Should head bolts be lubricated before they're installed? I get some "grabbing" when I tighten them and I'm thinking this can throw my torque readings off. On the other hand, will the presence of lube keep hem from holding their best?

What do you engine builders say?

Don't you have to seal up the the threads of the head bolts because they thread into the coolant passages (V6 Fiero)?

J.

Chase the threads in the block with a proper size tap. Do not use lubrication on head bolts when installing them! This will cause your torque readings to be way off. I have never lubricated head bolts when installing them. If the head bolts thread into coolant passages in the block it is a good idea to us a high quality sealant on the end and the last couple of threads on the bolts. That's my 2 cents, anyway.

[This message has been edited by Sidecar 2M6 SE (edited 11-19-2009).]

I always use permatex non hardening,(in the jar) it lubes the threads so they are not "catching" giving false readings & when it sets up, the thing is leak proofed.

While Sidecar 2M6 SE isn't correct in this particular application, he is right for most applications where torque is specified. Unless otherwise specifically mentioned, torque values for bolts and nuts are always for dry installation. Any lubricant will affect the final torque considerably (I believe up to 25%) if it was intended to be installed dry. However, straight from the 1986 Fiero service manual page 6A2-17:

"Coat cylinder head bolt threads with GM 1052080 Sealer, or equivalent, and install bolts. Tighten bolts in sequence - 90 N.m (66 lbft)"

GM 1052080 (which is still circulating on the net) is a teflon pipe sealant that has been replaced by p/n 12346004. This is the GM white goop used to seal the bolts that go through the water jacket. It costs about $20 a tube at the dealership.

Corky Bells book “Maximum Boost” states the following on lubricating the head bolts:

“If Molly Sulfide lube is used reduce torque measurement by 10% if regular machine oil is used reduce by 5%. Lubricating these surfaces is of such importance that if missed the engine must come back apart to apply it.”

Sidecar is right clean those threads with a new sharp tap if nothing else.

quote Originally posted by Bloozberry: While Sidecar 2M6 SE isn't correct in this particular application, he is right for most applications where torque is specified. Unless otherwise specifically mentioned, torque values for bolts and nuts are always for dry installation. Any lubricant will affect the final torque considerably (I believe up to 25%) if it was intended to be installed dry. However, straight from the 1986 Fiero service manual page 6A2-17: "Coat cylinder head bolt threads with GM 1052080 Sealer, or equivalent, and install bolts. Tighten bolts in sequence - 90 N.m (66 lbft)" GM 1052080 (which is still circulating on the net) is a teflon pipe sealant that has been replaced by p/n 12346004. This is the GM white goop used to seal the bolts that go through the water jacket. It costs about $20 a tube at the dealership.

Ok Bloozberry, so just where was I incorrect?

I have used Permatex Ultra Black sealant on head bolts for years with no problems what so ever. I coat only last few threads so that the sealant doesn't cause the torques readings to be affected too much. I have built/rebuilt several engines over the years and I have never had a coolant leak due to head bolts not sealing properly in the holes that end in the coolant passages. If you use too much sealant on the head bolts it may affect the torque readings. I know this from experience. Perhaps the GM sealant will not cause this. I am not sure as I have never used the GM sealant but if it has Teflon in it, I bet that it will. 20 bucks is too much money for a tube of sealant for head bolts as far as I am concerned.

quote Originally posted by Sidecar 2M6 SE: If you use too much sealant on the head bolts it may affect the torque readings ... If [the GM sealant] has Teflon in it, I bet that it will.

The GM torque specification assumes that you are following their entire published procedure, which includes "coating" the threads with sealant. If the threads were to be assembled dry, the specified torque values would probably be higher.

quote Originally posted by Sidecar 2M6 SE: Ok Bloozberry, so just where was I incorrect?

