I have a set of katech head studs I am going to install on my 2009 ZR1...There are several issues that I'm running into that I'm hoping someone can clear up.

--there is no info in the box. Does anyone have the final torque spec fir the M12 head studs? ARP Head BOLTS call for 130 ft/lbs, but I want to make sure studs are the same.

--the M12 Katech stud only has about an inch of threads on it where it screws into the block. This seems odd to me because there is roughly 2" of threads in the block...is there a reason why they aren't as long as a ARP or factory bolt is and only use the top inch of threads in the block?

--When the M12 Katech stud is screwed into the block and fully seated (when the stud's shank hits the threads) and I put on the head, then the washer...the bottom thread of the stud is just about flush with the washer. I have milled the head .030" and am using a .012" thinner gasket (so approx .042" shorter overall). There isn't enough thread depth there to properly torque the nut without bottoming out/running out of threads of the stud. Yes, the holes are cleaned, chased, and blown out. The studs are screwed in as far as they can go and each one is like this. With the nuts bottoming out on the stud before proper torque is met, this will be a major issue.

It it seems like these studs might be incorrect, but the box and part numbers all jive. Does anyone have any experience or info with these?

Thanks!

 

They had the same issue with the LSA engines, although I know they are completely different stud diameter. Check with Katech.

 

for one thing head studs do not require any where near the torque that head bolts require.call Katech

 

ARP head studs final torque recommendation is 80ft pounds for LS2 style head studs, so my guess would be close to that number.

 

80 ft/lbs for 12mm studs too?

ill definitely be talking with katech tomorrow about it...I was more just curious to see if anyone has noticed these same things I have with the stud length/depth.

 

Good question, I should have been more specific. Those torque numbers are for ARP head studs for a LS2 set up.

 

Spec for m11 arp head bolts is 75 ft lbs. Are m12 really that much higher?

 

I too think is 75 lbs max I don't care what the stud specs are we are dealing with aluminum threads 75 lbs is all that's needed and safe.

OP you need ARP head studs they have longer threaded area very important for the life of the alum threads.

I have my Frick Flow milled .150 thous and single washer no problem using their hex head bolts.

I was tired of putting up with heads studs upper fine thread damage due to nearby headers so is back to bolts for me.