350 sbc in my 41 poncho. Hasn't been out in months. Starts and runs with a bad miss. Checked the compression. number 1 and 8 aren't right. 90 lbs one time, zero the next, then 120, then zero. I'm thinking stuck lifters. Agreed? Any "best" solution to free them up without pulling down the engine. It has less than 10k on a rebuild.
I would pour a pint of Marvel Mystery Oil into the crankcase and drive it around town every day for a week. That should free up a sticky lifter. Bob
I can see a sticky valve but not a lifter....Take the Valve covers off and watch the rockers,,,easy to tell that way
I can hear the clicking, but not real loud. Added the mystery oil, been running about 5 minutes. Looks like number 1 is doing well. Virtually no smoke and no noise on that side. Number 8 isn't right yet, but it's better.
Whether or not you have a sticky lifter of sticky valve has not yet been determined. To answer your request on how best to free a sticky lifter: Remove valve cover,while motor is running, tap or rap sharply (do not pound) the suspect lifter using a soft faced (plastic or brass) hammer on the pushrod end of the rocker arm. In many cases, this is all that is required. If that doesn't fix it, get a spray can of carb cleaner and use the little plastic tube to squirt cleaner down the pushrod to soak the lifter (motor not running for this part). Repeat the tapping process. This may take several applications (both squirting and tapping) to either fix the problem or satisfy you that this will not be enough to solve your problem. This is quick and easy and usually works.
Always do the cheap and easy stuff first. Also take it easy while driving it around. A little Marvel down the carb is a good idea, just run the idle up and pour a trickle into it, best done outside of course. Bob
Pulled a valve cover. bad news. broken pushrod - was able to fish 1/2 of it out with a magnet, bent and snapped off. Have to pull the booster/mc to pull the other side, but got it loose and felt under there, seems to be the same problem - pushrod is down level with the head and loose in the hole. Need some help with cause and effect here. What happened? How far do I need to go to fix this?
Broken pushrod won't give those compression test results. Somthing is staying put when it should be moving. The pushrod is the weakest link, so it will break first. That's probably why it got quieter. The pushrod may have fallen out of the rocker while the valve hung open and got jammed up . Chances are you have a valve stuck open and the lifters ate the pushrod. Take it down far enough to get the chunks and find the problem, again look at the valves.
Not so simple after all... I've seen engines with broken rocker arms or bent pushrods when started after sitting for a long time. How do the plugs look? You may have to yank the heads after all. Bob
You may have had the rockers adjusted too tight. When you replace the pushrods, run the engine and adjust the rockers by backing them off until they click. Turn them back down until the clicking stops. Then turn them down another 1/2 to 3/4 turn with the engine off. I usually go 3/4 turn. Don't know how many times friends have had them set too tight and the engine ran like crap. Pat.
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