[Mr. Gabo]

1995 civic dx
D15b7 with D16z6 head
Chipped p28
Aem cam gear.
I did the mini me swap about 5-6 months ago and since then I've had to readjust valve lash like 4 times. It seems like every couple of weeks rpms tend to break up at like 5500-6000. However it clears right up with a valve lash adjustment. I'm following the correct procedure, I'm using the correct specs for the factory cam, but for some weird reason it keeps loosing adjustment. Am I not tightening the tappets enough? Over tightening? Or is there something else going on?

 

[mattliston]

first, if worried about over or under tightening, I have been fine with simply snugging up the nut, and giving it ever so slightly more. Kinda like a gasketless sparkplug. Then re-checking gap after you finish tightening it.

second, as the valve seats wear out, the lash adjustment gets tighter.

Try redoing the lash, this time hanging out in the upper service adjustment level. If it specs 0.007-0.009" on the intake, shoot for a 9 fitting, but a 10 unable to fit. an 8 would feel ever so slight amount of drag.

same thign with exhaust side.


Another thing that might be worth checking out, check how all the valve springs are sitting. ANy of them noticabley lower or higher than another when the camshaft is removed? or out of line? Perhaps you have a bent valve somewhere, or springs that are worn out and much softer than spec.

valve float can certainly shake things up and knock it out of adjustment.


Heck, maybe it is as simple as the valve seats are dirt as hell, and the extra driving time is wearing down the buildup. Ive seen some D series pull a compression test 60-80 psi down in a cylinder, and a quick valve lapping during a head gasket change fixed it right up after finding no other damage or signs/reasons.

 

[Mr. Gabo]

Before I swapped the head I had it milled and vacuum tested. Dudes at the machine shop said the weakest hole held 21inhg so everything is sealing ok. After each time I readjust it runs great for a few weeks then seemingly out of nowhere it starts to break up untill I adjust valves again. Next time I have the valve cover off I'll see what the springs look like.

 

[mattliston]

when you make your adjsutments, are you having to tighten or loosen the lash?


try to use your feeler gauges to measure where they are actually at BEFORE touching the adjustment.

Maybe it is time to see what a fresh-ish set of adjustment studs from another motor does.

Also check the tappets/bottoms of the adjsutment studs. Maybe they are wearing right the hell out!!