My Intake Manifold gaskets call for 11ft. lbs or torque for the bolts - to be done in 3 gradual stages.
when I put sealant on the bolts and start to thread them, I can feel them giving resistance to my hand-threading immediately after starting to thread them. I assume that this is because there is sealer on them.
How to you accurately get the torque correctly if there is sealant on them that causes more friction in the threads?

 

First question, where did the 11 ft-lb figure come from. I dont know any chevrolet intake that would be that low, except the top of an Cross fire plenum. That leads to the second question. How in H$#L are we to know what you are working on? Sealer generally wont cause a major difference in torque readings with that level of torque.

 

 

See Vortec Heads - SBC 350

 

What sealant are you using? Is it a thread sealer or something like permatex?

 

What is this supposed to tell us?

Scott

 

double post

 

use thread chasers or a tap and die to clean the old sealer out of the holes and bolts first

 

Scott - The torque spec for the Intake Manifolds on Vortec heads is 11ft./lbs. Oh, and keep your shiney a** out of my threads

 

This is called run down torque. Determine how many ft/lbs of resistance the sealant is causing and add the desired bolt torque to that.

 

Hmmmm....I did not know the Vortec heads and intake manifolds had such a low torque spec. I've never dealt with the combo, and old skool intakes usually have a torque spec of about 30 lbs. with an iron head, so 11 lbs. sounds ridiculously low to an old dinosaur like me. Here it is in black and white, though:

http://paceperformance.com/p-3981-torque-specs.html

Well, red and white, anyway. I think Mike Ward is on the money here. You can measure run down torque with a torque wrench by turning the bolt, (with a few threads showing) and gradually turning up the torque setting until it clicks. Add another 11 lbs. to that, and there's your final torque spec. Oh, and you can bite my shiny, metal a**! Good luck, and let us know how it works out, OK?

Scott

 

And then right below in the chart it says 35#. So what is it? I think I would get some more clarification.

 

Most GM bolt specs are for "dry" bolts. If they are to be lubed, it is with a special call-out note and should be included in any formal GM documentation.

Aside from that, if lube (or sealant) is added to a bolt having a 'dry' specification, the amount of torque should be REDUCED from the dry spec, as the sealant would act as a lubricant--reducing the friction of the threaded joint as it is tightened. [Sorry, Ward...you're wrong, again.]

The purpose of fastener torque specifications is to put a specific amount of tensile stress into the fastener, such that it is stretched...but not beyond its 'elastic' limit. That maximizes the holding power of that fastener without causing damage to it.

Many automated fastener torquing systems these days tend to use "torque angle", rather than an amount of applied torque: the fastener is engaged to the point of a specific light loading which gets it solidly mated with the other threaded member; then, it is rotated a fixed number of degrees of rotation. That loading is more accurate and directly proportional to the correct stretching of the bolt--whether it is lubed, or not. But, we don't have the knowledge needed to do that on our engine's/car's fasteners; GM doesn't specify 'torque angle' for C3 fasteners.

Suffice it to say that a fastener that is "slicked-up" with any substance that reduces sliding friction of the threaded members with each other, will require much less applied torque to achieve that same 'torque angle' as it would with dry fasteners. With oiled members, that's generally around 30% less. Not sure how much less permatexed bolts should be torqued; but I'd estimate something in the 20-25% less [than dry specified torque] values.

Apply the same torque wrench load to a lubed bolt and it will exceed the elastic limit of the material and the fastener will be significantly weakened and the retaining load greatly reduced. Small fasteners may actually break under such loading, as their allowable tolerance is much less than for larger fasteners.

If you have purchased "specialty" fasteners for an engine build, bolt loading should be appropriate for the retaining loads that the engine manufacturer intended. But, the bolt manufactuer may state that their bolts should be torqued (and loaded) much higher. If the parts are steel and the parts' material specs are not exceeded, that may not be a big deal. But, if the parts are aluminum (or magnesium), such increases in fastener load could cause performace problems...or even early failure...for the parts they are being used to retain. This is a potentially troublesome issue that neither the original vehicle manufacturer, nor the [new] fastener manufacturer seem to want to delve into. But, it can cause real problems for us, if we don't take such issues into consideration.

 

Not arguing here, just trying to understand better. The OP says he can feel more resistance to turning the bolt when the sealer is applied. Shouldn't that mean you need to overcome that resistance in order to achieve the correct amount of bolt stretch?

Also, wombvette, good eyes, man!

Scott

 

You don't vary torque when using sealer as it's neglible. Some of the intake manifold bolts on both big and small blocks require sealer but nowhere does it say in any service manual to add torque for those bolts. I guess if it makes you feel better you could always go an extra pound on the sealed bolts....

 

Thanks for all the replies...I did my homework on this 11 ft. lb thing and its true - sounds like an oddball # yes?
The thread sealer make it feel less "slicked up" and more of a drag. I would guess that more torque is needed but ??

 

Feeling 'extra drag' on a Permatexed bolt when you are starting it (very low actual torque value applied) would be normal. But, once you apply enough torque to the fastener, just about any 'fluid'...regardless of how thick it is...will become a lubricant to metal-to-metal thread surfaces.

If you "goop it up" so much that the Permatex fills the available airspace below the bolt (and creates a hydraulic lock), that is another issue. I'm not sure that's even possible with properly designed parts and just enough sealant to fill a few threads at the end of a fastener (all that is needed to seal the threads against possible oil leakage), but too much is not "better".

 

good stuff here...

 

I've always used my precisely calibrated wrist for intake bolts....never been an issue for the past 20+ years...

 

OK, I guess that makes sense. Thanks, 7T1vette. Well, I've learned something new today, I guess I can go back to bed now!

Scott