Larry -
It is, of course, imperative that the relationship between the crank
position and the cam position be correct. It's not really possible to put
the timing chain on "180 degrees out of sync", but it is certainly possible
to get the crank and cam out of sync.
Both the cam and crank sprockets should be marked in some manner. If you
refer to the Blowers or TD shop manual, you will find that the proper
position depends upon having the correct number of links on either side of
the sprockets when the two sprockets are lined up with the marks pointing at
each other. (Better you read the book.) It is possible to remove the front
timing chain cover with the engine in place to check all of this. For
visibility reasons alone, it might be easier to remove the radiator. You can
test the engine for short periods with no coolant since it will take several
minutes for the engine to come up to the temperature where no coolant would
do harm.
Before you go and do all of this, however, I would suggest a few obvious
preliminary checks:
1) Have you gone through a static timing test to ensure spark is occuring
somewhere near TDC on #1 cylinder? If it is not, check the position of the
distributor relative to the piston position. It's easy to put the
distributor in wrong.
2) With the crank at TDC on #1, both valves on #1 should be completely
closed. If it were possible to see the cam lobes, you would see them
pointing at about 4:00 and 8:00 o'clock. As you move the crank back and
forth around #1, one or the other valve should be opening. If you move in
the direction of engine normal rotation from TDC the exhause valve should
open. In the opposite direction from TDC, the intake should open.
If this proves correct, then you probably have an ignition timing issue. If
not, you have a valve timing issue. Even if the sprocket position is not
correct, indicating a valve timing issue, by dropping the pan and removing
the radiator and front timing chain cover, it is possible to set things
right again without (horrors!) removing the engine.
Keep us posted.
Regards,
Lew Palmer
lew.palmer@uci.com
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From: mgs-owner
To: mgs
Subject: Valvle Timing
Date: Tuesday, August 01, 1995 9:30PM
My TD engine has recently been rebuilt, however, it won't start. The facts
are:
There seems to be plenty of spark at the plugs.
The compression is about 135psi in each cyclinder.
There appears to be plenty of fuel as the level is just below the jet bridge
in each carb. The carbs are not plugged.
The exhaust does not seen to be plugged.
There is little or no suction at the inlet manifold even when I disconnect
the carbs from the manifold.
Is it possible that the timing chain was replaced 180 degrees out of synch?
When I received the engine from the rebuilder, I did not remove the timing
chain cover to check as I couldn't believe this could happen.
Any other ideas?
Larry Swift
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