several folks here are talking about using anti-seize on aluminum heads - DON'T DO IT!!!!!!

The torque spec on the intake is 26ft-lbs, into aluminum. Adding anti-seize will increase the torque, by reducing friction, by as much as 50%. So that 26ft-lbs becomes 39ft-lbs at the thread.

This can lead to thread damage on the heads. These threads are not that stout... remember, aluminum is not iron.

These bolts are not so tight, and being exposed to oil from the inside, will not seize... I have NEVER had a bolt not come out of an intake. Just be sure the engine is cool and all metals are at their static stat (temp wise), and they will come right out. A breaker bar will also help.

This is no different that installing plugs, but the difference is the torque and heat are much different. If you overtighten plugs, we all talk about loss of thread, this is not exclusive to the plugs!!! This can happen on the heads at the intake.

Another reality, we cannot get a torque wrench in and properly torque the plugs, so for the most part, we are hand tightening... turn till it stops, half turn more. That's fine, and anti-seize is ok here... but not on a bolt that is this highly torqued.

Lani - Congrats on a job well done!!!!

 

I suppose one could just remove the bolts and pull it forward.

I have an **** tendency to follow the procedures determined by GM for this vehicle. It was just much easier for me I think having everything out of the way. Bogus is always on me about disconnecting the neg batt cable, many of the procedures always say disconnect neg batt cable so I do. Some people prefer not to on many of these procedures.

I've noticed the engine seems to be running smoother, not a performance related issue so much but there may be a benefit there no sure. I'm thinking the old gaskets were leaking some, but now it's all sealed up tight.

 

Thanks but after this notation you may need to take that back!

I used a little anti-seize on the thread area where there appeared to be anti-seize from the factory. When I cleaned the bolts, each one had a elastic substance about 1/4" from the tip of the bolt up about 1/2" then the remaining portion to the head was clean. So I applied a little in the same area. I torqued them to 8Nm in sequence then to 48Nm in sequence. I did note that the rear two bolts #10 and #11 were not very tight, as it took nothing to break them free but most of the others required a little pressure.

So now what should I do, in a week or so re-check the torque? Should I increase it to some other value?

Not sure if you were quoting specs but my 93 service manual calls for 48Nm (35 lb-ft) on the final pass.

 

I would not go over them. The "elastic" substance was simply grey RTV,NOT anti-seize! Anti-seize will not become elastic.

The best bet is RTV, if anything, to lower the chance of oil weaping up the bolt threads (there is some pressure inside the motor) but it's slim.

Much of the paranoia revolving around intake manifold gaskets is a result of the L98s junk system... a wet intake... multiple leak points, you name it. The L98 requires much of these tricks, or else leaks WILL start to spew forth... the LT1 has none of these concerns... and to top it off? The LT1 heads have pin holes machined into them so the intake gaskets will fit EXACTLY where they are supposed to fit, and not slide about once one puts the manifold on.

When I do an L98 intake, I hit both sides of the intake gasket with spray on Copper Gasket Spray. This will allow a better seal between the intake and the heads, and provides a touch of tackiness to allow the gaskets to not shift as much. Another trick is to tape the gaskets to the heads a little (there is a spot in the middle of the head that works great for this).

 

I find this extremely hard to believe! 10lbs additional unwanted torque due to using anti-sieze? I'm sticking with the time honored dis-simuler metal theory and using the stuff....too many Holly carbs stripped due to not using anti-seize on the bolts....

"one man's fancy is another man's folly"

 

I have read elswhere about not using anti-sieze due to it changing the torque applied and lets the bolts loosen.This applies mostly to mid to high torque ranges.I agree with Bogus.

 

Ok I won't mess with them and hope things are ok. But I actually did meet you half way on the thread lub issue, I put a tiny bit of RTV on the last two threads near the head, so they had a little anti-seize and a spot of RTV.

What Andy is referring to above is the difference between wet torque and dry torque. Any time a fastener has some form of lubricant it's considered a wet torque. And that means an increased torque value.

So many times the service manual doesn't go into details about these theories. They just say install the bolts and torque to xxx. It's rare they mention a form of thread lubricant. Why I'm guessing two possible cases; one it is truly not needed or it's a process of basic mechanics and it's not necessary to mention it. Problem is they don't say wet or dry torque.

Yeah those pins were nice, although one of the old one's stuck in the hole and I had to touch it with a tiny drill bit to pull it out. But yeah they made that process much easier.

So perhaps I did ok with dry gaskets, a fairly decent job on the sealant (let's hope) and goofed on the anti-seize of the bolts and perhaps have a slightly under wet torque manifold.

But so far no leaks and she runs really smooth.




Here's a couple pics:

 

You have forced me to dig out my "Pocket Reference," by Thomas J. Glover, Second Edition, page 272.

