OK, well, I am installing an S&S 106 big bore kit and also had some significant head work done. After checking and ensuring all clearances are good, it's time for me to get these heads on here. Some tech details: using a 0.030 MLS Cometic Gasket and had the heads decked down to give me 82cc combustion chamber volume.

Anyway, I am using the standard head torquing procedure (HDs and well as the S&S recommended procedure) of going to 10-12 ft/lb, then to 15-17 ft/lb, then 1/4 turn (in proper sequence, of course). S&S states to do this procedure twice actually in order to set the gasket. They say to completely loosen the bolts and the proceed a second and final time. Well, I did the first round on the first head and am questioning if this is too tight. I am using a properly calibrated Snap-On tech-angle torque wrench so I know it's legit. I get the first 2 torques done, set my wrench to 90 degrees and turn it (I'm also visually ensuring it's going a full 90 as a double check). Well, the wrench tells me how much torque it took to get to the 90 degrees and, tbh, it seems pretty high. It's telling me anywhere from 58 to 66 ft/lbs. Yes, I placed head torquing lubricant under the head as well as the threads/shank. I get that there are schools of thought on both ways of torquing (angle vs end-value) and most folks who torque to an end value using stick to high 30s/low 40s for the twincam heads. I prefer the angle method for a number of reasons, but didn't really want to turn this into a discussion on best torquing methods., but I should still be in the ballpark of the end-value torque amount, I feel.

My question is this: Is this just the initial value while I set the gasket and the second final torquing will be a bit lower or do I have a legit issue going on? i didn't want to proceed with the second round to ensure I don't mess something up. I'm wondering if the decking of the heads took a lot off the overall height of the head, enough to cause the head bolts to bottom out before they actually compress completely and that's why I'm getting such a high torque value

I'm using Fueling headbolts and studs, btw and they recommend not using the 1/4 turn method and just going to 35 ft/lbs (in increments and proper sequence).

Anyway, any thoughts anybody? Thanks in advance...

 

I am runnin S&S heads and did the HD tq I didnt want to over think it. I am ok 13k later no leaks

 

Both feuling and cometic say torque to final. I would do that. HDs torque to spec and add 90 degrees is more for composite head gaskets that make crush a little during heat cycles. I typically use cometic procedure but only go to 39 fp. I've yet to have an issue this way on standard builds. I have seen studs pull from the case on evos using the standard spec and cometic gaskets. Not sure it's the problem but it got me thinking.

4 1/4 bore TC stuff gave me fits up until cometic finally emobosed the center part of their 3 piece gasket but that's a different animal..

 

I used cometic gaskets and their procedure and running problem free for 3500 miles so far. Instructions said to not use factory torque procedures

 

If you are worried about bottoming them out I would just check it on the other cylinder that you have not done yet. Simply screw the nut down with no head in place until it bottoms. Measure from the underside of the Nut flange to the cylinder deck. If you compare that to a head thickness measurement you will have your answer.

 

Using the 90 past lower tq and getting 68 fp means you are going to pull studs when the motor gets hot. The fancy studs change things.

 

When you move away from stock components you sometimes need to heed the recommendations of the replacement part manufacturers, this is one of those times, I have seen pulled studs, you can fix them but why go there?

 

we do 10,20,30 & finish with 42 here.been doing it since the evo`s were introduced,never had a problem or failure

 

Well, thanks for all the replies.

Good news, I just checked the bolts to see if I was bottoming out and all looks good. Using the short side, I measured the thickness of the head from the bolt shoulder to the deck was 1.267". The gasket is 0.030", giving me a total of 1.297" to the top of the cylinder jug deck. When I run the bolt down on the stud until it gets to the point where it stops moving freely (I could still get about a half turn on it but you can tell its digging into the part where the tap isn't fully cutting), I'm getting a pretty solid 1.001" from the jug deck to the bottom of the bolt shoulder....so plenty of clearance.

One question. I never did take a thickness measurement of the head before the work was done. Anybody know that value? I'd be interested to know how much was decked to achieve the 82cc.

 

Does this apply to M8s when tensioning the
heads
on Cometic MLS?