Identical low compression on 1 & 3 only - coincidence?, Peeling back the 914 revival onion Options

[jrmdir]

Hi everyone:

Well, trying to save this 1.7 is just as much of an adventure as I thought (feared?) Last weekend I was stoked that I finally got it started after 3 years of PO neglect and was able to actually drive it. Now of course I'm learning all about the many things that keep it from running well. Seems as if I have a common set of FI revival issues including high idle, very rich mixture and stumbling.

So after a crash course on the many informative threads on this forum, it seems I need to rebuild the MPS - and no-doubt the TPS is also messed up. Not to mention a lot of sketchy looking vacuum hoses.

But while getting deeper into diagnostic mode I decided to check the compression. Since it runs and idles smoothly (except for the stumbles), pulls pretty strongly and isn't blowing smoke I expected no big surprises, but was wrong! I'm getting a reasonable 124 on both 2 and 4, but only 80 on 1 and 3. I know I need to adjust the valves and recheck when warm, but these readings seem so symmetrical and so far apart I don't think those things will make a big difference.

Again, I've read a number of threads here on compression but I'm still hoping I'm missing something about the 1-3 and 2-4 situation. Any thoughts on why the rear two cylinders might not be sealing after sitting for so long? I've only driven it for about a half mile so perhaps it will get better after re-breaking in?

Thanks in advance for any ideas.

Ron