Head Bolt torque to angle methodology discussion - Saab Vintage Models Bulletin Board - Saabnet.com
NG900 & OG93 |
Vintage Models |
Clubs & SOC |
Other Cars |
Books Movies & Music |
Member Photo Galleries |
Member Directory |
*Buddy Registry |
*Mileage Registry |
What's New |
Photo of the Month |
[Main Vintage Models Bulletin Board | Post Followup | BBFAQ ]
[ Prev by Date ] [ Next by Date ] Member Login / Signup [Most Recently Edited Saabnet.com Photo Galleries]
Head Bolt torque to angle methodology discussion
Posted by Don Wollum [Email] (more from Don Wollum) on Thu, 30 Nov 2017 07:46:26
Vintage Saab dealer factory tools for 2strokes had degree plate for rotation of head bolts once basically all bolts were screwed down in pattern to say hand wrench snug "standard. Then the angle plate was set to 30 degrees and when breaker bar movement clockwise met the "0" the head bolts were torqued properly. This was before the invention of stretch head bolts, and before calibrated click type ( read accurate ) 1/2 in torque wrenches were developed. What was in use were "springer" torque wrenches that measured tork by metal near where the socket afixed was designed to twist and the needle was reacting to arm strength applied and the needle moved and the metal 20-120 pounds on the scale plate up near the handle gave 50 pounds torque when big steadily increasing pull on handle was progressively given my technician. Springers in use were hard to execute
pulling and also observing the wavering needle, and were only calibrated once after manufacture.
Click Porque wrenches I suggest are better for ensuring head bolt torque uniformity all around, and are even better than the angle method Sabb and industry thought was an improvement at the time ( early 1960"s)
regular head bolts do stretch when torqued, and that value has to be above the over time compress ability of the head gasket material itself.
say torque head bolt to 50 pounds, 20 of that will ease away with gasket in use ( heat cycles ) compressing. and 30 pounds remain for securing steel rings that seals combustion chamber gasses alone.
retorque at 600-1000 miles, setts the clock again and the gasket shrinking any more in the future about 5%, leaving the bolts to efectively apply 40-45 foot pounds of clamping pressure.
posted by 71.50.124...
Posts in this Thread:
Post a Followup
No Site Registration is Required to Post - Site Membership is optional (Member Features List), but helps to keep the site online
for all Saabers. If the site helps you, please consider helping the site by becoming a member.
This is a moderated bulletin board - Posting is a privilege, not a right.
Unsolicited commercial postings are not allowed (no spam). Please, no For Sale or Wanted postings, SERIOUSLY.
Classifieds are to be listed in The Saab Network Classifieds pages.
This is a problem solving forum for over 250,000 Saab owners, so expect to see
problems discussed here even though our cars are generally very reliable. This is not an anything goes
type of forum. Saabnet.com has been a moderated forum since 1988. For usage guidelines, see the
Saabnet.com Mission and Purpose Page. Please remember that you are
not anonymous. Site Contact | Site Donations | Other Sites by SP -
Your address is: 184.108.40.206 - Using CCBot/2.0 (https://commoncrawl.org/faq/) - Logged.
Site Members do not see red text instructions, bottom of the page anchor ads, or box ads.
Click here to see all
the Site Membership Benefits!