Cylinder head torque
- Thread starter barks944
- Start date
TTM
Well-known member
The wider sealing ring on the WF headgasket is only on the block side, and apart from that the headgasket is the same as a standard headgasket so I see no reason to proceed with a torquing procedure different from what's stated in the servicing manual.
For what it's worth Sly has used a metal headgasket on his rebuild and torqued the head the same. It hasn't been leaking (...yet!).
For what it's worth Sly has used a metal headgasket on his rebuild and torqued the head the same. It hasn't been leaking (...yet!).
I agree with Thom. For that sort of boost level I'd stick to stock specs. Think it's 65psi from memory. Last season we were going through h/g every 1-2 meetings. Put in new ARP headstuds and torqued to 85psi. Lasted a bit longer, say 4 maybe 5 meetings. All with Cometic h/g. Max boost was about 1.5bar.
In the manual I have there are two approaches to cylinder head gasket fitting.
The first, and earlier approach, for a Turbo is to tighten to 14 ft/lbs, then 36 ft/lbs and finally 65 ft/lbs with lightly oiled threads on the studs.
The updated approach, for M44.51/52 engines is to tighten to 15 ft/lbs, then tighten by 90 degrees and finally tighten by another 90 degrees.
Mike
White 2.7 automatic
The first, and earlier approach, for a Turbo is to tighten to 14 ft/lbs, then 36 ft/lbs and finally 65 ft/lbs with lightly oiled threads on the studs.
The updated approach, for M44.51/52 engines is to tighten to 15 ft/lbs, then tighten by 90 degrees and finally tighten by another 90 degrees.
Mike
White 2.7 automatic
bmnelsc
New member
Is there a "knuckle-buster" or "clicker" style of torque wrench for the degree method? You probably remember knuckle-busters - the torque wrenches that "let go" when the torque was reached letting you ram your fist into something hard and/or sharp or the clickers that produce a gentle clicking sound when the torque value is reached. Just wondering as those add-on style of degree dials aren't always visible when you need them.
robwright
New member
You can use the dials to gauge an amount of degrees after initial torque but in my experience, which totals to about 20 years when talking about another 90 degrees it is just as good to do it by eye. Torque is actually quite a subjective thing. One man's torque can be different to another's even with the same setting on the wrench. The best way to do it as has been standard practice on the railway for some years is to set your wrench by a torque tester. To me me this is overkill and a sign of the blame culture that we live in. I have seen some examples in some workshops of having to fill out a register after having used the torque tester.
I think this is largely affected by the amount of sustained boost you're running and quite probably the condition of your headstuds. Depending on how many times they've been re torqued could easily stretch them which under higher boost levels can lead to headlift. When this happens the cylinders vibrate just enough to create an abrasive action and it 'rubs' the headgasket away so that you lose the seal....well this is our diagnosis.
Yes, Chris, you're quite correct. Should have been ft-lbs.
bmnelsc
New member
I believe you are referring to technique here - steady pull on the wrench vs sharp tug? I've seen differences with those approaches. I'm assuming the only way you get a "correct" degree of torque value is a steady pull from the starting point until the required degrees are reached. Assuming a 90 degree requirement - it doesn't seem correct to me to go to 8o degrees and then go another 10 as you are not really stretching the bolt the same way?
Went for the two 90 degree turns method in the end. Engine is built now woo! As well as all new rings, bearings, seals etc its been balanced and the head has been ported and matched to the manifold. Dropped of my rebuilt torque tube to the body shop on saturday too! Love it when a plan comes together 
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Me neither, waiting for my test rig to be built atm. I have been working on the tuning software instead though and its looking pretty sweet. Instead of the typical excel type setup I have a full 3D render of the fuel and ignition maps and you can rotate it, drag the load sites, select multiple load sites and drag etc. Also will set it up so you can see where on the map the engine is operating and view a history of where the engine has been. Really pleased with it.
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