Yet ANOTHER head bolt torque question...

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foundationapps
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Yet ANOTHER head bolt torque question...

#1

Post by foundationapps »

Hello, me again.

While doing other tasks on the Panhead rebuild, I got back to torqueing the head bolts on the front cylinder. Changed the gasket to a James. Bolts are 12 point. I have a curved wrench and I rigged up a bolt head so that I could use a 1/2" drive bar type torque wrench. Not having any experience at this, I decided to go 10 ft. lbs. at a time, criss crossing the pattern and marking each bolt with a white paint dot on a fin so I knew that I was getting all 5 bolts in a criss cross pattern. Maybe this is anal and over thinking it, but I did 10 lbs, then couple of days later 20 lbs, 30 lbs, and so on.

Went to go to 50 ft. lbs per head bolt. Wife is bear hugging the motor so it's solid. She's a strong Wyoming girl, so it doesn't move :) As the wrench went through 45 lbs or so, the bolt heads ALL continued to turn WITHOUT the torque values increasing past 45 ft. lbs. Broke out in a cold sweat as I could image in my head, threads being ripped out of the STD head. I went around the pattern again, but the bolts did SEEM to get tighter, just no more than 50 ft. lbs. per bolt.

Now, Is it possible that the fire ring gasket is just compressing the metal ring? I can't imagine the threads tearing out of the head, not an STD head and not at 50 ft. lbs. ANY input is greatly appreciated!

Respectfully, as always,
Buddhahoodvatoloco
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Re: Yet ANOTHER head bolt torque question...

#2

Post by Buddhahoodvatoloco »

Wow, that is a thorough exercise in torqueing the head bolts, I usually juts crank them dam near snug, then get the torque wrench etc. then go to the specific torque value. In the pattern suggested of course. What comes to mind here, is the adapter you made, it might be giving you a false read, your'd have to seriously crank on the bolts 12pt. or not to strip them. But, yes the gasket does compress, good luck. Check your adapter and get the correct adapter for a true read.
foundationapps
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Re: Yet ANOTHER head bolt torque question...

#3

Post by foundationapps »

Thank you sir. What I'm doing is definitely probably doing wrong. I have a 12 point limited access wrench with a nut and bolt in the 1/2" end. I then put the 1/2" extension (with a socket for that bolt) from the torque wrench into THAT 1/2" box end. I keep everything so that there is a straight line from the bolt head to the meter on the wrench. HOWEVER, the is the 1" dogleg in the torque wrench end of the........ack, this is even giving me a headache. The effective length of the torque wrench is 20". I'll figure it out. Much appreciated.
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Re: Yet ANOTHER head bolt torque question...

#4

Post by Weedy »

foundationapps I am a mechanic by trade and have rebuilt many diesel engines. it sounds like your homemade tool is flexing. to torque my heads I have a snapon wrench that has a 9/16 12 point on one end and a 3/8 drive on the other. snapon p/n frdh181. if you cant find a snapon guy you could make one. the length is around 2 t0 3 inches. I don't recommend using extensions or adapters if you can help it. they lessen the torque and I don't know a way to calculate by how much. good luck tim
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Re: Yet ANOTHER head bolt torque question...

#5

Post by nmaineron »

I have been at this a few years my self and not once have I ever used a torque wrench on the head bolts.I have however bent and twisted a ew wrenches to get the task done.I have one 12 point and two six pointers I use for the different types of bolts.I prefer to use six point but they are harder to get the wrench on the inside heads.It is nice to have a good clean snug thread and they really should be dry but I like to use a bit of never seize on the threads.A dry tight thread will give you a different reading than a loose thread.I just get them all to a good tight spot incrementally where I can't turn the wrench with a good strong pull and call them tight.I have never had a head gasket failure due to a loose bolt.It's a good idea to check them after a few good heat cycles but never tighten them while hot for chance of pulling threads out of the heads.
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Re: Yet ANOTHER head bolt torque question...

#6

Post by awander »

If you add an extension that makes the torque wrench longer, you will get incorrect readings on your torque wrench.

xxxx----------------O------o

However, if you can get the torque wrench and the adapter to be exactly at right angles to each other, then the torque wrench will read the actual torque you are applying to the bolt.

xxxx---------------O
|
o
foundationapps
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Re: Yet ANOTHER head bolt torque question...

#7

Post by foundationapps »

Hey all, thanks for taking the time to provide some great information. As is typical my Gerry rigged setup is a bit odd. This is a keyboard layout using Awander's method of explanation, which is a good way by the way...

(handle) xxxxxxxxxxxxxxxxxxxxxxxxxx-------------0 0-------0 (C-shaped limited access wrench)
\ / \
\ / \
(1/2" box end with nut/bolt) ----> 0 0 (12 point head bolt).


Hopefully that makes some sense. The wrench one of those C-shaped limited access jobs that end up with the angle being 90 degrees to the bolt being torqued. NOT having an adapter, I put a bolt and nut through the 1/2" box end of the wrench. THEN, using a socket on the torque wrench, I attached that socket to the bolt and nut rig on the box end of the special wrench.

Looking at the rig from above, it's a straight line off the 12 point head bolt, but with a "V" in the setup 14" away from the head bolt. Ultimately, it's a straight line from the head bolt to the handle of the torque wrench.... Sheesh, that gave me a headache just writing it.

Doing the math on a straight 6" extension of the torque wrench with NO angles, I calculate 52 ft. lbs. to read on the torque wrench scale. Total bar length is 20". I can only imagine the number of fore head wrinkling and headaches I just induced out there, my apologies. I don't give up easily :)

Most respectfully,

OKAY, that keyboard sketch didn't work out. I'll take a PICTURE of the rig tonight. Though this is a big town, no one has the right adapter. I'm trying to do an accurate jury rig of the deal.
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Re: Yet ANOTHER head bolt torque question...

#8

Post by awander »

Just put your adapter rig on the torque wrench so that you have a straight line from handle to the end of the torque wrench(of course), and then the head bolt ends up at the end of a second straight line that goes off at 90 degrees from the end of the torque wrench to the head bolt.

Don't worry about the curved wrench in between; as long as the head bolt is off the end of the torque wrench by 90 degrees, you don't need to calculate anything; just read the numbers off the torque wrench as usual.
foundationapps
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Re: Yet ANOTHER head bolt torque question...

#9

Post by foundationapps »

Andy, that makes perfect sense. Thank you sir.
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