Perhaps we mean the same thing Sidecar, but have different understandings of the word lubricant. According to my interpretation, anything other than bone dry is a lubricant, that includes thread sealers, oil, wax, anti-seize, etc. Re-reading your first post, I now believe you meant not to lubricate the threads with oil, which IS correct. Technically however, adding sealer to the threads is not the same as torquing them dry. The sealer acts as a lubricant since there is no way to prevent the sealer from staying on just the bottom threads of the bolt. As you turn it in, the sealer coats all of the threads and acts as a lubricant too. As Marvin points out, if the sealant wasn't specified by GM, then you would expect the torque values to have been lower for the head bolts.

quote Originally posted by Marvin McInnis: The GM torque specification assumes that you are following their entire published procedure, which includes "coating" the threads with sealant. If the threads were to be assembled dry, the specified torque values would probably be higher.

Page 6A2-24 of the 1985 Fiero Service Manual from GM indicates that the head bolts for the 2.8 can be torqued anywhere between 65 - 75 foot pounds.
Page 6A2-24 of the 1986 Fiero Service Manual from GM indicates that the head bolts for the 2.8 can be torqued anywhere between 65 - 90 foot pounds.

These are very wide ranges for torque. The other important point to mention is that a torque wrench requires calibration at least once a year. I worked for Snap-on in the national repair center here in Canada for many years and one of my tasks when I worked there was to calibrate customer's torque wrenches. Proper calibration of your torque wrench is very important.

New head bolts usually come with a dry sealant already applied to the threads. Experience has taught me that using an oil based lubricant on bolts that are to be torqued is usually not a good idea. If the threads are catching enough to affect the final torque setting on a head bolt then that is a very big catch on the threads and they should be chased with a tap before final assembly.

Bloozberry, to me a sealant is a sealant and a lubricant is a lubricant, . I agree that the use of a sealant may cause a difference in the torque readings but I don't believe that it would cause as much of a difference that a lubricant would.

These are just head bolts, this is not rocket science.

[This message has been edited by Sidecar 2M6 SE (edited 11-20-2009).]

Actually you are both wrong. All published torque specs are wet, not dry. It's been that way for oh, 20 or 30 years.
Why? because dry torque is not reliable due to dirt and remnants in the threads.

consider what both of you said, the head bolts are torqued dry, but the ones going into the coolant jacket are torqued wet (due to the sealant). You see something worng with this? you should.
Dry torque tends to be much higher due to the friction causing false indications whereas wet allows for the lubricant to help keep the particualtes in a semi suspension and not clogging the threads.
This whole issue of dry vs wet has lead to measuring the stretch on the bold, a better indication of the clamping force actually exerted by the bolt.
For this motor, all torque specs are WET. (and that does not mean dripping with oil either, it is a simple thin coat of light oil)

PS, for the original question, the trheads in the head and on the bolt should be clean and free from dirt and such. Chasing the head threads with a tap is a good idea, as well as a thorough cleaning of the bolts before lubing or applyin a thin sealant coat.

[This message has been edited by tjm4fun (edited 11-20-2009).]

quote Originally posted by tjm4fun: Actually you are both wrong. All published torque specs are wet, not dry. It's been that way for oh, 20 or 30 years. Why? because dry torque is not reliable due to dirt and remnants in the threads. consider what both of you said, the head bolts are torqued dry, but the ones going into the coolant jacket are torqued wet (due to the sealant). You see something worng with this? you should. Dry torque tends to be much higher due to the friction causing false indications whereas wet allows for the lubricant to help keep the particualtes in a semi suspension and not clogging the threads. This whole issue of dry vs wet has lead to measuring the stretch on the bold, a better indication of the clamping force actually exerted by the bolt. For this motor, all torque specs are WET. (and that does not mean dripping with oil either, it is a simple thin coat of light oil) PS, for the original question, the trheads in the head and on the bolt should be clean and free from dirt and such. Chasing the head threads with a tap is a good idea, as well as a thorough cleaning of the bolts before lubing or applyin a thin sealant coat.

Yes, tjm4fun you are right! I just found the following on page 5-30 of my 85 service manual. Funny thing, this is in the brakes section, go figure.

(Use a reliable torque wrench to tighten the parts listed to insure proper tightness without straining or distorting parts. These specifications are for clean and lightly lubricated threads only; dry or dirty threads increased friction which prevents accurate measurement of tightness.)

