ARP head studs revisted
05-12-2006, 12:04 PM
#31
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Originally Posted by HOHN
JWI? Just Walked In?
It's my personal feeling that most HG failures are from improper prep. So what if the truck has O-rings? If it isn't machined perfectly flat, can you expect it to seal? What if the head is decked but the locating dowel holes aren't drilled deeper? The dowels will cause the head to sit up, and you'll blow the gasket no matter how much torque you have on those monster studs!
BTW-- does a 5.9 have head locating dowels? I've never had mine off (nor do I plan to until I port the thing).
The other thing that, imho, would help is cryo tempering. A long casting like the exhaust manifold and the cylinder head warps easily from uneven heating. The cryo tempering eliminates that potential warpage.
I know of cases were a whole engine was removed from a vehicle, cryoed, then reinstalled-- all without disassembling it in any way.
The amazing thing was that the engine gained 20hp! Who knows why-- valve train harmonics, piston stability, valve sealing. The cryo temper only helps, it can't hurt.
You CANNOT skimp on head prep. It needs to be up to temp (200+) when being decked. I'll stop here, as I'd end up repeating my previous rant in the "good news, bad news" thread Don started.
Justin
It's my personal feeling that most HG failures are from improper prep. So what if the truck has O-rings? If it isn't machined perfectly flat, can you expect it to seal? What if the head is decked but the locating dowel holes aren't drilled deeper? The dowels will cause the head to sit up, and you'll blow the gasket no matter how much torque you have on those monster studs!
BTW-- does a 5.9 have head locating dowels? I've never had mine off (nor do I plan to until I port the thing).
The other thing that, imho, would help is cryo tempering. A long casting like the exhaust manifold and the cylinder head warps easily from uneven heating. The cryo tempering eliminates that potential warpage.
I know of cases were a whole engine was removed from a vehicle, cryoed, then reinstalled-- all without disassembling it in any way.
The amazing thing was that the engine gained 20hp! Who knows why-- valve train harmonics, piston stability, valve sealing. The cryo temper only helps, it can't hurt.
You CANNOT skimp on head prep. It needs to be up to temp (200+) when being decked. I'll stop here, as I'd end up repeating my previous rant in the "good news, bad news" thread Don started.
Justin
Since I am kinda thinking along these lines, I have alot of interest in what you are saying, and therefore some questions:
What is the consensis on the effects of cryo on cast iron? I have heard it helps such items as brake rotors, and then I listen to a welder/metalurgist friend who says "no effect and waste of money".
Also, if you were to drop the entire engine that near to absolute zero, what have you done to the seals?!?
Before going any further, I want to express my deep-hearted thanks to both you and Don for sharing some hard -earned knowledge. You guys are great. I have never dealt with Don, but am more impressed everytime I read a post by him.
On the ARP studs....I have used their rod bolts for years, and couldn't be happier with them, but have not used their studs yet. What is the problem with their length, and as asked elswhere, CAN they be installed without removing the head? What is involved in bottom tapping, especially with the head intact, and what kind of money are we talking?
Again.....You guys are the BEST!
Thank you kindly.
05-12-2006, 02:37 PM
#33
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Originally Posted by HaulinBut
WOW.....What a Great Post!
Since I am kinda thinking along these lines, I have alot of interest in what you are saying, and therefore some questions:
What is the consensis on the effects of cryo on cast iron? I have heard it helps such items as brake rotors, and then I listen to a welder/metalurgist friend who says "no effect and waste of money".
Also, if you were to drop the entire engine that near to absolute zero, what have you done to the seals?!?
Before going any further, I want to express my deep-hearted thanks to both you and Don for sharing some hard -earned knowledge. You guys are great. I have never dealt with Don, but am more impressed everytime I read a post by him.
On the ARP studs....I have used their rod bolts for years, and couldn't be happier with them, but have not used their studs yet. What is the problem with their length, and as asked elswhere, CAN they be installed without removing the head? What is involved in bottom tapping, especially with the head intact, and what kind of money are we talking?
Again.....You guys are the BEST!
Thank you kindly.
Since I am kinda thinking along these lines, I have alot of interest in what you are saying, and therefore some questions:
What is the consensis on the effects of cryo on cast iron? I have heard it helps such items as brake rotors, and then I listen to a welder/metalurgist friend who says "no effect and waste of money".
Also, if you were to drop the entire engine that near to absolute zero, what have you done to the seals?!?
Before going any further, I want to express my deep-hearted thanks to both you and Don for sharing some hard -earned knowledge. You guys are great. I have never dealt with Don, but am more impressed everytime I read a post by him.
On the ARP studs....I have used their rod bolts for years, and couldn't be happier with them, but have not used their studs yet. What is the problem with their length, and as asked elswhere, CAN they be installed without removing the head? What is involved in bottom tapping, especially with the head intact, and what kind of money are we talking?
Again.....You guys are the BEST!
Thank you kindly.
Don is so much smarter than me in all this that it's almost an insult to him to pair his name with mine
All I do is read a lot, so don't confuse that with firsthand experience or knowledge.
I would encourage you to get "second opinions" for sure.
Anyway, back to cryo tempering. Personally, I think it's common sense that it should be done. It's not some kind of magic potion that prevents anything bad from happening, but it ALWAYS helps.
As for the seals, they are not harmed. Just don't try to start an engine that's currently near absolute zero (which cryo tempering can't do).
The question is HOW MUCH, and IS IT WORTH IT.
That's something only you can decide. I personally think that long castings subject to uneven heating benefit a lot from a cryo treat.
That said, if you have a well-seasoned head with a lot of hot-cold cycles in it, then it's probably quite stress-relieved, and there may be very little to gain from a cryo temper.
Ideally, a cryo temper would be done on the heads BEFORE they are installed on the engine when new, as THIS is when it would do the most good. I suspect it would help to reduce the tendency of 24V heads to crack across the valve seats.
The other thing you may want to consider to help the head stay even is a waterless coolant like Evans NPG+. The waterless coolant produces more consistent and even temps in the engine, and fewer "hot spots" that can exacerbate a temperature gradient and produce cracking.
EDIT: Oh, and the problem with the studs isn't the stud length, per se. It's the fact that not all CTDs have the holes drilled and threaded to the same length, as far as I know. So on some engines, the studs will bottom out sooner than on others, making it harder to install them at exactly the proper height.
JMO
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