On Sep 5, I wrote:
>> Subject: 2500 S, timing/firing problem
>> 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?
>On 7th Sept. Doug Mitchell replied:
>For an engine to run, three things must be present.
>
>1. Spark
>2. Fuel/air mixture
>3. Compression
>
>If you have a spark, but taking the wires off makes no difference, you are
>missing one or both of the other two. Check to see if you have compression
>in the first three cylinders. Make sure that you have the valve lash set
>properly. Make sure that you don't have a blockage in the manifold of
>the first three cylinders. Make sure that the front carb is working.
>Make sure that you have the wires on in the right order!
>Sorry I can't help you on the other questions, but hope that my suggestions
>get the car running correctly.
Thanks for the prompt reply and advice Doug.
I covered the above, but unfortunately I think it's more complicated than
that. There is the fourth essential; that the first three happen at the
correct time (which I think is the problem in my case).
Hence all my questions about distributers and timing, particularly
regarding Australian models.
Any further suggestions would be greatly appreciated as this is my only
registered car and I live 25kms out of town!
Thanks, Bill Donald
Tasmania Australia
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