Cheers,
Stu

[This message has been edited by Sidecar 2M6 SE (edited 11-20-2009).]

quote Originally posted by tjm4fun: Actually you are both wrong. consider what both of you said, the head bolts are torqued dry, but the ones going into the coolant jacket are torqued wet (due to the sealant). You see something worng with this? you should.

OK, so it's my turn... just where was I incorrect? The Engineer's Handbook, which is a standard referenced across all of North America by professional engineers, contains a reference table for standard steel bolt torque specifications that cross references bolt diameters, thread coarseness, and SAE grade, to standard DRY torque in foot pounds for fasteners threaded into steel or cast iron. These are the standard torque values applied to fasteners to achieve the correct clamping force intended by design engineers within the limitations of the bolt's capabilities. They are also the standard values to be used when torquing any bolt unless otherwise specified differently in an engineering design. In Pontiac's case, they did exactly that in their service manual... and that is exactly what I said in earlier posts. I quoted the service manual directly which says to coat all the head bolts with a sealant. A sealant is not considered to be a dry application, and so GM's torque specs are to be used. Try re-reading all the posts in this thread, and please, if you could identify the source of your statement that it has been 20 or 30 years that standard torque specifications are now with a lightly lubricated bolt, it would help me to update my source of references.

You did not account for thread sealant which is NOT used on all the bolts, it is only used an then end 4 bolts, not a minor discrepency. if you find older service manuals, and in the 70's auto courses, it is clearly stated that torque specs as published are all wet. you were less wrong, but I wanted to make a point. in any service manual, it is wet torque.
Honestly I doubt you will find any online ref to that, but I have seen it in print, and will see if I still have older service manuals that state that.
I mean no offense to you (or anyone), I just want to see things done correctly. no one here (with the possible exception of Will) is assembling a motor in a operating room, and we have to live with what is stated in the manuals. the unfortunate part is that the manuals are written with the understanding that they are talking about wet torque, as nothing in a service environment is dry.
I will attempt to find an online ref when I have some time also.
I am basing this on assembling motors for over 30 years with no assembly failures. As with anything online, you can take that with any grain of salt, but if you search on any of my history with car forums, you will see I don't speak out of experience and knowledge.
In reality as an engineer, I understand all too well that published engineering specs are not a bible, but a reference to be used with consideration of the final use. that is a not negligible factor that is only learned with experience. and if you don't get what I am infering is that design and theory often fall apart in the presence of reality.

[This message has been edited by tjm4fun (edited 11-21-2009).]

I have always lubed my clean headbolts with a very light oil, and torqued them to the maximum spec. I'm now 60, and haven't lost one yet.

My 2 cents.

Go to www.arp-bolts.com and read their explanation about head bolts and lube.

i own a machine shop and all torque values for engines are based on wet.

The data below is abstracted from Machinery's Handbook, 27^th edition.

Normalized torque required to obtain the same preload in steel bolts in the size range from 1/4 to 1 inch diameter for different thread conditions (all threads are assumed to be dry except where noted):

Plain steel (K=0.2):                      100%
Non-plated black oxide (K=0.3):  150%
Zinc-plated (K=0.2):                    100%
Lubricated (K=0.18):                     90%
Cadmium-plated (K=0.16):            80%

Personal comments:

I agree that lubricated threads usually produce more consistent results than dry threads when torque is the only means of setting fastener preload. I use anti-seize compound on almost all threaded fasteners (e.g. bolts, screws, and studs) unless there is a compelling reason not to, and I usually use a torque value slightly (~10%) below the maximum specified in the FSM (factory service manual). Anti-seize is not intended as a lubricant, although it does provide some lubrication, and I've never had a properly-torqued fastener loosen, even with the anti-seize. YMMV. When a range of torque values is specified in the FSM, a good strategy would be to use the upper value for dry threads and tend toward the lower value for lubricated threads. If in doubt, always understand and follow the entire procedure specified in the FSM.

Finally, if fastener preload is really that critical there are three methods that produce better results than torque alone:

1) Use a strain gage embedded in or applied to the fastener to directly measure actual preload stress. This method is often used by GM and other manufacturers to establish the FSM torque values in the first place. It's very effective when nothing else will suffice, but it's not practical for production automotive applications.

