Re: 75 twinspark questions (long)

[jonathan coates <alfa@xxxxxxxxxxxxxxxxx>]

In message , David Masters <david@domain.elided> writes
>[]  DJM:  That wire on the coils is for the tacho.  Is there a chance that 
>you have connected the feed loom to the wrong coils?  They each use a 
>different pin to get a signal from the ECU.  While my dizzy on the head was 
>broken, I could only get a good idle and steady running.  Acceleration was 
>poor.  All I had was spark that was timed for the back plug.  The timing 
>for the front plug is different, I presume.  The coil wires of each dizzy 
>go to front and rear plugs respectively. Apparently the later twin sparks 
>do it differently?
>
Whoa! This sounds like good stuff. Now how do I check which is which?
Hmmm.
Also, what difference would firing the wrong plug make? Swirl in the
chamber?
So far I havent checked whether the front plugs all fire from the same
dizzy cap, just that each pot gets one from each. Which way round should
it be?
Could be some DPO swapped the leads and they're still wrong.
Later twin sparks have sparks on the exhaust stroke to "afterburn" the
fumes as far as I know. (Why two plugs then?)
>DJM:  How about the AFM, have you checked that it moves freely, and have 
>you back probed it (Pins 4 and 5 from memory) with the ignition on, to 
>ensure linear output.
AFM checks out so far as I can tell. I get linear voltage change from
one end to the other, and the movement is free.
I ran the engine with the AFM lid off and was able to see the slider go
full scale just by blipping the throttle by hand. I thought that I would
have to go to WOT at high revs to get it to move all the way. Any
thoughts here?
Should there be a WOT switch inside the throttle switch Assy. like on
the 164? I can get the click for the closed throttle switch but nothing
forther open. I suppose I'll have to get under the plenum and check this
out.
- -- 
jonathan coates

------------------------------