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1929 29-25 Cyl head bolt torque setting req?


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I do not think the head bolt tightening sequence is correct on that non GM worksheet.  It goes against how I have been taught long ago about tightening cylinder heads.  This is the correct head bolt sequence from GM for 1926 Buick.   The Buick head is an odd bolt layout.  It is treated with some bolts that are close together "as pairs" and works it's way in a circular pattern from the middle to the ends.  Working evenly from the middle to the ends is how we do it today.  That other one is very non conventional and I have never seen anyone tighten bolts down one side starting from the middle.   That drawing has made it's rounds.  This photo is from the 1926 GM export manual.  

 

Also made an update to the attached thread.  This error is likely in many places where people have asked for Buick torque and head tightening sequence.    Hugh

1716461986_torquesequence1926Buick.JPG.bf13a8cb12505c6de78a798052f087b8.JPG1288236580_Torque1929BuickTorqueandHeadtighteningsequence.jpg.48faf67243e1277908ff9409610c9c38.jpg2000310444_Torque1929Buicktorquespecs.jpg.b0ca79ba2405f1730d26eb504255ed5f.jpg

 

Edited by Hubert_25-25 (see edit history)
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7 minutes ago, Hubert_25-25 said:

See my update to the attached thread.  This error is likely in many places where people have asked for Buick torque and head tightening sequence.    Hugh

 

Thanks. I didn't see the update. Just the original pic.

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1 hour ago, Hubert_25-25 said:

I do not think the head bolt tightening sequence is correct on that non GM worksheet.  It goes against how I have been taught long ago about tightening cylinder heads.  This is the correct head bolt sequence from GM for 1926 Buick.   The Buick head is an odd bolt layout.  It is treated with some bolts that are close together "as pairs" and works it's way in a circular pattern from the middle to the ends.  Working evenly from the middle to the ends is how we do it today.  That other one is very non conventional and I have never seen anyone tighten bolts down one side starting from the middle.   That drawing has made it's rounds.  This photo is from the 1926 GM export manual.  

 

Also made an update to the attached thread.  This error is likely in many places where people have asked for Buick torque and head tightening sequence.    Hugh

1716461986_torquesequence1926Buick.JPG.bf13a8cb12505c6de78a798052f087b8.JPG

 

I agree with Hugh on this being the correct head bolt tightening sequence.

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20 hours ago, Hubert_25-25 said:

I do not think the head bolt tightening sequence is correct on that non GM worksheet.  It goes against how I have been taught long ago about tightening cylinder heads.  This is the correct head bolt sequence from GM for 1926 Buick.   The Buick head is an odd bolt layout.  It is treated with some bolts that are close together "as pairs" and works it's way in a circular pattern from the middle to the ends.  Working evenly from the middle to the ends is how we do it today.  That other one is very non conventional and I have never seen anyone tighten bolts down one side starting from the middle.   That drawing has made it's rounds.  This photo is from the 1926 GM export manual.  

 

Also made an update to the attached thread.  This error is likely in many places where people have asked for Buick torque and head tightening sequence.    Hugh

1716461986_torquesequence1926Buick.JPG.bf13a8cb12505c6de78a798052f087b8.JPG1288236580_Torque1929BuickTorqueandHeadtighteningsequence.jpg.48faf67243e1277908ff9409610c9c38.jpg2000310444_Torque1929Buicktorquespecs.jpg.b0ca79ba2405f1730d26eb504255ed5f.jpg

 

Many thanks Hugh, That is the correct picture of my cyl head.

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In my opinion, the real key to torqueing cylinder heads is to torque in small increments,  I usually start at about 25 ft-lbs, starting near the center and working circularly till all are done. then I torque again at 35ft-lbs circularly again.  I keep working up in increments until the final desired torque is reached.  Then after running the engine to get it warm, do one final check.  

 

The torque settings are also dependent on using the original correct grade of headbolts.  Too many people think a grade 8 bolt is better than the original grade.  The purpose of torqueing the bolts is to get the correct stretch in the bolts so they maintain tension throughout all operating conditions.  

 

Bob Engle

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