the water jacket or intake port, depending on location.

Thanks again in advance.

coupeguy2001

alumnum heads ALWAYS need washers under the head bolts' heads

kbuhagiar

I have searched high and low and still cannot find the answer to the following:

What is the torque spec for the (shoulder-less) replacement screw-in studs? The heads are cast iron.

These are not the factory-style studs, so the 50lb torque spec that GM recommends for "shouldered" studs does not apply.

Thanks again.

ch@0s

Thanks that's what I though. I ordered GM bolts #12495499.

I called Summit and asked them why they were offered for Aluminum head vehicles. They said thy will work but they recommend I add washers.
Aren't the Performer RPM heads aluminum? I will be ordering the washers they recommend they are only $14. Thanks for your help.

Make
CHEVROLETEngine Type
V8Liter
5.7CID
350Engine Size
5.7L/350Beginning Year
Chevy small block Gen I Cylinder Head Style (application)
Edelbrock Performer RPM

kbuhagiar

and yet, somehow, you did...

bwiencek

The only way the fastener will get resistance in order to apply a torque is when it bottoms out against the blind hole - IF I recall you don't torque those non-shouldered studs down - you simply install them snug with locktite to keep it from backing out and then install the rocker and adjust the lash.

I prefer shouldered studs as they tend to be stronger/stiffer and if the head is off the machine work to flatten the boss is pretty trivial...

kbuhagiar

Thank you.

The rocker arm bosses are not blind holes, they are drilled through to either the water jacket or the intake port, so they will not bottom out. However, the studs have a slightly raised surface at the top of the threads to limit how far it penetrates the boss.


So do I, but this is the hand I was dealt; the current situation (one of the threaded studs backed out, causing a rocker clatter) does not warrant head removal, which is fortunate as I don't have the time or resources right now.

94vettelover2

I would retorque the heads bolts down alittle more than stock(example-spec is 60ft-lbs,I would do 64ft-lbs).The head gaskets are crushed & loosening the head bolts is not a good idea(only made to crush once) but tightening alittle more than stock spec will crush the gaskets a hair more.This is what I would do.Actually if I were you & am questioning my work I would do it over again for peace of mind & doing everything perfectly.It won't cost much for parts(new headgaskets), but will be time consuming.Maybe do alittle porting as well for some extra power

kbuhagiar

I appreciate the comments.

The work in question was done by a previous owner. If it was my work I would have no doubts at all.
I will probably end up changing out the top end (heads and intake) sometime next year.
Right now I simply do not have the time to devote to a full-scale project, and I cannot afford to have the vehicle immobile until early next year.