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2500 S, timing/firing problem

To: triumphs@Autox.Team.Net
Subject: 2500 S, timing/firing problem
From: Bill Donald <wf_donald@stpatricks.tas.edu.au>
Date: Fri, 5 Sep 1997 18:45:45 +1000
Hi,
car: 1977 2500S Australian model. Twin SU HS6 carbs, manual-od, eng no
MM45565HEA.

problem: it's not firing on the front three cylinders.

I recently took the cylinder head off because it was running very badly,
found a solid mass of carbon 2-4mm thick all around the inlet ports of the
front three cylinders.
I cleaned that off, replaced a couple of exhaust valve guides and ground
smooth the tips of the rockers (probably a mistake).

Once back together I found cylinders 1-2-3 were sparking, but not
combusting the mixture!
Taking the sparkplug lead off (engine running) made no difference.
Could it be a timing thing?

I have the Autobook and most of the Haynes workshop manuals, they say this
engine should be timed to 10 degrees BTDC. Also when putting on the Timing
chain, to balance No. 6 rockers and turn the crank to 2 degrees BTDC. I did
that.
 (as these are English books/specs, does anyone know if Australian models
differ?)

Distributer drive gear - is this supposed to be on a 45 degree angle (as in
the first 2000 Fig.) or at a right angle to the engine block (the next Fig.
says 2.5, but it's fuel injected, is the carb. 2500 version like that or
like the 2000?)

Finally, the distributer seems a bit strange. The mechanical and vacuum
advance work in opposite directions - one advances, one retards. Has that
got something to do with emission control?
Distributer No. is 41654 A 45D6 -> 0577

I have another distributer from a 1974 car in which vacuum and mechanical
work in the same direction. (41536 A 45D6 -> 2074)

Does the HEA suffix in the Engine No. mean high compression? If so, what
ratio? Would that be a carb. or PI engine? If it's PI maybe it's got the
wrong cam for carbs?

Is there anybody with an Australian spec. post-1975 2500 (TC or S) car, who
can tell me how there engine is set up?





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