Knocking m42 valvetrain

[Simon S]

OK - think I'm getting somewhere now..

The sprockets with chain do fit on cams.
Initially, by moving one tooth on intake sprocket, excess chain length resulted between intake and crank sprockets (crank locked at tdc)

Excess in that section prevented sprockets from going on..


edit: Not the case. chain was possibly resting on lip of a chain guide(?)

[ck_taft325is]

I wont advise that. But in all honesty, I removed my sprockets from the chain on my S50 top end rebuild. I have 6,000 miles on it since. Same story, really rough, noisy slapping noises on start and for the first, I don't know, 45 miles? I nearly shat myself for a good 35 minutes while I scurried around the bay making sure everything was tight with a buddy (Luke) on the phone blathering about how I think I fucked up.

Deep breaths. "Don't fuckin' panic..." as Luke told me and go through it nice and slow. Again, I don't advise removing the zip ties but, I did and things are okay. That's not sound advice ;)

[Simon S]

Nope - not enough room to do that with top case on.

[Simon S]

Maybe I should count links, cut zipties, remove chain from sprokets, get sprockets on cams, then put chain on..

[Simon S]

Recap:

Prior owner had intake sprocket one tooth off. Sprocket slots were set at extreme in order to 'compensate'.

Because - when in doubt - I put things back how I found them. it didn't register to me that chain was off.

in the mean time, I thought lifters were causing the noise.

After cleaning lifters, correcting chain position on intake sprocket, and putting cams back in - now I'm having trouble getting sprockets back on cam ends.

Valve cover is off and tensioner is out.

[Dj Buttchug]

I usually loosen the cam gears so they move while still on the cam. You can grab a tiny bit of extra that way but you have to make sure you align everything right or else you can be off a tooth or so.

your trying to get the timing chain over the cam gears correct?

[Simon S]

Yeah - I pulled the cams to examine lifters.

[Dj Buttchug]

wait im confused... you pulled the gears off the cams?

[Simon S]

Any tips or ideas?

Getting cam sprockets on the ends of cams is really giving me a hard time.

Been at it for hours now..

[Simon S]

Son of a bitch !

W/ tensioner out and cams in - I can slip one cam sprocket on - or the other.

There just doesn't seem to be enough play in the chain to get them both on.

Jesus, I just need one f'ing millimeter..

[dude8383]

Awesome :)

Good call on letting them soak overnight.

[Simon S]

Ug. Just got done flushing all 16 lifters..
If you swirl them in gas - and blow compressed air in orifice long enough, lifter piston will get a nice, smooth action to it. (they were 'gummy' when I started)

But yeah, I'm pretty sure it was one tooth off on intake sprocket the whole time.

Going to head home now for sleep while lifters soak in oil overnight..

[JakeP]

Beginning to wonder if prior owner/mechanic had set cam sprocket slots at their extreme in order to compensate for being one tooth off..

This.

I'm glad the links may have helped. I have been reading everything I can find on M42 in my spare time, and remembered posts on this same topic.

Easy thing to do: set the sprockets back to both extremes like it was before the teardown. If that fixes the problem, take the chain off and reset the sprockets.

After that, Why not put the exhaust cam to stock position and intake to 6*?

[Simon S]

Don't have the tool - but it's becoming more obvious that it is the timing.

Exhaust cam 'square' is parallel. Intake is not.

Jesus, I'm glad I'm in there now fixing w/e f'ed up setting was done by prior owner.

Will keep reporting as this goes on..

[Ryann]

^Good idea. One quick glance at the square ends of the cams would tell you the story.