valves out of adjustment?

[Daeron]

Pull the valve cover and inspect all your cam lobes and rocker arms for any evidence of untoward wear. In recent years there have been instances of people chewing up cam lobes and/or rocker arms for no apparent reason; the popular theory for the cause is a lack of a Zinc compound in out motor oil (zdp) which is apparently incredibly helpful at maintaining the thin boundary layer of oil between lobe and rocker surface, and most supporters of this theory throw the term "poor metallurgy" out in the same breath, regarding the camshaft. There are a couple of threads that have gone on on this subject; I cannot recall who had the problems.

 

Do you know the Screwdriver Stethoscope trick? One large screwdriver, butt the handle into your ear, and touch the tip to various points on the engine. It helps localize the type of noise you are talking about. When I do it, I sometimes go an extra hitch up and I VERY CAREFULLY push with the screwdriver handle until it sorta pinches down the ear canal, and I get a more solid transfer through into my eardrum... but obviously, on a running motor, you risk boxing the s#$% out of your ear.

 

Good luck tracking down your problem! I would definitely try to pinpoint the noise a little better before changing the timing gear out.

[eds240z]

Daeron, thanks for the info. i will difinetly do that before tearing anything apart. now, as for as this zinc theory, is there an additive? i'll do a little search on that. thanks again!!

[280zx 2by2]

Hmmm, you could just be hearing your injectors firing. Nothing wrong with that. On my 280 with brand new bosch injectors, the injectors are more more noticible at certain RPMs. For me, high idle when it's still cold. If you had timing set problems / poor valve adjustment it would get progressivly worse with higher rpms.

lol just about to say that... seeing hes gone from carbs (i assume) on the L24 to the L28e, injector tapping might be new to him...