https://www.tmzperformance.com/shop/...ldered-dowels/

These.
When you use high torque on the head studs, the alloy in the head will crush and bow.
These support the head stud bore, so when you tighten the head studs higher than normal, the stud holes wont deform.

 

As far as I know mine are stock. I do not remember seeing these or buying them when the engine was put together. If I remember correctly the headstuds wer tq to 105 ft lbs if my memory serves me correctly. I know it was what the specs said to tq to.

 

I've found it's not so much the torque, but how much power the motor makes. It's also an issue with ARP using small nuts and washers.

Machining the register flat and using a large diameter washer AND nut (arp has big nuts for 7/16 thread that the L19's studs have). This works well below 1000whp. The inserts help when going above that.

 

Lol you said they have big nuts lol. Something you wanna share with us here?

 

Do you remember part number for those big nuts from arp? I ordered nuts from Mc master carr (90759A660) and when I received them I notice on the nut says ARP 7/16-20 and the socket that I need to use for them is 5/8 socket. I am just wondering if it is the same nut. Thanks!

 

That's pretty nice solution to be honest with you. I think I will order them. Are you using them?

 

I don't have the part number off hand. But the bigger nuts do take a 5/8" 12pt. So sounds like you have the right one.

The socket is hard to get in there with the valve springs, so I have a "custom" ground down thin wall lol

 

No sir - but ARP offer similar solutions on their website too.
I dont know the part numbers, so you'll need to dig through the ARP website "ARP Insert washer".
The TMZ option is probably better as the sizing will be correct for Evo

 

I’ve used HKS on a lot of builds with great success. The rolled stopper layer adds about .006” around the cylinders.