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Discussion Starter · #1 ·
Hi everyone, I am in the process of reassembling the front engine cover and heads for my 3800 series 2 supercharged from a 2003 buick park avenue ultra and have a few questions with reusing bolts. I already have the heads installed with new bolts, torqued down with proper angle but, I did notice that the bolts for the rocker arms, crank bolt, and even the bolts for the front timing cover are given a torque and angle spec in the factory service manual. Even the bolts to attach the oil filter adapter to the cover has a torque and angle spec. I know from previous experience to always use new head bolts that are TTY and the service manual explicitly says to use new head bolts, I am just confused with these other bolts that are given an angle spec but the book says nothing about having to use new bolts. I can see that the rocker arm bolts and maybe he crankshaft balancer bolt may require new bolts, but do the other bolts I mentioned before need to be replaced too?

Any help or insight into this would be greatly appreciated, thanks!
 

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For that area, rockers, cam, and crank bolts are TTY. The others aren't cranked hard enough to stretch, just require some teflon tape or paste (front cover, lower intake, and maybe oil filter extension).
 

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Discussion Starter · #3 ·
For that area, rockers, cam, and crank bolts are TTY. The others aren't cranked hard enough to stretch, just require some teflon tape or paste (front cover, lower intake, and maybe oil filter extension).
Thank you so much for your quick reply. I just never done extensive engine work on this car and never seen angle specs. on such low torque applications that's what threw me off. I wonder why those pieces have the additional angle spec. in the book. Maybe has to do with compression of the gaskets?
 

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That's been the case with most modern engine fasteners for a while now, even these ones dating back to the 90's for this iteration. I can only guess that they'd rather bank on a standard rotation angle after initial torque to guarantee a solid crank-down, rather than risking hitting a higher torque spec that may cause bolts to break while various calibrated wrenches are trying to hit the mark.
 

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TTY takes thread friction out of the equation in large part since the initial TQ is low to seat the assembly. thread pitch tells you how much the fastener will stretch/tension per * of rotation.

its just more consistent especially when you have a high speed assembly line and the 4,000 digital tq wrenches have to be calibrated/tested....and they arent getting calibrated/tested but once a month/etc.

ive reused rocker bolts but ive come across a few that stretched before i hit the final * mark. i just backed em out and used spares.

crank/cam bolts ive reused plenty of times along with front cover bolts
 
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