BILTIT

I know this has been talked about and i have read many threads on it but it seems there is so many different views on how to do this.

At what point should a person re-torque the head? I am hitting 39psi now so i figure i should do it soon.

Do i loosen one at a time and re-torque higher or just try and torque while still tight?

I don't want to do head studs yet, when i do i will be doing a bunch of head work as well. Hoping that day is a year away at least.

dieselJon

One way is to get a head bolt stretch gauge, pull 1 at a time, check, re torque.

Personally, i would by all new ones. 150 for the set.

Torque by Cummins standard up to the 90° step. Then go 10 lbs increments to 115 lbs, then 5 lbs to 135-140 lbs, waiting an hour between torques. I believe Jeff Garmon does this in his 1/2 ton swaps.

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schamran

I have heard you can go as high as 150 pounds, and yes purchasing a new set would be cheap insurance. I broke one of mine once. I got lucky and didn't have to remove the head to remove the bolt.

Onemoparnut

I retorqued my head about a year ato to 125 and it has been fine.

taterfarm

Bill, was that the original head gasket and did you pull the bolts and clean them or just re-torque?



I was hoping for more discussion on this subject, there are lots of posts on individual situations but doesnt seem to be any clear consensus on when a re-torque is acceptable and what benefits it can provide.



To add to the question of when one should re-torque I would like to know what the thoughts are on situations that are suitable for re-torquing:



And to go off topic a little on head bolts, why do these sets cost so much, there just grade 12.9 flange bolts right? 26 flange bolts and the prices range from what $95-160 a set. Then there are these kits that have allen head bolts, not sure how that is suppose to be any better but they too are quite a bit for a set . Anywhere form $130 -250ish they claim to the best thing ever.


why not just go buy quality correct spec bolts from a decent bolt manufacturer that meet the DIN/ISO specs, surely you can get the same exact bolts for way less than half the cost from a fastenal or someplace similar?


I've been dreading the costs of doing a head gasket thinking I should go all out and plan for max future power all just because my HG weeps and studs seemed like the way go while the head is out. Now I am thinking a guy can get the HG set with new "hardware store" bolts and even a set of DAP injectors all for less than the cost of the studs alone. That along with a HE351 set for 40 lbs boost should all hold together longer than the transmission will anyways, right? .

jimbo486

Injectors, "head" bolts and a upper engine gasket set for less than $500?? I'd pass on those parts without hesitation!

For the added assurance and if in doubt, just replace the head bolts. They aren't all that expensive to buy from Cummins. I don't have my invoices handy from when I replaced my headgasket 3 years ago but I bought all new bolts. Why screw around wondering if the originals will continue to hold, even if the stretch gauge says they're within the spec'd limits? In fact, I've probably got just under $2,000 in my headgasket job. I upgraded a couple of things while in the process but I didn't cheap out on anything. I also needed new nozzles for my injectors which made for about $530 of the cost. The upper engine gasket set will run you about $230 alone. Then, buying cheap, hardware store "head" bolts and cheap injectors still puts you over the cost of studs. You know the phrase, "You get what you pay for?" You won't find a set of injectors under $400 anymore. I don't know why I felt like clarifying all this but I sure hope there was sarcasm in your post.

Back on topic.

Onemoparnut

I did not remove the head bolts I just re torqued them. Head gasket is original as far as I know. I had no leaks then and still don't now I just did it because I was running a lot of boost and it seemed like it might help the head gasket last.

BILTIT

How much boost? I will be buying some new head bolts this week, planning on removing one at a time and torque up to 90ish then once all are in i will torque final amount, whats everyone think of that?

GIT-R-DONE

I have only ever done one headgasket on my Cummins. I re-used the same bolts and put initial torque @ 100 ftp and after a couple heat cycles re-torqued them to 125ftp.

Why would you want to re-torque them after they have been set to the max torque?


My motor has roughly 400K on it and have had no issues with the headgasket.

