12mm vs 14mm head studs

Pissing match. Unless you're pulling the block for other work, machine head flat. O-ring or fire-ring head. Get genuine cummins gasket of thickness desired/needed. Buy what you feel are quality studs for your application. Install. Done.
 
It aint no pissin match here. I think Dans choices are fine for him. I dont see it his way but its cool. I like to read what other people have to say. Dan has been pullin along time so im sure he has his reasons he just need to tell them upfront so i dont have to work so hard to get them.LOL

Tim
 
I ran stock head bolts with a stock Cummins marine gasket all last year after my somewhat built engine with 14mm studs broke the cam. On that engine there was a crack coming out of one of the back holes running to a water passage.

Torqued the stock bolts to about 140 and let er eat. Running a 13mm pump, s471 turbo with a big exhaust housing, turning 4200-5300 rpm down the track, 50psi boost.

I believe that back pressure is the key factor in headgasket longevity. My 2 "Centless" .
 
Turd Ferguson said:
Pissing match. Unless you're pulling the block for other work, machine head flat. O-ring or fire-ring head. Install. Done.
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ILLINOISRAM said:
It aint no pissin match here.
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So some more background...I try not to get too specific when I start threads anymore because it seems when I do they go nowhere.

I posted this in the extreme engine tech section for a reason. This is not a "street" class build, so I do not consider the answer to my questions a "pissing match". I am looking at moderate to large compounds for my open driveline truck. The bottom line is when I get this thing together I do not want to have to pull the block back out to get machined for 14mm or 9/16" studs because 12mm studs cannot hold it down. I would much rather be fighting traction issues and fine tuning the fuel system.

Block is already at a machine shop getting checked out before I take it elsewhere to get further work done. Head has been surfaced and fire-ringed; block will be the same. I just needed some opinions on what studs to use.
 
j-rod said:
So some more background...I try not to get too specific when I start threads anymore because it seems when I do they go nowhere.

I posted this in the extreme engine tech section for a reason. This is not a "street" class build, so I do not consider the answer to my questions a "pissing match". I am looking at moderate to large compounds for my open driveline truck. The bottom line is when I get this thing together I do not want to have to pull the block back out to get machined for 14mm or 9/16" studs because 12mm studs cannot hold it down. I would much rather be fighting traction issues and fine tuning the fuel system.

Block is already at a machine shop getting checked out before I take it elsewhere to get further work done. Head has been surfaced and fire-ringed; block will be the same. I just needed some opinions on what studs to use.
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My opinion shortend,

big twins= big boost and drive pressure = .105 firerings= big studs

just my .02$
 
ILLINOISRAM said:
...big twins= big boost and drive pressure = .105 firerings= big studs.
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Quite frankly, I agree.

Just guessing on the post about finding a crack in the block, but I would have to assume the stresses seen that from the cam breaking and then letting loose were more than likely a contributing factor.
 
ILLINOISRAM said:
big twins= big boost and drive pressure = .105 firerings= big studs
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Definitely would be on the side of caution to go that route. With guys running triples on 12mm's I thought they may work with a big set of twins, but it looks like 14mm or 9/16 are going to be the better way to go.
 
j-rod said:
Definitely would be on the side of caution to go that route. With guys running triples on 12mm's I thought they may work with a big set of twins, but it looks like 14mm or 9/16 are going to be the better way to go.
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Mainly just do what you feel right with and comfortable with. You probably can get by with the 12mm if you take care of proper wastegates and drive pressure. The only blown hg i have had or seen have always been with twins other than stock motors cranked up.
 
ILLINOISRAM said:
Mainly just do what you feel right with and comfortable with. You probably can get by with the 12mm if you take care of proper wastegates and drive pressure. The only blown hg i have had or seen have always been with twins other than stock motors cranked up.
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I would imagine getting the static compression low enough would help too.
 
there are many threads on this , but the clamping load of a 625 stud is almost exactly the same as using a 14 mm studs . the block is more then capable of holding the studs with eather threads , the problem is that if you remove the material then you weaken the block significantly. this is just a fact , look at a cut away of that portion of the deck .
the clamping load of eather stud is roughly the same ,

one other aspect is that with the weaker deck, you will have a problem with maintaining bore rigidity , and combustion containment by the rings .
I do have 9/16 ARP studs for the 24 valve , the kits are $475 , and they torque to 150 ft lbs , achieving the same more clamping load then the 14 mm studs. I will not use then over the 625's , but that just from many years of engine development , and the opinion of the fasteners engineers at ARP , ( the guys that develop the fasteners that 100% of every Top Fuel engine , and 95% of NASCAR uses )
 
Big Swole said:
Technically the same thing, is it not??

Cause / Effect
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:umno:

Back pressure is created through exhaust restrictions hence putting "back" pressure to engine.

Drive pressure is created by the cylinder pressure and exhaust gases being forced out by the exhaust stroke of the pistons.
 
COMP461 said:
there are many threads on this , but the clamping load of a 625 stud is almost exactly the same as using a 14 mm studs . the block is more then capable of holding the studs with eather threads , the problem is that if you remove the material then you weaken the block significantly. this is just a fact , look at a cut away of that portion of the deck .
the clamping load of eather stud is roughly the same ,

one other aspect is that with the weaker deck, you will have a problem with maintaining bore rigidity , and combustion containment by the rings .
I do have 9/16 ARP studs for the 24 valve , the kits are $475 , and they torque to 150 ft lbs , achieving the same more clamping load then the 14 mm studs. I will not use then over the 625's , but that just from many years of engine development , and the opinion of the fasteners engineers at ARP , ( the guys that develop the fasteners that 100% of every Top Fuel engine , and 95% of NASCAR uses )
Click to expand...

:clap: :thankyou2:
 
RedPuller said:
:umno:

Back pressure is created through exhaust restrictions hence putting "back" pressure to engine.

Drive pressure is created by the cylinder pressure and exhaust gases being forced out by the exhaust stroke of the pistons.
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But if you didn't have as much Resistance (backpressure) then the drive pressure would be less, Right?

I just see it as one in the same....

Not trying to start an argument, that is just the way I explain it..

Either way, both are a bad thing when too high....Correct?
 
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