VCCA Home Forums TECHNICAL - GENERAL Mechanical - Engine, Trans, etc 207 head bolt torque values

I've looked in the manual, there is a sequence all right but no torque values. I consulted the forums via search and 70 ft/lbs seems to be the accepted figure. Is that correct if I reuse the old bolts? Should I buy some new grade 8'd and give it 100 ft/lbs ?

Hi Pat
I took a photo of a page out of the Motors Auto Repair Manual. It lists 1935-6 at 75-80 ft lbs (34 is the same). I would not go any higher. Now that you have grade 8 bolts the weak link is the cast iron threads in your block. 75-80 is fine. Also included is a tightening sequence photo.

Click here for info

Thanks Dale.

70 to 80lbft is about as tight as most head bolts in a lot later engines go. Some of the latest engines use torque to yield which do end up a lot tighter but cast iron and alluminum have improved since the 207 was cast.
Tony

Check the threads of those old bolts for stretching before re-using them.All threads should have same distance between them judging with your eye,they stretch at the threads,stretched ones you will easily spot.They tend to snap off.Would not go above 70 foot lbs.with old unstretched re-usable bolts.Motors manual torque figures are a bit high for '36

Don't know that going to 100 lb. would add anything. Because of the gasket being designed to flatten enough to make a proper seal for the water passages and the cylinders, I would think that in this case "more is less." Just my opinion.

As for me I would use a torque wrench and proper sequence and chose the middle ground of 75 foot pounds. I would start out at about 55 pounds to start with and increase to 65 and then finnally to 75. After all, all you're looking for is getting a proper seal for the head gasket, nothing more. There is probably nothing to be gained by squishing the head gasket as flat as a "railroad penny" as 100 pounds would do, so to speak.
Good luck,
Charlie

Charlie,

I ended up reusing the old bolts and torquing them to 75 ft/lbs.

I think the real reason that degrees of "TORQUE" are recomended is
1... To make sure the bolts are TIGHT ENOUGH.
2... To make sure all the bolts are CLOSE to being tightened somewhat EQUALY.
3... AND MOST OF ALL...to try to keep some folks that think brute force is best in any situation from BREAKING the bolt's......ED

I have broken new head bolts tightening to the manufacturers specs with "torque to yield" bolts. Some of them are ridiculous upto 10lbft then 270 degrees rotation, it would be interesting to find out what the finished lbft was in this situation.
Tony

That should be easy enough by using a clicker wrench afterwards and move the clicker up slowly until you get to where it barely moves before clicking. I suppose you could even use a regular torque wrench to see what it reads at that point. It may not be actual, but it would be pretty darn close. Check them all and then average them.

Richard
You are right, both methods would work. I have only used the "torque to yield" bolts in a work situation with customer cars therefore not had time to play.
Tony

I'll show my ignorance, again. What in the world is a "torque to yield" bolt?

I've tried to imagine such a thing but can't seem to grasp the concept.

Help!
Charlie

CHARLIE...GOOGLE "TORQUE TO YIELD".....UP POPS THE ANSWER (WITH PICTURES FOR THE FOLKS IN NC)....MAGIC......ED

Hey....None of that! Lighten up on my man Charlie there. We Tarheels are very sophistumicated. You-uns leave us-all alone, ya hear?

All the Best, Chip

Chip.....I am glad you picked up on that I was not shooting at you or others from the fine NC county.
I love the mountains and am a 2nd. generation appalachian.
I play Bluegrass Music. Mandolin, Guitar and can fiddle till the real fiddler gets there. Some of the best Bluegrass musicians ever, came from North Carolina. I used to travel there to the "Old Time Fiddlers Convention" in Union Grove It is the oldest music festival in the country.....SO...Pick Away On The Old Banjo And Keep That Guitar Strumming Put More Water In The Soup...There's Better Time's A'Coming...ED

Ok, I googled it. I read enough that I don't want nothing to do with them. The standard bolts are plenty good for my old Chevrolets. I've never had a problem yet with sufficiently torquing head bolts to specifications.
Charlie

Charlie......Hooray for you ...I agree with every bone in my body.
Is not anything sacred anymore???. Even the humble head bolt can not escape the wrath of the folks who want to modernize even the simplest of things....I say " ARISE AND REPEL THESE INTRUDERS WHO WANT TO LEAD US DOWN THE SLIPERY SLOPE OF COMPLEXITY ......ED

The "torque to yield" bolts have become common in a lot of vehicles lately including those with GM badges.
They are a single use bolt, if you undo it you throw it in the bin and replace it, and not only used as head bolts either.
Tony

Sounds like a "Torque To Yield" manufacturing company would be a good investment place to buy stock in.
If one can only use them once and then have to throw them away there will be a market for them forever.I see them being used everywhere soon because of the $$$ to be made....ED