What are the results of leaving valves un-adjusted for a long period of time ?

[Chad535]

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[George M]

depends whether they are set too tight or loose for a prolonged period. Always best to err a bit on the loose versus tight side....mostly for heat transfer...will also marginally decrease overlap and modestly diminish absolute lift. Visualize a loose valve as the lobe goes whirling into the eccentric and the valve gets lifted a bit later and higher up on the lobe in essence doing a bit less work...and getting off the lobe a tad sooner.
I generally run my valves on my M-30 about a slip .013" both intake and exhaust set cold. It is rare to burn a valve on an M-30 even set too tight...but generally the same amount tight as loose is worse case scenario. It is also a fallacy that valves just become loose over time...they can tighten a bit as well.
HTH,
George

[Chad535]

Well .... the valves in my case have not been udjusted for a long while and the ticking noise is getting louder by time. in addition an odd vibration would come on lower RPM bands (1200 - ~2500) but i don't know if this could be attributed to the valves being misadjusted.

[gale]

Adding to George's good advice, in addition to setting the proper gap, it is important on these engines to verify that the oil spray bar banjo bolts have not loosened. These engines have a history of the banjo bolts loosening with time and can often times loosen before the 15k valve adjustment interval comes about. That is the primary cause of cam lobe/rocker arm tip failures. Excessive ticking in the valve train can also be due to the front of the head starving for oil if it's not getting delivered and if yours is getting progressively louder, I would open it up as soon as possible and tend to it. Here's what can happen when the cam loses oil (compliments of "jamesbarns", roadfly):



The harmonic noise at 1200-2500 could posibly be the chain tensioner/rail? George, any comments on that? I know the m30 is pretty reliable in that area. How many miles on your engine Chad?

[George M]

Hi Don....
the tensioner can go slack on these engines...the piston losing its prime for a couple of reasons. Best to check the level of chain tension when you have the valve cover off with a long blade screwdriver. The chain should be relatively taut. I actually got to know Jamesburns a.k.a. Fritz quite well. He had his head rebuilt and reassembled his M-30 with the cam out of time and bent a no. of the valves. I walked him through getting the head back on properly and am happy to report his engine is running great with no side effects...hard to kill an M-30....a terrific engine. Don't know Don if you are gonna make another run of banjo bolts modified to accommodate safety wire but I encourage all with an M-30 engine to safety wire their two banjo bolts to prevent the oil distribution bar from loosening and causing oil starvation as shown on Fritz's cam. Perhaps if sufficient demand on this board...and there should be....Don will graciously make another batch of them for a very small fee. You will not find a better job performed on these bolts period.
George