Strange problem with head install
01-07-2004, 01:31 PM
#1
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Strange problem with head install My buddy and I installed some stage2 heads onto my engine the other day. When we fired it up we heard some clacking (of the lifters?), but we shut her down when the noise continued to occur even after the coolant had reached operating temp. We decided to take off the valve covers and double check the torque readings of the rockers. When we retorqued the rockers, we noticed that both intake and exhaust valves were being opened (on the same cylinder) as we tightened the rockers. The valve that was supposed to be closed would eventually be pulled shut after approx. a minute by the valvespring. What is the deal???
We took the rockers off again and squirted oil down a pushrod, and we tightened it down again. This time it did not compress to open the valve rather it stayed shut like it is supposed to. Did we just not run the engine long enough for it to get oil up through the lifters? Has anyone ever seen valve behavior like this with possible 'sticky' lifters when there is no oil in them?
Any advice is greatly appreciated.
We took the rockers off again and squirted oil down a pushrod, and we tightened it down again. This time it did not compress to open the valve rather it stayed shut like it is supposed to. Did we just not run the engine long enough for it to get oil up through the lifters? Has anyone ever seen valve behavior like this with possible 'sticky' lifters when there is no oil in them?
Any advice is greatly appreciated.
01-07-2004, 02:57 PM
#2
It looks like you under-tightened the rockers the first time around, allowing the affected lifter(s) to overextend. This accounts for the noise and the temporary valve opening during re-torquing of the rockers.
There are several procedures around that give options for torquing rockers to get them right the first time around, I went with old faithful...brought #1 cyl to TDC firing, tightened both rockers to 22 lb/ft, then moved onto the next cyl and so on. When all 8 were done, I gave the engine two full rotations and re-checked all at 22 lb/ft.
Basically between the ~300# valvespring and the lifter full of oil, 22# of torque won't get the rocker into place. Rotating the engine allows the valvesprings to act on the pressurized lifters and bleed them down a bit, allowing your 22# of torque to put the rocker in the right place.
There are several procedures around that give options for torquing rockers to get them right the first time around, I went with old faithful...brought #1 cyl to TDC firing, tightened both rockers to 22 lb/ft, then moved onto the next cyl and so on. When all 8 were done, I gave the engine two full rotations and re-checked all at 22 lb/ft.
Basically between the ~300# valvespring and the lifter full of oil, 22# of torque won't get the rocker into place. Rotating the engine allows the valvesprings to act on the pressurized lifters and bleed them down a bit, allowing your 22# of torque to put the rocker in the right place.
