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When I put the head bolts in I saw the torque spec in the service manual (45 NM I think), but I didn't see that on the back page of the chapter in the specs it also says to tighten the bolts an additional 90 degrees after reaching the torque. I didn't do this, and now I have the engine halfway back together. How important is that last 90 degree turn?
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Last edited by dnalbach; 11-16-2006, 07:19 PM. -
Originally posted by dnalbach View Post
More important than the first 45NM... The head bolts are torque to yield bolts. Torque to yield is the method of tightening a fastener so that a high preload is achieved by tightening up the yield point of the fastener material.Last edited by bszopi; 11-16-2006, 07:44 PM.-Brad-
89 Mustang : Future 60V6 Power
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Please tell me you replaced the head bolts...........Comment
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If you didn't use new head bolts, get new head bolts.
And if you don't do the 90º turn, now, you're gonna do more work later.
To add to what Brad said, torque to yield bolts actually stretch, and if they're reused, they stretch more than they're meant to, and a snapped head bolt is something nobody wants.Franz
1990 Z24-NA 3.1L
14.72 @ 92.24 MPH
14.89 @ 94.92 MPH
The boost is coming....Comment
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id just go back and torque the additional 90* ... but thats me..1996 beretta w/a 04' 3400 3.5 top end, 42.5lb hr, 180*thermo, t3t4 .63ar 60 trim, LC1 WB, FMIC, greddy rs BOV,TIAL 38mm wastegate,791xv,fidanza,stage III clutch,TG LSD,ffp udp,walbro 255 lph,strut tower brace,22 rear sway,30 front sway,92 5sp tranny,92 subframes,all solid mounts,kyb shocks and struts,eibachs,battery in trunk,tgp map sensor,DHP Powrtuner,euro front and rear and more to come soon...mods sitting in boxes waiting install....zo4 kit,GTU wing,and more..Comment
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YES, I did use new head bolts. I'll go back and torque the extra 90 degrees and try to be grateful I wasn't completely finished yet.... hate that AC bracket...../sigh
By the way, is torque to yield the reason why a lot of the head bolts "popped" with a little puff when I went to remove them?Last edited by dnalbach; 11-17-2006, 06:54 PM.Comment
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