How fast can overtightened valves hurt an engine? & Other power loss issues.

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Mar 8, 2005
Memphis, TN
Last summer, I discovered that a shop that worked on my truck Fall of 2009 overtightened my valves when I did a subsequent valve adjustment. Most of the valves were tightened so much that there was barely any free play (or none at all) and I could not even get the feeler gauge underneath the valve.

I re-adjusted the valves to the proper spec last August.

However, since around that time (Fall of 2009) I have dealt with a significant powerless with my engine.

Compression #'s are lower on the valves that were the tightest, perhaps. Coincidence or not? Could the valves being overtightened for approximately one year/ 7,000 miles have a serious detrimental effect?

1st: 148 (130 first try)
2nd:148 (130 first try)
3rd: 125
4th: 130
5th: 128
6th: 148

Also, since receiving my truck back from the shop in 2009, the AFM and TPS are both showing error codes. I will get which error code it is exactly again and post the info.

Could AFM/TPS problems also be associated with powerloss?
Seems like the low rpm torque/power is completely gone. High RPM's is better but not good... Also, the truck misses randomly it seems and at times will buck severely (seems to be random and black smoke can be seen coming from the exaust) Most often occurs in third gear or on heavy acceleration.

Been extremely busy in school and haven't really had a chance to address this fully until now.

~208k miles on the engine and running an h55f.

This once happened on my 4 cyl. mercruiser. Once I re-adjusted I had no problems. Mike
The valves could of hit the tops of the pistons causing the valves to bend. This would cause loss of power and lower compression.

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