7/16" rod bolt stretch spec

[Tim S.]

We are rebuilding a 1969 model year IT code L88 engine. The rod bolts are the boron alloy 7/16" factory bolts
used with the dimpled rod with the floating factory pistons in the closed-chamber 842 aluminum head.
The engine is very low hours and all the parts are in great shape. The engine builder wants to use a stretch gauge
when he reinstalls the rod caps. He is asking about the factory spec stretch length at 70lb torque. The treads would be lightly oiled.
Can any one tell me the length specified for that bolt?
Thank You
Tim

[Richard F.]

Re: 7/16" rod bolt stretch spec

Chevy manual calls for .009 inch stretch. 67 -73ft/lbs

[Tim S.]

Re: 7/16" rod bolt stretch spec

Richard thank you for your quick reply! May I ask what Chevy manual has this kind of information?
Tim

[Richard F.]

Re: 7/16" rod bolt stretch spec

Chevrolet Power from 1984. Has a section on building each of the various Chevy engines, and one section on readying a Vette for racing. Includes things like strengthening the frame and other esoteric goodies.