Interesting timing problems... ideas

[Nick ALFANO <71amx@xxxxxxxxxxxxx>]

Jesse,

Sounds like you are on the right track with the timing
chain jumping.  Initially, pull of the #1 cylinder
side valve cover and remove number one spark plug. 
Turn the engine over until you start the compression
stroke.  Then start to turn it by hand.  You will need
either a piston stop or some other device to tell when
the piston is at the very top of the compression
stroke (you could eye it).  The timing mark should be
on or very near to TDC.  While doing this, keep an eye
on the valves, they should both be closed throughout
most the compression and power stroke.  If one of the
valves is open during this rotation more than just at
the very beginning or end, than your timing chain has
jumped or is installed incorrectly.  If that is fine,
check to make sure you distributor is installed in the
right position and not off by a few teeth.  If all
that is fine, check for sticking valves and cylinder
pressure.  If you have some valves that are sticking,
try some upper valve train cleaner/lubricant.  My
assumption here is you have already checked the easy
stuff like plug wires are in the correct firing order,
plugs are good, vacuum advance is working etc.

If you have timing chain issues, who knows what else
might be behind that.  A worn out timing chain that is
way off might have done other damage when it jumped. 
You are right in the sense that if you have to pull
the front of the engine apart and change the oil pan
gasket, you could pull the engine in the same amount
of time.  Plus, the 360 will be a lot more fun in a
Commando. 

Nick Alfano
Alfano Performance

Message-ID:
<20060211015550.73652.qmail@xxxxxxxxxxxxxxxxxxxxxxx>
Date: Fri, 10 Feb 2006 17:55:50 -0800 (PST)
From: Jesse <j2sax@xxxxxxxxx>
Subject: Interesting timing problems... ideas
To: mail@xxxxxxxxxxxx

So, I resurrected my 73 Commando 304/3spd.  Got it
from CO for little change because the PO claimed when
her husband died it wasn't running and when a friend
who was a "Mechanic" tried to start it, it caught on
fire.  

So when I went to pick it up, the first thing I
noticed was 3 empty cans of ether in the front
floorboard.  I decided to give it a shot and found no
fuel to the carb.  I hung a gas can from a bungee on
the open hood latch and started some fuel siphoning...
voila!  It fired right up!  Ran like crud though.  

So I towed it home, rebuilt the carb and it started
again though roughly.  Changed the points, coil and it
ran better, but backfired like crazy.  So, I restabbed
the dist and tried to set the timing (advance
plugged).  SO I can get it to idle really well, where
it will rev with almost no backfiring.  But at that
point the timing is so advanced it will hardly turn
over when I go to restart it.  If I get it to where it
will start, it will backfire (mostly exhaust) like
crazy.  

 Attempting to set the timing with a light is
WAAAAAAYY off.  When the engine runs decent, the
timing mark is still about 25 degrees clockwise from 5
degrees BTDC.  If I even attempt to get it close, the
engine almost cranks backwards!  

My belief is that some of the valves are a little slow
due to sitting for several years and that the timing
chain has jumped. 

What do you think of my theory?  I am probably going
to swap in one of the good running 360's rather than
delve deeper unless someone has any fabulous ideas.  I
can swap the engines in a about the same time as
changing the timing chain/cover water pump, oil pan
gasket , re-stabbing the dist and all that timing
chain stuff.  

Do well and have a great weekend, 

Jesse