I wanted to confirm this before I go further--heres the deal.

I need to put Helicoil inserts into my RPM heads. 2 per head , the #2 / #4 holes / rocker shaft stands --the long studs/bolts .

since the threads are pretty far down in the rocker stand...want to be sure on how deep to drill .

so the Helicoil is about .50 deep. Do i need to simply drill the factory hole .50 deep and thats it? Or does the insert need to go deeper in these particular stand holes ??

Checking before I drill !

Im using studs not bolts on these 4 holes

You can heli-coil the 1/3/5, but the 2/4 wont have enough material because those holes are in the common divider walls of the intake ports.

well....the threads are ripping out...so... ??

Maybe someone who does this stuff for a living can suggest a repair.

Were you using studs or bolts in those positions? And what sort of spring loads were your rockers shaft assemblies subjected to?

Studs...400lb open

Bob at MCH repaired one of my heads after the engine let go, did a real nice job.
Mick

try calling Edlebrock and ask them about this

Heli coils are pretty simple, you must have enough material to drill the hole oversized to tap it for the coil and you need to measure the depth of the hole. The best would be to be able to be deep enough to use the entire coil but Have cut the coil down in the past to shorten it for a hole that is not deep enough. also the hole MUST be drilled strait and taped strait. If any of this seems too much for you have a professional do it.

They also have longer than the standard 1/2” long helicoils in some sizes. I did buy a box of 3/4” long helicoils in 3/8” size from one of the big suppliers of fasteners and hardware on the net. If it is possible to repair, i would try to use the longest that is possible. I think the company i used was Mcmaster Carr or MSC industrial. Good luck

If the heads are heavily ported, there’s a possibility you’ll break through into the ports when you drill over size for the heli-coil.