James,
This is how I would read those results for a 1275 engine.....
The rather big differences between dry and wet figures suggests poor sealing
at the rings. Adding oil temporarily improoves the seal and gives the
better reading. If they were good to start with, then adding oil would have
a more marginal effect. I would suspect that you do not have any broken
rings though, as the wet figure would be less likely to improove over the
dry figure if the rings were broken. I may be wrong with this assumption
though.
Even the best wet figure is on the low side. It should be up around 195 or
better. So this indicates probable leakage at the valve seats as well. #3
and #4 are poor enough to suggest that you may have burnt valves on those
cylinders.
Do a leakdown test if you have the equipment, but I think you will be
removing the head before very much more of 2004 has passed.
Guy
----- Original Message -----
From "James Gruber" <thistle_3619 at yahoo.com>
To: "Spridgets Digest" <spridgets-digest@autox.team.net>
Sent: Saturday, January 03, 2004 3:58 PM
Subject: Compression Test
> OK here's the tale of the compression gauge so to speak. I ran a
compression test on the 1275 I purchased and here are the results. These
numbers were taken with a cold engine, sitting on a dolly, and I'm sure
operating temps do make a difference. Battery was fully charged and carbs
were manually opened.
>
> P.O. reported that engine all of a sudden started using oil after an
extended trip. One quart per 100 miles. Plugs are oil soaked and covered
with heavy ash deposits so oil is obviously getting in there someplace. I
did notice that this 1969 vintage 1275 does have a buggered up(American
version of buggered) vented oil filler cap and does not seal properly.
Emission gear has been removed and air injection ports plugged. Crankcase is
vented from flame arrestor and goes up with one hose to a Y connector that
goes into the carbs. No carbon cannister, no vented return line to the fuel
tank etc.
>
> Engine has been sitting for an extended time and I cranked it over for
perhaps 30 seconds before I started the compression test to try and
circulate some oil.
> Dry Wet
> #1 130 lbs 175 lbs
>
> #2 125 lbs 160 lbs
>
> #3 110 lbs 135 lbs
>
> #4 115 lbs 135 lbs
>
> Battery did seem to be cranking slower for tests of # 3 & # 4 Cylinders so
the numbers could be off slightly. Lets give it the benefit of the doubt.
>
> I'm not sure what the correct compression numbers are but I'll guess they
are on the low scale.
>
> Your guesses on oil consumption from ring leakage, valves due to heavy oil
blowby.
>
> P.O. Says no real visible blue smoke but I don't believe that line.
>
> Is it possible the leaky oil filler cap could somehow be allowing the
engine to pull excess oil from the crankcase and inject it so to speak into
the engine or is it time to admit this one is a candidate for Vizardizing.
Your opinions please.
>
> P.S. Planning on doing a leakdown test with compressed air on #3 & #4 to
figure out
> if rings or valves.
>
> Jim Gruber
> Bugsy '68 Sprite (future Bugeye in disguise)
> Dayton, OH
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