howto Adjusting valve lash

[nateo]

Ok, so as many of you know I've been having trouble getting motor to idle properly all summer. I have taken it to two different shops now both have charged me $300 and still haven't fixed it yet.

I had to r&r port head before this trouble began. I'm confomertable with all steps involved in this (adjusting in proper order starting with tdc compression stroke, etc.) except finding zero lash. The method I used was I tightened until just before I could not spin the rod then went half of a turn. Did I go to far? I've read some articles that say to get oil deflectors and then adjust with engine running. Is this a more fool proof way of doing the adjustment?

 

[ojotaylor]

I had to adjust a few of mine (5.7) with the engine e running. This was done after I set each individually starting with #1 then following the firing order. I only had two that were still a bit loose. Talked to my dad about it. He's an old school mechanic and said that's how they use to do the older model 350's. Mine is as quiet ad can be now. Sounds like your timing may be off a hair or you may need to adjust the idle adjustment screw and/or the fuel adjustment screws on the front of the carb - if it's a carb'd engine. I haven't read any of you other posts.

 

[alldodge]

Ok, so as many of you know I've been having trouble getting motor to idle properly all summer. I have taken it to two different shops now both have charged me $300 and still haven't fixed it yet.

I had to r&r port head before this trouble began. I'm confomertable with all steps involved in this (adjusting in proper order starting with tdc compression stroke, etc.) except finding zero lash. The method I used was I tightened until just before I could not spin the rod then went half of a turn. Did I go to far? I've read some articles that say to get oil deflectors and then adjust with engine running. Is this a more fool proof way of doing the adjustment?

Yes you probably went to far, for a stopped engine. With engine stopped and everything well oiled, valves at TDC for given piston, loosen rocker nut until you have plenty of up and down play. You want to make sure your lifter has come back up. Now tighten slowly down while turning the push rod "and" moving it up/down. The up/down movement is what your feeling for not the turning. Once the up/down play is gone stop, then tighten one additional turn.

I still like doing valve adjustment with engine running

http://boatinfo.no/lib/mercruiser/manuals/mercruiser9.html#/168

 

[nateo]

Yes you probably went to far, for a stopped engine. With engine stopped and everything well oiled, valves at TDC for given piston, loosen rocker nut until you have plenty of up and down play. You want to make sure your lifter has come back up. Now tighten slowly down while turning the push rod "and" moving it up/down. The up/down movement is what your feeling for not the turning. Once the up/down play is gone stop, then tighten one additional turn.

I still like doing valve adjustment with engine running

http://boatinfo.no/lib/mercruiser/manuals/mercruiser9.html#/168

thanks for link and info. Do the oil deflectors you mentioned in previous post really keep the oil from going everywhere?

 

[alldodge]

thanks for link and info. Do the oil deflectors you mentioned in previous post really keep the oil from going everywhere?

If you say I did, I guess so but sure don't remember saying the oil wouldn't go everywhere. It will splash, will need to put rags over everything you can, oil doesn't go far just makes a slight mess. Not like it will be a gusher, just sprinkles

 

[Bondo]

Now tighten slowly down while turning the push rod "and" moving it up/down. The up/down movement is what your feeling for not the turning. Once the up/down play is gone stop, then tighten one additional turn.

It will splash, will need to put rags over everything you can, oil doesn't go far just makes a slight mess. Not like it will be a gusher, just sprinkles

Ayuh,..... I hate those write ups that always say turn the push-rod,.....

It's the up/ down movement yer lookin' at,.... turnin' it is irrelevant,...

Doin' it runnin' is abit messy, but I don't have a set of the clips either,...
Only seen 'em once,... as an early teen, I hung out at my neighbor's auto repair shop,.... back in the '60s,....

 

[Grub54891]

I have the clips, about 10 bucks 20 years ago. They do help oil from squirting all over, but rags are a must. My son made a set of valve covers, cut them out just enough to adjust the lifters, no mess no fuss. Just put them on and replace when done.

 

[Silvertip]

Clips are not as good as using heavy duty aluminum foil folded tightly around the push rod end of the rocker arm. That and laying a rag over the other rockers will help keep the mess to a minimum. Another trick is to head to a bone yard and buy a rocker cover. Cut the area above the adjustment nuts just wide enough to get the socket through. Now lay a rag over the rockers not being adjusted and you have practically no mess. The running method is still the best method in my view and I am older than dirt. I've done it both ways since the small block was born.

 

[nateo]

ok, so I cut hole in valve cover today and have one side adjusted. About to do the other. Now I counted and it did appear to be about 3 turns loosing before the clatter started so I figure I was about 2.5 turns from zero lash. This wasn't what I was hoping. Thinking valve adjustment might not be my problem. I did however discover that valve cover gasket was not seated properly and was leaking. Would that likely cause vacuum leak?

 

[alldodge]

Valve cover has no connection with vacuum. If can be spewing oil and will not effect vacuum. All vacuum is produced by the pistons, valves, intake and carb/throttle body

 

[biggjimm]

If you backed the rocker nuts off 3 full turns before you got any chatter out of them, they were too tight & would cause it to run rough at idle.

Most people I know don't have the "feel" to set them while the engine is not running. Mostly because as Alldodge & Bondo pointed out, they are turning the push rod rather than feeling the up/down movement of the push rod in the rocker.

I can set them either way but still prefer doing it while running the engine. I've got the old valve covers I cut up years ago & that definitely helps with the oil mess but you still get some splash.

You should get her smoothed out & idling nicely now. Good luck. Jim.

 

[FreeBeeTony]

I would adjust the lash w/o the engine running. .....w/ each piston at TDC.
Tighten the nut till the up/down movement of the push rod is removed....then tighten another 1/4 turn.