Timing belt tensioner mountimg studs

8x1.25

 

What? how ?

 

It's easier to brutally mangle a M8x1.0 nut down a M8x1.25 stud than a M8x1.25 nut down a M8x1.0 stud .

 

Well, I shouldn't talk ...

 

I'm just as shocked as you (and just guessing), and hope that the OP posts some pics of the destruction (but what I posted is true -- M8x1.0 nut on M8x1.25 stud requires much less deformation than the other way around).

 

I once completed an entire repair using a helicoil for a 10mm x 1.5mm hole, only to find out the correct pitch was 10x1.25. I actually have forgotten how we I got it to fit.

 

I'll take a helicoil 10:1 over a time cert anyday but for just such screwups they make a 'BIG CERT" Has an overly large OD. Had to put one in a head for an intake manifold stud repair recently. Saved me from some welding and machining.

 

BIG CERT'S are awesome!
I redid all of the head studs with them once in one of my twin turbo 5.9l Cummins diesel race motors. It pulled the threads on a couple studs and the block had a whole lot of specialized machining done to it so I figured I would try the BIG CERT's first before spending the money machining a new block. They held the head down with 1,800 hp and 110 psi of boost!

 

Threads can easily be determined with a thread pitch gauge. They are cheap, widely available and everyone who works with bolts should have both a metric and Imperial set in their tool box.

https://www.lowes.com/pd/IRWIN-Standard-SAE-Thread-Gauge/1003087518
https://www.lowes.com/pd/IRWIN-Metric-Thread-Gauge/1003087516

Image Unavailable, Please Login

 

If I recall this correctly, the studs have different tighter tolerances to the block. Not sure it is a problem but good to know if making a stud on your own. It should be a tight fit in the block, but normal fit with the nuts.