1/2 head studs

[lengel]

I took my head off this past week, do a cracked from the center core plug over to the #3 spark plug hole. Any way I was looking at the 11mm arp studs and was wondering at what power level these would need to be upgraded. I decided I dont want to find the limits of the 11mm stud, and will be upgrading to a 1/2" stud. Im going to be making a fixture that will allow us to drill and tap the block with out taking it out of the car, and it will be perfectly perpendicular to the deck of the block using a hand drill and hand tap. This is the arp part # ar7.562-1lb (studs) # 200-8513 (washers) # 300-8304 (nuts) the total price was around $160. hope this gives us some added insurance the high hp TIII being built.

Adam

[turbovanman²]

I don't think anyone has ever found the limit, not sure what SMP used.

[lengel]

I heard he was running 1/2"

[Wayne]

I have 1/2 head studs on my Tlll motor.It was pretty easy to do but all the arp studs weren't perfectly straight. Each stud is marked to go in the same spot it came out of when going back together. You also can't put the studs in and slide the head down over them. My block was taped at the machine shop to make sure everything was straight.

Wayne

[lengel]

I have 1/2 head studs on my Tlll motor.It was pretty easy to do but all the arp studs weren't perfectly straight. Each stud is marked to go in the same spot it came out of when going back together. You also can't put the studs in and slide the head down over them. My block was taped at the machine shop to make sure everything was straight.

Wayne

Wow! arp studs a centerless ground. and should be straight as a arrow. What size clearance hole was drilled in the head?

[Directconnection]

Adam, we used to employ a former Honda tuner from VA that built some decently high hp hondas, etc.. (600+) He SWEARS by the Golden Eagle studs as they have that pilot/tip at the bottom. They were having issues with the arps, and this brand took care of all their problems. Since we use ARP's made for an Acura/Honda.... they should have something that works (I hate how the arp studs felt when torquing them with the torque plate...)

[rich tideswell]

golden eagle link http://www.goldeneaglemfg.com/index....ex&cPath=76_99

["Top Fuel" Bender]

been 10+ years since I was looking at them
but double check the minor dia. of the 1/2" stud versus the drill hole size left from the 11mm stud
I think I remember the % of thread engagement being slightly less then optimal and wondering if the increase in stud dia. was worth the decrease in the thread
I know many have used them for years but...then again my 10mm-11mm survived for many years of abuse
maybe a roll tap would help too
just some food for thought

[Directconnection]

Roll tap uses a smaller diameter tap drill... so may not be good, either. You could helicoil... or make your own inserts. I have to make inserts from time to time when someone already fubarred a heli coil (not our shop.... garages) and there's no material left (due to water passages nearby)

We've had to do some real ghetto fixes..... one was a 388" supercharged small block mud runner (about 900-1,00hp) and the engine builder that built it messed up wiping out the #1 main. Couldn't re-hone as the damage to only that one was bad in the block. So, I line bored it until it cleaned up, then took an old cast iron sleeve and bored/turned it then mad a "shell" that ended up bolting into the #1 main. Re line bored/honed it all and the thing has been running and racing for years now.

But as far as heli coil... maybe an insert would be best for you?

["Top Fuel" Bender]

Roll Tap has a larger hole

PDF link not working
but basically just say a 1/2-13 with a cut tap 27/64 .421875 drill size
roll/form tap 15/32 .46875
your pushing the metal back in hole to form the thread so you need a bigger hole to start with

[Directconnection]

Roll Tap has a larger hole

hahaha! Yeah, my thought process was backwards when I typed it as I was rushing to get off the computer at work (end of my 10:00am break). We used to use roll taps a LOT at the shop I used to work at. Rolled threads are much stronger than cut threads. Can't say I remember trying them in cast iron, and might not want to as cast won't form as easily.

[Turbo3Iroc]

Is there enough parent metal around to overbore and helicoil?

[Directconnection]

Krap... my post didn't go through.

I inherited a 1986 T-I Lancer ES back around 1992 that was beat and fubarred. I did a HG on it and the 11mm bolt stripped out. Installed a helicoil and it was fine..... until I went to do another HG a few years later (did I say this car was fubarred?) This time, the helicoil pulled out. So, I installed an insert that has an even larger diameter. I can't say a helicoil for a 1/2" stud would leave much material... but I'd investigate for sure.

[lengel]

Ok guys this is what I came up with. First pic is the fixture(fixture has some extra holes in it it was a scrap piece of metal floating around the shop), hardware, taps, drill guide, tap guide, and 1/2 stud kit. 2nd pic is the fixture mounted to the block with the drill guide mounted in the first hole. The fixture uses the block pins to ensure all the hole line up perfect. 3rd pic is the tap guide. 4th pic is 1/2 bolt hold down in the first hole and drill guide in the 2nd hole. If anyone is interested in upgrading to 1/2 stud let me know I would let anyone use this fixture.

[turbo2point2]

Nicely done! A great solution for someone who doesn't have access to a mill or to do the conversion in car

["Top Fuel" Bender]

Very Sweet !

[black86glhs]

I so could have used this!!!! Nice.

[BadAssPerformance]

Awesome!

[lengel]

Had to post this pic of the new 1/2" stud next to the old 11mm stud!

[Shadowv4l]

Thank God I live in PA, we got all teh brainz