I own this geo metro that I've had for10 years. After what I've suspected was burnt exhaust valves , I've been in the process of rebuilding the head. After seating the valves (new exhaust and original intake), springs, retainers and keepers all installed perfectly. tonight I dropped the lifters in their correct lifter bores(overhead cam) and installed the camshaft with newcamshaft seal. When I flipped the head over to check how the valves were seating with cam installed, I noticed that none of the valves were seating fimly( all were gapped). So now I'm wondering about my lifters. I know I did not store them properly in a container of oil. Maybe they should be replaced? Could the oil have leaked out? I did not replace them to begin with because the surfaces looked so good. Is it possible that they were gummed up from the beginning and it's part of my original problem? Does some member out there have experience with this very thing? Thanks

 

Help again

 

RR,

Enlighten those of us who have never had the honor of working on a Geo cylinder head, please. Does the head use rocker shafts? Is it a single cam, or twin? Do the valves use followers (like rocker arms) or straight tappets? Did you trim the valve tips after grinding the vales and seats?

If the tappets were not soaking in oil and are hydraulic lash adjusted, they should actually tend to be shorter, not longer, providing more lash or gap, not less.

 

Thanks Vader, The head is a single cam head. There are no rocker arms or rocker shafts. There is an inline lifter bore galley in which the cam mounts directly over. Within each bore resides the valve,valve guide ,stem seal, valve sring ,spring seat , retainer and keepers. The tappet( about 1 1/4 in diameter) slides into the bore and makes contact with the tip of the valve stem. All I can come up with is that the lifters (while sitting in their bores without camshaft installed) are protruding higher than they should . When I go to install cam, the lobes( non opening positon) will make contact with tappets before the camshaft journal seats. Also I did not have the seats professionally ground, just took some lapping compound and spun the valve against the seat, so an unmeasurable amount of material was removed. Could my lifter plungers have expanded over the disassembly period? being they did leak some of their oil out?

 

Well, for those who've wondered about my progress. Looks like the valve stem ends will have to be grinded. The replacement costs for lifters on this engine are 37.50 a piece! Not that i suspect the lifters though. Well, maybe , If i could get my hands on a new one to see the height of the plunger( no one stocks 'em). The plungers do move , so I will grind the stem ends till they seat nicely with cam installed. Actually, I believe the valve seats have recessed over time and caused my burnt valves,. When I originally disassembled there wasn't a clean seat in sight. So... there it is.