Onemoparnut

My thought was that after years of heat cycles the gasket may have compressed some and allowed for some room to tighten the bolts some more. I torqued them to 125 ft pounds and some bolts moved a half a turn some didn't move much at all but they all moved. It was making 48 psi I have since turned the pump down some to keep it around 40.

jimbo486

FWIW, the final 90* turn on the new torque plus angle method head bolts yielded at least 125ft. lbs.

I just checked them last week after swapping injectors and replacing valve cover gaskets. I had my torque wrench at 110ft. lbs. and it popped. I didn't go any higher though.

taterfarm

After a bunch of reading on bolts and torquing I have found some interesting things. The original head bolts are a torque to turn bolt not a torque to to yield. So under normal conditions on a factory original setup then the bolts shouldn't have reached their yield point and could be reused. Of course there will be exceptions for various situations where they have elongated. Now to find the accepted procedure to test these bolts, other than the drop test?

So with a torque to turn bolt I am assuming that there is a specific number of threads and cross sectional area to put the bolt into the proper stretch zone for even holding power over time. This makes be wonder how those other socket head cap screw bolts will work over time as they too are tightened to the same factory spec as the original bolts(other than the lube spec). The larger diameter of those bolts is what they claim adds the strength and value, but wouldn't that actually provide less clamping force after several heat cycles as the bolt will not have stretched as far as a stock one and will have less return as the head settles?



I guess i was a little excited about the $10 a piece price for the long bolts at the local cummins truck center. I still believe you can find these exact spec bolts for much less from a bolt manufacturer, but we are limited on supply locations around here and the guys at the counter are not worth much, especially with metric bolts, without a part number they are lost and metric designations seem to be a foreign language to most.

Where are you guys getting stock head bolts from and is there a cummins part number for the complete set?

On the cost of the job I had a quote of $170 for a gasket set from a diesel shop, they usually have all OEM stuff so I didnt even think it may not be a cummins part, I'm guessing now that its probably not. So I'm off a little at $230 for the set. Agkits.com has head bolts for $90 a set, guess I need to see where they come from too(anyone ever used this place before?). Then that leaves the DAP injectors at $250 which I guess people here seem to like so far. but I did forget about having the head checked and resurfaced so that along with the added cost and its a over but not by that much.



Back to the re torque procedure I read the article in Diesel power and they did the re-torque both ways; just tightening the bolts and pulling them, cleaning and re-torquing. They seemed to be happy with both methods http://www.dieselpowermag.com/tech/d...o/viewall.html
It seems like removing , cleaning and oiling would be the best practice to prevent yielding the bolts, especially if wanting to see higher pressures or using old bolts. The way I read the removal method they say they removed cleaned and oiled then re-torqued in steps, I take it one bolt at a time to full torque?

Anyways, sorry if I am not helping your cause, I know you build things right from all the work on your truck. I have just been thinking that a mild build with limited boost at 40lbs or so should be fine with stock bolts, even reusing the bolts if they test out fine. hopefully someone can provide the measurement guides to actually test the bolts.

BILTIT

I just spoke with my local cummins and they do not sell a head bolt kit, you buy them individually. They tell me there is only 20 bolts and 2 sizes, i dont think that is correct so i may just purchase them elsewhere. It is difficult to find good parts people these days.

taterfarm

Ref No Part Number For-Sale Shopping Cart Part Name Required Remarks

12 3920779 Screw, Hexagon Flange Head Cap 6
13 3920780 Screw, Hexagon Flange Head Cap 14
14 3921394 Gasket, Cylinder Head 1

check out this site cummins quick serve, it lists all the engine parts by the serial number, even has build date. not sure why it only lists two bolts though, if there isnt a part number then it cant exist right! the other part number was 3920781 from agkits.com, they show 6 of them as well.
https://quickserve.cummins.com

BILTIT

Ya, but look here:

http://www.cumminsperformanceparts.com/12vhebokits.html

http://www.dieselpowermag.com/tech/d.../photo_10.html

http://abdiesels.com/forum/index.php?showtopic=3077