valve adjustment/ clearance

[fj11.5]

hey all, just had a look at the head ive got for the fj,   all the valves are opening is that an indication that the shims are at least close to being ok, the valves seem to come out of the head at least 10mm or more 

[Pat Conlon]

No. Valve opening is not the issue. Valve closing is the issue, or lack of closing, is the issue.

As the valve ages it erodes and sits deeper in the seat, thus the valve stem gets longer resulting in the shim/cam clearence getting tighter. To a point where the valve can not fully close and then leaks white hot combustion gasses and thus burns the valve seat and the valve itself. Major headache. Typically the exhaust valve.

Sure, if the valve does not fully open you will get a reduction in power but, the motor will run.
If the valve does not fully close...bad things happen.

[fj11.5]

thanks pat, thats just the info i was after, , also the reason  im going to change heads as #4 exhaust valve /seat is trashed, didnt get the shims done  as i needed to get to work, good ol catch 22 only found the problem after i had the shims sorted out, mechanic said it may have a burnt valve at the time, 

[SlowOldGuy]

If you've got the cams on the head, then go ahead and measure the valve clearances. 

When I replaced my valves, I bolted up the cams and made all the measurements and adjustments on the bench.

DavidR.

[racerrad8]

If you've got the cams on the head, then go ahead and measure the valve clearances. 

Only one cam at a time or you will bent some of the valves when you are turning the cam around.

Take out the second cam while you are checking the other. The 5.5mm valve stem can be bent by hand, so contact between the intake & exhaust valves bends them everytime...

I did that once, one my first engine back in '94...BTDT


Randy - RPM

[fj11.5]

thanks randy thats good  info to know, glad i didnt attempt to  check both at once, never thought of them touching,   ,, slow guy , yes  have it sitting on the bench, all i have to do now is remember where i hid the feeler gauge over the last few months .at least checking clearances on the bench i cant drop anything into the depths of the engine