mgs
[Top] [All Lists]

Low Compression, 77 Midget 1500 cc

To: midgets <spridgets@Autox.Team.Net>, mgs <mgs@Autox.Team.Net>
Subject: Low Compression, 77 Midget 1500 cc
From: "William M. Gilroy" <wmgilroy@lucent.com>
Date: Thu, 08 Oct 1998 14:29:05 -0400
My 77 Midget (1500 engine) has an oil leak down low
by the dipstick.  I thought it was the pan gasket.
After I put in my new dizzy I found that I was leaking
even more oil.  I found that the oil is not coming from
the pan gasket but from the dipstick hole.  I checked 
the oil, it is full but not over full.  The valve
cover vent is not plugged.  I still get the leak if I 
run the engine with the valve cover vent disconnected 
from the carb. at the valve cover.  Now I figure that the
problem is excessive crankcase pressure even though the
the crankcase is vent is work.  I then ran a compression
test and these are the number I got:

        Cylinder 1:  135 psi dry / 155 psi with oil
        Cylinder 2:  40 psi dry / 60 psi with oil
        Cylinder 3:  75 psi dry / 90 psi with oil
        Cylinder 4:  135 psi dry / 170 psi with oil

I ran my compression tests with all of the spark plugs in, and
I squirted a couple shots of 20-40W engine oil into the cylinders
for the tests with oil.

Now I am wondering what are my options.  I think they range
from a complete rebuild to doing nothing.  I would like something
in the middle.  First exactly what do these number tell me?
Like cyl 4 is it just a set of bad rings and cyl 1 is a set of
bad valves and maybe rings.  What is the correct answer?
What are good numbers for compression?  What would I see on a
newly re-built motor?  Could I get away with just re-ringing the 
pistons and a valve job.  I am trying to explore my options.  I 
would like to avoid a full engine rebuild at this time. 
I can see where that would lead me to many other things (hotter cam, 
paint the car since the engine is out, weber, headers, etc.) and
I currently don't want to do all of this stuff.  Maybe down the
road but not now if I can avoid it.

Thanks in advance,

Bill
-- 
Bill Gilroy
77 Midget
E-mail:    wmgilroy@lucent.com
Telephone: 732-957-4775
Fax:       732-957-4775

<Prev in Thread] Current Thread [Next in Thread>