Machinist's advice sought - Page 2

Verne_Frantz · #11 08-26-2016, 03:37 AM

That's why I'm afraid. Some went ok and some hit water. Not much meat there, I guess.

Verne

Verne_Frantz · #12 08-28-2016, 05:28 PM

Well, I took a close look at the stud. The crack only goes down to the pin hole. Surprisingly, (or maybe not since it was built as a race motor)the studs are threaded and there's no damage to the threads from it breaking off. I'm seriously thinking about just replacing the stud and living with the crack. I would drill it and re-pin it. The crack has no where to travel because it stops at the pin hole and it's only the top 1/8in. Am I crazy??

Verne [img]<<GRAEMLIN_URL>>/dunno.gif[/img]

68l30 · #13 08-28-2016, 06:49 PM

I think it all depends on your spring pressure. Anything above stock I would be concerned. Make sure you have plenty of thread engagement under the cracked area.

BIG

Verne_Frantz · #14 08-28-2016, 07:03 PM

No heavy duty springs BIG. Just OEM. These '09s don't like to rev that high anyway so they don't need a ton of pressure (stock cam).

Verne [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

**Paul_S** · #15 08-30-2016, 03:14 AM

Should only drill and pin off to the side of the stud to remove minimum stud material. Threaded stud is best and needs nothing else. If all have been replaced with threaded studs and also pinned, I'd remove the pins & drilled studs (scrap them) and replace with new studs only.

Paul

EZ Nova · #16 08-30-2016, 12:03 PM

Verne, FIX THE HEAD! Weld up the crack or you're just asking for trouble down the road. It's not a big deal. BUT send it to the best head guy you can find, maybe Dave Mills will help???

Piston is an easy fix. Take it out and get it checked for cracks. IF NONE FOUND, just sand off the sharp edges with a dremel or similar tool and re-use the piston. Deburr any and all sharp edges and you will be fine as long as the gouges are not too deep. But being a 409 there should be a ton of meat there.

Good luck, John

Verne_Frantz · #17 08-30-2016, 02:30 PM

Thanks for the opinions. As for the piston, that was my plan (as long as its not cracked). The stud broke for two reasons. One is that it was weakened by the pin hole and two because the Intake valve head got caught under the exhaust valve. I don't plan on drilling the new stud.
As for the crack, I'm still not convinced it might cause more problems. It can't go anywhere because it ends at the pin hole and there should be no side to side thrust on the stud. Once the old stud is removed, I'll see how far down the threads go.

Verne [img]<<GRAEMLIN_URL>>/biggthumpup.gif[/img]

**Kurt S** · #18 08-30-2016, 05:43 PM

Threaded and pinned is like belt and suspenders. Actually worse since the pins cause stress risers. I agree on pulling the pins...

resto4u · #19 08-31-2016, 01:07 AM

There was no real reason to pin a threaded stud. That was usually only done on push in studs for some that had higher than stock spring pressures.

Verne_Frantz · #20 08-31-2016, 02:15 AM

These heads were made about a month after the factory started pinning them so the pins were already there. I guess someone decided to replace them after adding the screw-in studs.

Verne