2) If the fastener (typically a bolt or stud) is accessible both before and after tightening, you can use a micrometer to measure the fastener's actual stretch due to preload. Then you can either calculate the preload value or look it up in a reference table. This used to be the preferred method of determining connecting-rod bolt preload, but it usually can't be used with head bolts, for example.

3) If only one end of the fastener is conveniently accessible, the FSM will often specify a torque value plus some additional tightening angle ... typically from 90 to 270 degrees. The torque value is chosen high enough that it will take up virtually all the slop and clearances in the loose assembly (including initial gasket crush), and then the additional angle-specified tightening assures a more accurate and uniform fastener preload.

[This message has been edited by Marvin McInnis (edited 11-23-2009).]

quote Originally posted by mera7: i own a machine shop and all torque values for engines are based on wet.

What is the name of this machine shop? Location? Is this the 8000 square foot shop you have?

Rodney

When I read the thread I immediately thought of this segment I saw on PowerBlock a few weeks ago. I'm not saying it's a solid scientific study or that the factory service manual is wrong, but I still found it very interesting.

http://www.youtube.com/watch?v=6-XXVk_vwKw

EDIT: I guess the video embedding code that youtube gives doesn't work here, so I replaced with with a link

[This message has been edited by Toaster_Man (edited 02-07-2011).]

quote Originally posted by Rodney: What is the name of this machine shop? Location? Is this the 8000 square foot shop you have? Rodney

IBTC!

quote Originally posted by Toaster_Man: When I read the thread I immediately thought of this segment I saw on PowerBlock a few weeks ago. I'm not saying it's a solid scientific study or that the factory service manual is wrong, but I still found it very interesting. http://www.youtube.com/watch?v=6-XXVk_vwKw EDIT: I guess the video embedding code that youtube gives doesn't work here, so I replaced with with a link

Thanks for the link. Pretty interesting.

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Turbo 3800 E85 5spd spec5
11.53@126.7

Which engine? Year?

87-88 Duke get update head bolt torque. (Old bolt, 84-86 fiero, are known to be weak so don't reuse them.)
Get New bolts and torque to 87 service man, page 6A1-7 and 6A1-8

quote Head Bolt # 1 thu 8, install w/ oil Head Bolt # 9 & 10, APPLY SEALING COMPOUND PART. NUMBER 1052080 OR EQUIVALENT TO THREADS ON BOLTS SHOWN. (From Fig 12, page 6A1-7) • Cylinder head bolts gradually with torque wrench to 25 N-m (18 lb. ft.) in sequence shown in Fig. 12. • Repeat sequence, bringing torque to 30 N -m (22 lb. ft.) on all bolts except number 9. Torque number 9 to 40 N -m (29 lb. ft.). • Repeat sequence. Turn all bolts, except number 9, 120 degrees (two flats). Turn number 9 1/4 turn (90 degrees). (From page 6A1-8)

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave (It's also at the top and bottom of every forum page...)

Just spit in the hole and crank on it till your elbow pops! That's right out of the Redneck Backyard Budget Engine Rebuild Manual!

I know this is about a Fiero born in the 80's. But was just going to mention the torque specs for cast iron heads on my 72 Buick 350 says "lightly oiled" head bolts, thats in the service manual, and that is after chasing the threads in the block.
It seems there is no standard and you need to read deeper the source where you are reading the torque numbers to be sure it specifies either dry or not. I would suspect dry would drag alot. Wet would most likley be close enough to the same torque wether it is silicone sealant, anti seize, or light oil.

It sounds the general consensus seems to agree on lightly oiled. So by "lightly oiled", do we just mean common motor oil?

Why is anybody second-guessing the service manual here? Until the "general" population designs an engine of their own, I would rely on what the service manual says, not what the "general consensus" deems is appropriate. Reread the posts above and you'll see that half of the posters don't use any references at all for the way they build an engine except the "that's the way I've always done it" approach. Very scientific. The service manual states to coat the bolts with thread sealer and apply the recommended torque. You take your chances if you do it any other way, unless you know how to calculate the effect of a different method and adjust the amount of torque accordingly.