It all is relavent to our out-of-adjustment it currently is. The further off it is now, the better the improvement once you correctly set it.Realistically, I expect about a half to three quarters mpg increase when I set mine, every 200,00 or so.
what changes in an overhead that makes it necessary to do an overhead or valve adjustment? How often should one be done?
you have a specified amount of valve clearance between the valve and the rocker arm. As the engine wears, the clearance goes away. This effects your cylinder timing. The BIGGER danger comes from NOT resetting the clearance and you have a situation where you have NO clearance. When that happens, the valves are held ever so slightly open and you burn the valve and/or valve seat. Basically ruining the head or valves. The repair is then to have a new head installed or get a valve job done. Simple way to avoid that, just get the over head ran every 12-18 months.
I do my own overhead and totally know about the valve clearances but as these would wear, it would not cause a no clearance situation but more clearance which would only hold the valve open longer. But from what the machine shops tell me, these valves would only wear maybe 2 thousands in a million miles and there is more tolarance in the adjustments than that. I do adjustment and or check mine atleast every year. Mostly because that has been what I've been taught. But I rarely find them out of adjustments. Lets not forget the injector timing adjustment.
my DD S60 was loosing clearance and after finding three valves at less than 0.004" clearance, he quit checking them.
because instead of getting an actual reading, he just went and set them to spec. And they were all a long way off.
Thanks for the responses.....will be getting mine done soon. The tolerances are very close on this motor, .002 intake and 1.6 exhaust. I would do it my self but Volvo uses shims on the exhaust and I don't feel comfortable with it
