12 VALVE HEAD BOLT TORQUE
 

Correct me if I'm wrong but I haven't seen any detailed threads on re-torquing the 12 valve head bolts down to handle more boost which I'm looking into as I build up the engine a little.

Here's a good article I read online from diesel power mags you can read here on torquing the bolts down. They give 2 methods of doing it and warn the reader of torquing the bolts down more than 120 ft-lbs.

The article states the Factory Cummins torque spec is around 115 ft-lbs.
However - my Chilton manual gives the stock torque spec as
66 ft-lbs +1/4 turn for the short head bolts and 90 ft-lbs +1/4 for the long head bolts.
So....:humm:


My Question: Does anyone else have experience with this? What's the true factory specs and what specs can you push the stock bolts too?

Thanks :c:

12 VALVE HEAD BOLT TORQUE
 

I've always replaced the head bolts cause all ur gunna wind up doing is streaching them or break them. I just pulled the head off mine cause of to much boost. I'm going back with head studs and a better head gasket. Stock bolts and gasket are designed for no more than 42psi I think

i would pull one and measure it to make sure it is not stretched already. then i would re torque them to 150 if there not stretched.:tu:... or just get some studs:humm:

How much timing and boost do you want to run? :c:

@ Pyro690

40 psi

diesel power mag a few months back there is a truck built maximum diesel thats rund 600hp on twins and runs 11's with re-torqued stock head bolts torqued to 150 lbs. not saying i recommend this. just couldnt believe it when i was reading it.

...and it probably blew the headgasket the next time they started it.. haha.

The 98 FSM says to torque all bolts to 66, then torque only the long ones to 89, and then an additional 90* on all.

I would re torque to 130 if they will hold and if you can get more, go for it.

i use fel-pro head gasket print-o-seal
set torque at 100
run 35 lbs boost
in 5yrs i have blown 1 gasket
i dont see how you can run studs in the back of motor due to room the only way i can get pushrods in on #6 is to remove crossmember and let tranny hit the ground
still have to fight to get them in

there is a hole in the cal that u slip the rod in and it gives u just enough room to put it in

I would spend the money on studs. More than likely your stock head bolts are stretched. I know mine were after 140,000 and a stock turbo set at 35psi. It will save you from having to pull the head do to breaking one off in the block or stretching them and blowing the head gasket. IMO Better to be safe then sorry unless you want to spend more money on repairs than go fast goodies down the road.

Nothing against you Scott and you have done this more than myself and I know we have covered this before on here... I feel studs are overated. Yea if I had some money laying around my truck would be o-ringed and have arp 625's in it. and at minimum oring and fresh bolts. But to each his own.

No problem like you say to each his own. But if I had the money for 625's I wouldnt spend the money on o-rings

boost isn't what blows your headgasket its timing.

Theres no way that 40 psi makes a difference when your cylinder pressures for ignition
are already up in the thousands of psi

Actually, drive pressure is what blows gaskets.

Im gonna say cylinder pressure just so people have something to argue about.

lol

Nothing like stirring the pot.

look it up head torque specs per year my 94 ram 2500 cummins 5.9 sets at 135 lb.