Compression and Vibration Questions

[klweimer]

Back to your question of carbon on the piston heads, I don't think it looks that bad. I think someone else mentioned taping off all the passages before scraping off the carbon, which is a really good idea. It seems like I used a super aggressive scotch brite type pad to clean these up, as a wire brush can scar the piston tops. Once you get the pistons clean (they don't have to sparkle, really), you will want to make sure the sealing face of the block is also very clean.

Did you happen to check the valve lash before you disassembled everything? I wonder about the sticky bucket. I don't think it would cause that vibration unless it was really stuck. You might check that valve to see what it looks like. The other source of vibration could be the flywheel/clutch/pressure plate assembly. The pressure plate assembly is sometimes balanced with welded weights, maybe you threw one off?
Kirk

[RRoller123]

Excellent suggestions, sorry I didn't see this post earlier. I cleaned the Block mating surface carefully with a razor edge and the shop vac capturing the bits. A little bit of SeaFoam really helped too, it turns the solids to a gunk that sticks to the blade and can be wiped off, keeping it out of the holes.

Pistons cleaned with a brass brush and SeaFoam, which again, worked pretty well.



I did not check the valves before I pulled the old head, but they had been adjusted just last year, maybe 2000 miles ago, and were not overly noisy (or quiet). Stethoscope.

I did find one thing that may explain it. When changing the camshafts, the old stock ones were very tight, stuck actually, in the far end journals and I actually had to hammer them through with a wooden dowel to get them out. This may have been the source of the vibration, I am certainly hoping. The new cams spin fine. The car had a fan over ride switch when I bought it and I am guessing that maybe it over heated a few times and caused some trouble in the top end.... #4 where the far end journals are runs hot anyway, and if the cooling system was allowing overheating, that may explain it.

I had the clutch and lightened flywheel redone awhile back but this vibration has been there even before that, and it made no difference. I hope the new top end takes care of it, but I am beginning to worry/think that it is a lower end problem. I hope I can get through the season and then pull the engine next winter and raise the CR while fixing the vibration....