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Torque is 65-70 foot pounds. If your installing the head, you should put assembly lube on the washers that go under the head bolts. Bolts should be new, not reused. Put thread sealer on the threads since they go into the block water jacket.
I believe that 91N*m or 67 lbsft is the most frequently discussed numbers for the head bolts.
I'm guessing you're wanting to know rocker adjustment and that's been discussed recently with several points of interest. I didn't stumble upon the thread easily but I believe WW started the thread by asking so I'd think he'll be by soon and point you to the discussion. It was interesting I'd think a "good read".
If your really asking about how to adjust the valves and not clearance.....here are the details to adjust the valves:
Adjusting valves on the 1985 Corvette or a L98 engine:
1) Remove the spark plugs. This makes it much easier to turn the engine by hand.
2) I believe that the nut in the center of the bottom pulley on the balancer is 5/8”. Use a six point 5/8” socket to turn the engine over by hand to line up the timing marks. Place a finger in the spark plug hole for plug #1 as you turn the engine over. You are trying to determine if the engine is on compression as you line up the marks. If you feel the air pushing against your finger as you line up the marks, you have compression in cylinder #1. Align the timing marks. I have found that the slot on the balancer is often hard to see if the engine is running and you have a timing light attached trying to set the timing. This is the time to clean the groove in the balancer and use something like paper white out or a little white paint in the groove. Makes the timing job much easier.
3) Loosen all the lock nuts in the center of the rocker arm 4-5 turns.
The exhaust valves in the SBC Head are right next to each other for the 2nd and 3rd cylinders back. So if you were to start at the front of the engine the layout of the valves would be: ext, int int, ext ext, int int, ext
4) Now adjust the valves as follows:
Intake #1, 2, 5 and 7 then adjust Exhaust 1, 3, 4 and 8.
Note: If you are not sure which valve is the intake and which is the exhaust, look down at the exhaust manifold. The exhaust valve will be right above the exhaust pipe for the cylinder you are looking at.
5) Turn the engine 360 degrees (one full turn) and line up the timing marks again. Now adjust the following:
Intake 3, 4, 6 and 8 then adjust Exhaust 2, 5, 6 and 7.
You are now finished with your adjustment. I usually tighten the lock nut 3/4 turn after adjusting to zero lash.
If you are adjusting roller rockers with a locking Allan nut inside the nut, turn the adjusting nut about 1/2 of a turn and then tighten your Allan screw. Now turn the nut and the Allan screw at the same time the additional 1/4 turn. This will lock them tight.
Once you have adjusted the valves, it is likely that one or two that you have adjusted have loosed up a little and you will find a little slop between the rocker arm and the pushrod. DO NOT re-adjust. What has happened is that the lifter has bled down a little. If you re-adjust at this point, once the engine is running and the lifter has pumped up to full again, the valve will be too tight and be partially open as the engine runs. The engine will run rough…so don’t do it!
Here is a alternative to spinning the push rod between your fingers (from Forum member JoeC) that I have found works great:
BTW, I tried something a little unconventional on adjusting hydraulic lifters. One thing that always bothered me is the statement "spin the pushrod until resistance is felt" that seems a little too subjective to me. So I tried this: I set "zero" lash with a .0015" feeler gauge while slowly turning the adjusting nut. {place the feeler gauge between the top of the valve stem and the rocker arm and pull on the gauge slowly as you tighten the nut.} When I felt the feeler gauge grab, I was fairly confident I was about .001 from zero lash. At that point, I turned the adjusting nut 3/4 turn. I recently read that one turn is equivalent to .040" because of the thread pitch on the threaded rocker arm stud, so 3/4 turn should give you about .030" adjustment. I also read that within a hydraulic lifter there is .060 total plunger movement, and ideally you want to be just about in the middle of that range, or .030 inch. I don't know if I’m out in left field on what I did, but I feel I got a really consistent valve adjustment across the board. if you think you might have a tight cylinder, maybe give this a try - it seemed to work for me...
Thanks for the info!
I use arp bolts, then you use 70 lbsft i think?
Is there a difference for the little bolts and the big bolts for torque specifications?
you need to do it in 3 steps?
All the bolts torque to the same 65-70 pounds. First be sure to put the thread sealer on the threads of each bolt....have the washer on the bolt first. Then take some assembly lube and put some of this between the head and the washer. Then put some lube under the washer where it will contact the head. Hand thread into head. Then start your torques sequence per the above drawing.
I am old fashioned and would torque the head bolts to about 45 and then increase in 5 pound steps. Just me. I felt that it put a more even pressure on the gasket all the way around as I slowly built up to the torque value of 65 pounds. I usually torqued to this value.
10-06-2015, 09:59 AM
Cylinder head bolts torque specifications+Valve clearances
