compression test

["Kevin Pacheco" <kevin50187@xxxxxxxxxxx>]

> > When i get to the plugs, what would be a good reading at a 7,000+
> > altitude?
> > Kevin Pacheco
> > 71 Imperial
> >
> >
>
>I need to get my "standard atmosphere" tables out, but my guess is that at
>7,000 feet, you have lost at least 10% of the atmospheric pressure and thus
>density.  So, the compression test would be roughly 10% lower.  If
>the "recommended" number is about 150 psi, subtract 15.  However, the 
>absolute
>number is not that important as much its consistency from cylinder to
>cylinder.  Low cranking speed due to weak battery or starter could for 
>example
>cause low readings.  Also, if you do the test with all other 7 plugs 
>missing,
>you will get higher cranking speed, and higher pressure.  So, it does not
>matter too much how its done, as long as you are consistent for all 
>cylinders.
>If you detect one or two or more cylinders that are far worst that others, 
>try
>pouring a bit of motor oil in the cylinder through the plug hole.  If the
>compression increases, that's bad news.  The problem is rings and the oil
>temporarily sealed the piston.  A complete rebuilt bay be eminent.  If not, 
>the
>problem is in the valves which is easier to repair.
>
>The lack of power you were complaining about could be related to the high
>altitude.  The reduced density will cause a significant loss of torque, 
>along
>with improvement in fuel economy, assuming the carb is not operating rich!
>
>D^2

Thanks again for the help, I hope all is good, and were hoping the power 
problem is due to the timming, Although you said the altitude may cause the 
power loss, my grandfather, previous owner said when he drove it arround it 
was very capible of spinning the tires a bit...
Kevin
71 IMP

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