Anyone Tried 1/2" Head Bolts??

[BlownV6]

At this point in my journey , head gaskets/torching heads seems to be the weak link!! I am seriously looking into installing 1/2" head studs in the 2 center rows to keep the heads clamped down. Anybody eles tried this?? This is on a stage 2 block with stage 2 heads.
Mike

 

[Adam Connell]

O ring the heads.

 

[DR BOOST]

ive done 1/2" head studs in a 109 with very good results.

 

[BlownV6]

O ring the heads.

It has copper head gaskets , receiver grooves in the head and .041 SS o-ring sticking out of the block .025" . ARP Head studs all torqued to 80#.
60+ pounds of boost and heres what happens way to often
Mike

 

[daturbosix]

ive done 1/2" head studs in a 109 with very good results.

RACE CAR!

now i know your secret.

 

[BlownV6]

ive done 1/2" head studs in a 109 with very good results.

My biggest question is re-drilling and tapping the block. The 7/16 tap in block actually is a bit oversized to the drill required for the 1/2" tap. Plus going from 14 threads to 13 threads per inch!! I drilled and tapped a piece of aluminum to 7/16 then re-drilled and tapped to 1/2". You can see that the treads are not perfect but they look like it would work just fine , actually that is my ONLY concern!! Mike

 

[gnxtc2]

Before you go drilling the heads and tapping the block to 1/2", I would call ARP and try one their exotic metal studs, ie: L19 or Custom Age 625 so you can increase clamping load.

Also post this in the Supercharged section on Yellowbullet.com. There is alot of racers on that board.

Billy T.
gnxtc2@aol.com

 

[BlownV6]

Before you go drilling the heads and tapping the block to 1/2", I would call ARP and try one their exotic metal studs, ie: L19 or Custom Age 625 so you can increase clamping load.

Also post this in the Supercharged section on Yellowbullet.com. There is alot of racers on that board.

Billy T.
gnxtc2@aol.com

I have been in contact with ARP. Special order Dept. is working a solution.
Pro-mod and alcohol cars with Hemi's use 5/8" on center 2 rows and 9/16 on the outer rows. These 7/16" just aint going to handle what Im willing to put to it. Its time to step up!! I was even considering 9/16" but that would have some serious interference issues. Mike

 

[Chris Hogeland]

The block need to be set up in A bridgeport and set up right to do it you cant just use A hand drill.It takes some time to set up right

 

[WHITE T]

For what it is worth, I agree with Billy.

I would check with ARP and see if they can build a set of studs in L19. This is the same material that many of the high boost import applications run.

I heard of some of the DSM (Talon, eclipse) having head gasket issues, many of the fast guys now run L19's and run BIG boost.

I am not sure.. but this might be the material they use for Diesel head studs as well. It isn't cheap, but seems to work better

 

[BlownV6]

The block need to be set up in A bridgeport and set up right to do it you cant just use A hand drill.It takes some time to set up right

Actually it will be done by hand , BUT with a very precesion made 4" thick guide plate with bushings made for all the necessary drills and taps. I use a similar plate to drill and tap the front of the block for 3/8 bolts for my crank support. I have the plate already , I have a 4.1 production block Im going to put the extra (stage 2 ) bolts in. Mike

 

[BlownV6]

For what it is worth, I agree with Billy.

I would check with ARP and see if they can build a set of studs in L19. This is the same material that many of the high boost import applications run.

I heard of some of the DSM (Talon, eclipse) having head gasket issues, many of the fast guys now run L19's and run BIG boost.

I am not sure.. but this might be the material they use for Diesel head studs as well. It isn't cheap, but seems to work better

I will check on the use of the L19 and 625 material with ARP. Im sure they wont be cheap but fixing all this damage has got to be 4x as much!! Im going for a permanent fix , as as stated before the BIG cars (motors)are all using huge studs to keep their heads on and I think that is going to be my path???
I appreciate all the input , keep it coming as its all good. Mike

 

[turbodave231]

Mike,

Is there a reason your o-ring receiver grooves are in the head versus the block? I'm thinking that the grooves in aluminum will fail before grooves in cast iron.