This is a table of info:

5/16" x 18 thread/torque rating

Lubricant:
No lube, steel ---------- 29ft lbs.
Plated and cleaned ---- 19 (34%)
SAE 20 wt ------------- 18 (38%)
SAE 40 wt ------------- 17 (41%)
Plated and SAE 30wt --- 16 (45%)
White Grease ---------- 16 (45%)
Dry Moly Film ---------- 14 (52%)
Graphite and Oil ------- 13 (55%)

As you can see, the lubricants have a serious impact on torque requirements. I was not kidding.

Helm does not mention it cause the makers don't care to test for it. They test for dry torque, and that's what really matters...

Once you start lubing a bolt, all bets are off.

 

So what are the possible consequences of using anti-seize on these bolts and torqueing them to 48Nm?

Certainly I should remove them, clean and re-install them should I? I would think the hole now has lub in it and it would have to be completely cleaned out to do a dry torque.

This is all your fault (LOL) didn't have that tech note ready!!! <Grin>

Hey ya'll Happy New Year!

 

yea, well... I was gonna suggest it...

I don't see a reason to mess with it. The job is done... leave it be.

 

Question: Do the above numbers represent additional torque to the 29ft lb setting, or actual torque reduction due to the lube factor???

ARGHH. OK, so what this gentleman is saying is that if I juice up a steel bolt with "Graphite and Oil", then set my torque wrench setting to 29ft lbs, the "actual" resultant will be 13ft lbs. (55% less than my intended 29ft lb torque).

Before your stated:

The torque spec on the intake is 26ft-lbs, into aluminum. Adding anti-seize will increase the torque, by reducing friction, by as much as 50%. So that 26ft-lbs becomes 39ft-lbs at the thread.

He says Tomaaaato and you say Tomato.....

But it has been a year since I did my intake, using anti-seize with no problems. I will however, take heed of the information you provided, and will re-torque my intake bolts this weekend. Kudos to you for digging out your cheat sheet and presenting these numbers!!

 

no, the chart is missleading, but what it is saying is to get the same thread torque at 29 ft-lbs dry, would require only 13 ft-lbs of effort.

So, if you were to put 13 ft-lbs on that bolt, it would actually be 29 at the threads. That is what lubrication does. It reduces the effort on the tightening. It's called "friction." And oil reduces friction. Whether it's shearing or torque or whatnot, it's all friction and oil reduces it.

And anti-seize is one of the slickery lubes out there...

 

'slickery' is that a word???

Hey so what I was repeating was incorrect, if it's wet torque it would be less torque applied to reach the dry torque value.

Oh great so now I have slickery over-torqued bolts.

Alright I won't worry about it, but next time...

HNY

 

Well, judging from your photos, I think you have done an excellent job! You really scrubbed that old RTV off nicely!!! Awesome!! Whatever you do, in a fit of this Torque confusion debate: don't loosen the intake bolts to relieve a theoretical wet/slickery/lubed/ over-torqued condition....as this action may release enough compression on your front and rear RTV seal to allow for another leak. Leave well enough alone...I am highly confident that your heads are not in jeopardy of stripping...Good forthought in replacing your injector O-rings too!!

 

Actually the old RTV just peeling free almost in one continuous piece. The forward rail edge pulled free about 90% and the aft rail edge was in three pieces. A few specs of residual was there but it can off by just scratching it with my thumb nail. I covered the intake ports and stuffed a bunch of shop towels in the valley then cleaned everything in site using throttle body cleaner and lots of towels. I rewiped each mating surface several times with a fresh clean towel just before assembly.

You can see in the one photo, where the front intake ports were a nice golden color but aft two ports have a spray pattern of carbon. That's why I think the gaskets were leaking a little too. Which I now attribute to the engine running so smoothly compared to before.

Yeah on all the old o-rings on the end when goes into the intake they had flatten a little the new one's an upgrade by GM from the black to the blue one's. The instructions that came with them mentioned about these replacing the older style. Someone mentioned it in my prep up to the procedure. But yes I was glad I picked those up too and did that maintenance.

Each time I do one of these indepth procedures, I realize why I do the work myself. One I know exactly what was done and how it is done. Secondly, with all the other parts that have to be removed, whether there are new components or aging components, most shop mechanics aren't as careful as I am. You know how typical it is to break something while fixing something else. And shops don't volunteer to tell you oh we broke some connectors in the process and just pushed them back on. You discover those things after the fact. Most of these C4's are aging and you have to be careful taking things apart. Plus shops don't take the precautions to protect the other parts of the vehicle. I hate it when you pick you vehicle up from the shop and there are greasy hand prints or grease on your carpet. They don't care it's not their vehicle. So that's one reason I prefer to do the work myself.