I've got a 327 in my 54 chevy and the car has been sitting for a couple years or so (life, family, blah). It likely only has about 10K miles on the rebuild. Before I parked it I would occasionally get a backfire sound on acceleration that I assumed was from the glasspacks or header leak. I had dumped some marvel in it a while back ago, and just recently fired it back up. It fired up pretty painlessly and idled pretty damn well, but soon realized I was getting some popping through the carb. Put in new plugs/wires and noticed the old #2 cylinder plug wire was a bit crusty at the plug connection. Pulled new plug wire off while running and noise stopped. Pulled valve cover and rocker for #2 exhaust valve was super loose... 1/8-1/4" easy. Pushrod can be pushed down to lifter no problem and it feels spongy while all others are nice & firm. I'm assuming this is a collapsed/bad lifter, but I have zero experience with dealing with valve/lifter issues. Before pulling intake, etc I thought I'd get some advice... Any help or next step suggestions are super appreciated to get it back on the road!
Inspect it carefully,,a similar thing happened to me with my 327 and it turned out to be a broken valve spring. HRP
Found the photo. Thanks to my pal Deuce Roadster and a couple of other guys it was repaired under the awning of the motel in the pouring rain. HRP
Did you watch the rocker arm action when it was running? That would tell you something. Also look at the rocker arm itself, end of the push rod, rocker stud and spring for obvious damage. If the up-top mechanicals look good, all that's left is the lifter and cam. Bob
I didn't want to break the news to him... I had something similar happen on a 327 that wasn't sitting long at all and it was the cam. Bob
Look at the springs and rockers but compression check.A backfire is ingition at the wrong time or valve is open when fired.Kinda sounds like a burnt valve to me
Thanks Guys... Big help already! Top end physcially looks good and spring on initial review looked good... but will look again to make sure didn't miss something with the spring. Rocker & pushrod look great (pr not bent), but when pushing pushrod down with my hand I can feel it bottom out on the lifter which feels spongy. Rocker was definitely loose! Header for #2 cylinder wouldn't burn my spit off so seems clear to me that exhaust wasn't exiting head/exhaust valve not opening. I'm assuming if the lifter has 'give' by hand then it's not doing its job and is a bad lifter??? If firing it up with valve cover off (and spraying oil on me) is there a way to determine by pushrod movement while running if simply lifter vs. lobe? Sounds like either way it's time to pull the intake and dig deeper to inspect the actual lifter and view the lobe. I should be able to see with a light the the cam lobe where the lifter sits to assess wipe out, right?
I've seen lifters go in one of two ways, internal or external. Internal failure is just that , something shit the bed inside of it. Those are something like pumping a new lifter - they never pump up. ( sometimes they loose oil supply but that generally takes the entire side with it not just one and lots of racket) External- usually the bottom wears off and leads to a hole in the bottom of it. This almost always whipped the cam lobe too. The lifter is actually shorter resulting in being loose at the rocker arms. The spongy comes from pushing on the internal spring with zero hydraulic resistance. Inspection should be obvious . If I were you I'd start cam shopping too.
I wound a 396 in my 33 to tight one night coming home from the swap meet,stayed in it too long floated the valves and push rod pinged the top of the lifter on the outter edge of the lifter and caused the piston in the lifter to lock up and after that there she went lobe was gone and lifter was a bitch to get out also
Disconnect the coil wire and have someone turn the engine over while you watch. If the pushrod goes up and down just like the rest of them its a lifter. If the pushrod don't go up and down the cam is wiped out. Sent from my DROID device using the TJJ mobile app
To do this properly you need to use a dial indicator and actually measure the amount the lifter moves, and compare it to a couple other lifters of the same "gender" (in your case, exhaust) since the cam may have different intake and exhaust lift. Just eyeballing isn't close enough, because a "wiped" cam lobe may still have some lift left in it.
Just eyeballing isn't close enough, because a "wiped" cam lobe may still have some lift left in it.[/QUOTE] If its popping back through the carb as he states in post #1 and this is caused by a worn lobe you don't need a dial indicator, you will see it.
If its popping back through the carb as he states in post #1 and this is caused by a worn lobe you don't need a dial indicator, you will see it.[/QUOTE] All irrelevant because he has a spongy lifter that can be pushed down by hand
A wiped intake lobe will make a distinct popping back through the carb, never heard an exhaust do it.
Don't guess take a look at it. I had a 327/340 poke a push rod through the rocker once. Replaced the rocker and the push rod a kept on truckin' We parked a 65 Pontiac for over a year. It ran great when parked. When we started it up it would barely run. A can of Rislone and a trip around the beltway and it purred like a kitten again. I'm not one to think I have cancer every time I get a pain. So far I've been right but my odds are getting worse.
You have done a proper diagnosis. a spongy feel is a leaking or bad lifter, not a pulled stud , broken spring or bent pushrod, however you may have wiped the cam lobe running with no lifter tension. easy-Pull the lifter and inspect the cam lobe and the bottom of the lifter. If there is no scoring or wear, use a breakin lube on the new lifter and install. Cross your fingers till the lifter is seated after running at high idle. hard-Pull the cam and replace it, along with new lifters.
I am not a believer in things in cans ( overhaul treatment ) BUT I have had good luck wirh STP oil treatment in GM engines. Sometime you have to drive it 50 miles but it works with GM lifters. I put 2 cans in a 350 and the lifter quit making that ticking sound.
Put some STP in a big block mopar once to quiet it down and ended up spinning a rod bearing - I don't recommend that sticky shit to anyone.
Yeah, it has the viscosity of road tar in January... I have a can of the OG formula STP on the shelf, a good place for it. Bob
Had the same problem a few years back with 283. Turned out a rocker stud pulled out a tad. Do your heads have screw-in or press-in studs?
All great info & suggestions... I'm going to start tearing into it in the morning and take some photos to share along the way. Fingers crossed it's just a lifter!
So I pulled out the bad #2 exhaust lifter today and it was well worn out on the bottom... to the point of having a pinhole in the bottom of it. It was naturally dry/empty as a result. I don't know if most of lifter damage happened after tightening slop out of loose rocker on an already collapsed lifter? I had fired it up to see if valve would open, which it did, but didn't drive it. I pulled the intake lifter out for comparison and it looked great. The lifter bores feel clean & smooth. The cam lobes on #2 intake & exhaust both feel smooth and visibly (looking with bright light down lifter bore with mirror) look okay. I didn't see any odd wear, grooves, etc. on them (cam still in car & didn't turn motor over). I was expecting to see clear signs of wear on the lobe but didnt. I'll attempt attaching photos of the bad lifter for reference. I went to the parts store and picked up a new lifter. Thoughts on next steps? Cam lobe fried at this point? Install the new lifter , reinstall intake, adjust lash, and fire it up?
98.7654321% chance the lobe is fucked too. Is that lifter worn like a dish or a cup? Imagine that on a flat lobe That hole and majority of wear was the cause of your spongy feeling
If the picture you posted is the bottom of the lifter you've wiped the cam. Don't waste your time trying to get it running again as every time you fire it up you've got metal shavings being flushed through out the engine. At the minimum, time for a new cam and lifters but if it were mine I'd pull the engine, tear it down and flush everthing clean. Reassemble with new cam and lifters and start from scratch with proper cam break-in. Tough pill to swallow but anything else is just throwing good money after bad. Frank