Valve adjustment?

[frankiee]

Is it better to set the valve lash ajustment on mechanical lifter design engine with the engine warm and off or actually running at operating temperature?
Overlook the inconvenience of oil throwing around.

 

[MikeHalloran]

Off, and stone cold.



Mike Halloran
Pembroke Pines, FL, USA

 

[JimCasey]

If it is an unmodified production engine, the specs are usually for off and stone cold as Mike said. If you have a modified engine, there is the possibility that various pieces have different thermal expansion rates than the stock parts. Then you warm up the engine thoroughly and set the gap with everything hot. On a race engine you can set a very small gap to ensure that the valves open as much as possible. You just want to make sure that no matter what the gap never goes negative, becausr then you would be holding the valves open with immediate and severe detriment to performance. Your reference to Setting the valves with the engine running and oil slinging everywhere is done on Chevy V-8s with hydraulic lifters and rocker arms with ball studs, but I can't see how you'd get accurate clearances with mechanical lifters and the pieces thrashing about.

 

[MikeHalloran]

I've set 'em on a running engine. It's easier if the engine idles real slow.



Mike Halloran
Pembroke Pines, FL, USA

 

[sterl]

The race car guys set them running at least the first few times, to establish what the gap needs to be for their A-Market valve train...Pretty easy actually on a running V-8. Pull the Plug Wires on the cylinder of interest and at least one adjacent in the firing order. Place feelers in gap until one is selected that will just move around when the valve is in the lash position...Should be able to tell easily by engine response and adjacent cylinder "burbling" if valve under test is offseating or not. Rev the engine under lead a little bit with feeler in place, if it bucks on accel, the clearance is too tight, back off at least one. Continue until the bucking stops.

Establish thereby what works for the gap. Shut off engine, cool down, add oil, measure gap "cold" on the "test" cylinder, set the rest to the same cold gap.

Oh, and don't mix up plug wires in between...