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head; bolts or studs?


1 tuff z

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i will be putting my engine back together soon and am debating on whether to use the turbo bolts or an arp stud kit when i pop the head back on. any experience or thoughts on either? i am running a jcr blower kit on my z, stock compression turbo block w/p-90 head. running 6-8lbs boost.

 

thanks, david [1 tuff z]

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I had a terrible experience with head studs in my Buick V-6. Head studs, when screwed into a water jacket, acts like a wick if the threads do not have the proper sealant on them. Since the L6 came from the factory with head studs and I have never heard anyone report the same problem, then maybe it is not an issue with that engine. Just follow the product's procedure for thread sealant and torque specs.

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My L28 didn't have head studs icon_confused.gif . It had hex headed bolts. Expensive to replace them suckers. Probably cheaper/easier to get some ARP studs and nuts.

 

I don't think that the L28 has the head bolts passing thru any water jackets though, so it shouldn't cause any problems.

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Scottie,

 

So soon we forget...

 

L6s had head bolts for cost reasons. FYI... if your motor mounts are a bit worn and the engine is set back a bit, you can't get the head on/off with studs 'cuz the hoods latch mount gets in the way. Check for the same kind of problem with a V8 install.

 

Also, at least two of the L6 head bolts end in a water jacket. I know the left front does and I think the left rear also.

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What that means is that the bolt hole is open (or passes through) to one of the water jackets surrounding the cylinders. But I think I was mistaken when I posted that this occurs on the L6 head bolts. I looked at an L6 block in my garage and I can't see where that happens.

 

I do recall pulling head bolts and seeing water corrosion on the threads. I'm confused.

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  • 1 year later...

I would go with head studs. Head bolts can only be torqued down to 60-70 pounds, im sure nuts on studs can go a little more than that. Also, head studs make aligning the head gasket and head a HELL of a lot more easier, saving scratched head surface and/or a damaged head gasket during install.

 

cheers

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I got turbo headbolts, I think, they may just be regular ones, 23 psi with no problems.

 

I have also removed head bolts to replace/swap a cam and had water come up thru the bolt hole, although I don't have that problem with my current f54 blocks.

 

Geez Scottie, were you asleep at the wheel or what? :lol:

 

Head studs make it harder to remove the head. Leave them loose until you got the head on the block.

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New bolts are something like 45 bucks or so and a set of ARP studs are 125 or so.

 

In the ARP instructions it says to use less torque on the nuts then you would use on the bolts. Seems like it said 15% or so less torque. I thought it was odd but, did what it said. THe setup felt like it could take a ton of torque conpared to the bolts that felt like they might be having trouble when I was torqueing them down. :roll:

 

The bolts are certainly easier to work with though.

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Guest Al 260Z

Corrosion on stock head bolts is common. Replacement of corroded head bolts strongly advised (they'll break when you try to torque 'em and you'll have fun getting the busted end out - tell me about it!) I use the turbo head bolts on my N/A Z rebuilds. I'd consider studs for a race or turboed engine.

 

On none of the several L6 engines I've taken apart has any head bolt entered a coolant passageway.

 

I'm pretty sure the cause of the head bolt corrosion is the combination of coolant and combustion gasses that seap through/along the head gasket. Probably due to the higher thermal stresses on the intake/exhaust side of the head, the longer head bolts on this side seem to suffer more corrosion than on the spark plug side.

 

My head bolts get a thorough coat of anti-sieze for corrosion protection. So far this seems to help. With anti-sieze on the threads I torque to the lower end of the torque spec.

 

Later,

Al

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I'm running headstuds now since it was only $125 for a set. I was worry about water leakage as Scottie mentioned but I've have not had any problem with the studs on L6. I just got them torqued to 60ft/lb.

 

Only thing I had problem with was trying to get a 12 point 12mm deep socket. It was impossible to find a 1/2inch drive that fit on the cam tower side head studs. So ended up with 3/8 drive (I think that's the size) socket with an adapter.

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