limits of 425 headstuds

winkdemon

winkdemon

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I have done lots of head gaskets on 6.7's never had a problem with 425's ( on a stock ish truck) but have had couple guys in the last year blow gasket again with 425's. so just wondering what you guys have for experience on the issue. I have 625's in myself but its a hard to get some people to send the extra money.

Thanks :Cheer:
 
I have a buddy with 425s and had atleast one maybe two failures(can't remember now), only running a programmer/fully deleted and is a pavement princess
 
most issues ive seen have been on deleted truck with stock turbos
 
khales said:
most issues ive seen have been on deleted truck with stock turbos
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This. Tuning plays a huge roll with the stock turbos. A lot of tunes have the drive pressure through the roof.
 
How tight are you torquing them? I run ARP 2000s (425) to 155 ft Lbs never had a failure or had a broken stud, I run 625s to 185 ft Lbs
 
Justappumped24v said:
How tight are you torquing them? I run ARP 2000s (425) to 155 ft Lbs never had a failure or had a broken stud, I run 625s to 185 ft Lbs
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Holy ****! Are you sure your torque wrench is accurate? I've never seen 12mm 425's take 155 ft lbs, and I have seen a couple break at ~135.

And 185 on the 625's. Has anyone pulled the threads out of the block getting up that high? I could see you getting close to that.
 
CorneliusRox said:
Holy ****! Are you sure your torque wrench is accurate? I've never seen 12mm 425's take 155 ft lbs, and I have seen a couple break at ~135.

And 185 on the 625's. Has anyone pulled the threads out of the block getting up that high? I could see you getting close to that.
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^^seen the same. i get leary putting them at 130. depends on the truck and what its going to be used for seen alot of 425s fail on cr. but i've also seen 425s handle well over 100psi with a s475 being the small charger in the compounds, but thats a mechanical engine. bottom line, i do not recommend 425s on cr, if the goal is adequate hp.
 
I'm not the best person to chime in, but I will anyway. My personal preference is new Cummins head bolts to ~ 130 ft lbs, unless they'll spend the money to get 625's. I've just heard of way too many CR trucks popping gaskets with 425's.


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Ive got 425's on my 2011 for 5 years no issues. On my 2001 10.90 truck has 8 year old 425s also that have been reused and torqued countless times. Head is oringed. That engine has seen twins with unknown drive pressure (100psi gauge) now just a single with nitrous. Both sets torqued to the recomended 125 ft lbs

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Justappumped24v said:
How tight are you torquing them? I run ARP 2000s (425) to 155 ft Lbs never had a failure or had a broken stud, I run 625s to 185 ft Lbs
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I have done the same for 15 years with no problems, except I torque the 625's to 175!
 
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I've been hesitant to tell what I've been getting away with with my 425s. They were in the truck when I bought it. My old turbo I'd hit 42 psi or so with 50+ psi DP. My new turbo I'll hit 53 with unknown back pressure (i haven't checked DP since I swapped to this one). I usually get on it at least a couple times a week and always run in my highest setting with my efi live
 
I go 170 on my 625s no problems here. I put 60psi on my s482 5000rpm no head gasket issues yet. (Knock on wood because sh!t happens haha)
 
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