250 Valve Adjustment

[70inline6]

Hey,

My 66 has had a sputter out of the tail pipe since I got it a couple months ago but has always seemed to run pretty good. I've never noticed any smoke from the tailpipe.

Unrelated - the valve cover gasket was toast and leaking so I needed to change that... So... I decided to check the valve adjustment since I was going to have the cover off anyway.

I warmed the motor up and then shut it off. I pulled the valve cover and made sure everything was out of the way. I started it back up and went to work....

#1 I/E required about a full turn loose to hear clacking. Tightened slowly until noise went away... then tightened about 1/2 (180) additional.
#2 I/E - same
#3 I barely needed any loosening at all before the clacking... E full turn - tightened both same as 1
#4 # 5 were about the same as #1.
#6 I was barely tight, the E took almost a turn and a half to hear clacking. Each was tightened like #1, till quiet, then about a half turn.

So now... motor seems a but quieter and tail pipe sputter has decreased, but not completely. Upon road testing, it runs down the road very well, but now I notice grey (oil) smoke on hard decel (downshifting to slow) and on heavy acceleration. It doesn't smoke just driving. Revving it while parked will produce smoke....

Did y'all think adjusting the valves cause the stem seals to fail? I've never experienced this before... what should have been a half hour and done job has me stumped a little? Opinions? Thanks.

[TJ's Chevy]

Considering how old the engine is....worn valve seals wouldn't surprise me. A little smoke isn't anything to worry about. The little sputter could be ignition or a flat cam lobe....or a burned up exhaust valve.

[Mr Bear]

I'd be more inclined to think that a little sputter at warm idle (not when running and/or at load) is an indication of lean fuel delivery at idle. (Especially if its burbling/light popping when decelerating warm in second)

New plugs and plug chop idle, mid range and WOT to see what your fuel delivery looks like at various ranges. Then adjust timing/choke/carb from there.

[70inline6]

I had a thought last night and pulled the PCV line this morning... coated in oil. So... I failed to mention that the PCV grommet into the valve cover was hard and in no way sealing anything... also, the PCV line is plumbed directly into the intake manifold, inboard of the carb adjacent to #3 & #4 Intake valves.... that's where it was when I got the truck.

I replaced the grommet and hard/cracked vacuum line to seal the circuit... but I'm thinking that is WAY too much vacuum and it was sucking raw oil right up off the #5 & #6 rocker arms...

So.. I am going to plumb the PCV into the air cleaner assy some how and cap that manifold port. That should solve the burning oil issue.

As the #6 E valve was so tight... I tend to agree with TJ... It may be burned a bit and not fully sealing any more. I'm going to run some Techron and do a full tune up and see where that leaves me. Thanks.

[Mr Bear]

For the PCV, direct manifold vacuum from the plenum below the carb or off the #3,4 runners (depending on the year of the manifold) is correct.

Before you reduce your crankcase ventilation capability to near zero with an air cleaner only set up + start drawing oil through the carb instead of under it and maybe start pushing oil past the main seals due to blow by pressures (it only takes a couple of pounds over pressure to push oil past seals, etc)...check your plugs.

If they are oil fouled you have ring or valve issue.

If not oil fouled, pull all the plugs and do a dry then wet compression test....it will indicate whether you have leakage at the rings or valves.