2X on tapping those bolt holes by hand, even with a fixture.......A CNC Machine Center would do a much better job
Dave

 

[ijames]

More fuel! More fuel! Start rich and lean it out, instead of lean and working towards rich . Hi Mike, glad to have finally met you in person in Columbus (beard, glasses, lots of questions at the end of Sunday ). The rule-of-thumb is that you need a thread depth as deep as the diameter of the fastener to achieve a thread strength equal to the yield strength of the bolt, assuming equal strength materials on both threads. In this case the stud will be probably 3-4x stronger than the cast iron so for a 1/2" stud you would need 1.5-2" of thread engagement (which is long enough that the rule-of-thumb probably isn't very accurate any more, sigh). That also means that going to a stronger 7/16" stud may not help if the thread depth in the block is becoming the limit instead of the stud material. Having less than perfect threads from the leftover 7/16" threads will make this a little weaker, so again, get all the depth you can. What kind of thread depth can you get in the block? If it's much less than an inch, which I think unlikely, I'd be concerned about thread quality, but if it's over an inch I'd say diameter trumps depth. It's been awhile since I've gone through the calcs but if you compare the 7/16 and 1/2" threads you get one less thread per inch but the spiral has a larger diameter and and the thread surface is wider so if you unwind both of them you get more contact area with the 1/2" thread and so even at the same thread engagement depth it's stronger.

Anyway, just some thoughts.

 

[BlownV6]

Mike,

Is there a reason your o-ring receiver grooves are in the head versus the block? I'm thinking that the grooves in aluminum will fail before grooves in cast iron.


2X on tapping those bolt holes by hand, even with a fixture.......A CNC Machine Center would do a much better job
Dave

Most other applications that Im aware of do it this way, however we have tossed around the idea of doing just that and putting the o-ring in the head.
The problem in my mind is that if there is going to be a failure I prefer the head because it can be fixed realatively cheaply compared to the block!!!

I also agree that sending it off to someone and having it setup on a CNC machine and getting the threads retapped would be easier on me , BUT Im assuming that the cost of getting that would pay for the plate , taps , guides
it going to take to do this. I have 3 other blocks already sitting here fully machined. Pretty sure Im more than capable of doing this with very little difference in the finished thread quality. Another problem thats going to rear its head is the fact that the block is completely filled to the deck with concrete. I will have to get in there with a masonary bit and make a bit of room for the tap to go thru the deck. Mike

 

[BlownV6]

More fuel! More fuel! Start rich and lean it out, instead of lean and working towards rich . Hi Mike, glad to have finally met you in person in Columbus (beard, glasses, lots of questions at the end of Sunday ). The rule-of-thumb is that you need a thread depth as deep as the diameter of the fastener to achieve a thread strength equal to the yield strength of the bolt, assuming equal strength materials on both threads. In this case the stud will be probably 3-4x stronger than the cast iron so for a 1/2" stud you would need 1.5-2" of thread engagement (which is long enough that the rule-of-thumb probably isn't very accurate any more, sigh). That also means that going to a stronger 7/16" stud may not help if the thread depth in the block is becoming the limit instead of the stud material. Having less than perfect threads from the leftover 7/16" threads will make this a little weaker, so again, get all the depth you can. What kind of thread depth can you get in the block? If it's much less than an inch, which I think unlikely, I'd be concerned about thread quality, but if it's over an inch I'd say diameter trumps depth. It's been awhile since I've gone through the calcs but if you compare the 7/16 and 1/2" threads you get one less thread per inch but the spiral has a larger diameter and and the thread surface is wider so if you unwind both of them you get more contact area with the 1/2" thread and so even at the same thread engagement depth it's stronger.

Anyway, just some thoughts.

Nice to meet you also!! Agree completely with the RICH,RICH part , but I dont have that totally figured out just yet. Reguardless , the deck is approx. 3/4" thick and goes into water in the bolt holes in question , so thats what I have to deal with. Mike

 

[BlownV6]

ive done 1/2" head studs in a 109 with very good results.

Did you do this yourself or have it done??? BTW thanks for owning up to that,I relize that this is TOP SECRET SH_T !!! But I will gladly pass the info on to others. Mike

 

[DR BOOST]

i had a local machine shop retap the block. i took it upon myself to redrill the gn1's and the gasket using a power drill.

as for your poblem mike, please check with the stud manufacturer about torque specs. i have heard that you actually get more clamping force slightly under the torque specs than over it. studs tend to turn elastic when stretched.

 

[BlownV6]

I will pretty much go with what ARP says on these. Technology on this subject has probably come leaps and bounds in the past 10 or so years. Being an oldtimer Im just not quite up to speed!!! Thanks for your input. Mike

 

[gnxtc2]

Go on ARP's site ARP | The Official Website of Automotive Racing Products There is a ton of info there about different fastener metals.

L19 is used for diesel applications.

Billy T.
gnxtc2@aol.com