This a little long, but please take a look if you think you can help...
I'm getting discouraged!
Spent Saturday trying to fix the misfiring prob. without really diagnosing the
cause. (this is all for 1275 74 Midget)
Installed a new condenser...screwed down tight. Installed new floats
and needles/seats. Checked the dwell. Could not adjust the points further
than 67, yet the haynes calls for a dwell of 60 +/- 3 deg?? Whats going on?
Set timing (dynamic) and noticed that 1) the timing had
shifted to about 15 deg. BTDC, I set it back to 9 deg BTDC. Furthermore, the
timing marks jumped +/- 2 degrees...perhaps a worn dizzy? Note: The engine
has new internal timing bits..chain, rocker assembley etc etc.
Retuned the carbs with my new unibalance thingy and colortune. The colortune
was actually a bit diff. to use...probably because my carbs are worn.
Went for a test drive...vroom vroom, put put stutter vroom vroom.
It was happening again....sigh. When it misfires it shoots the gas/air back
out through the carbs...is this normal? I would think that the unburnt
mixture would be pushed out through the exhaust?
I drove her again today...ok for a few miles then it happens again, and the
temp. rises a little. I get to my destination. When I get back in to drive
home 15 mins. later, shes running fine again and the temp. goes back to where it
normally sits.
I'm fairly convinced now that it is an ignition problem (this may be obvious to
many of you!) because of the fuel being spat back out of the carbs unburnt...
possibly this is all due to innacurate/variable timing? Note: at idle she wavers
maybe 1000 +/-75rpm. Misfiring occurs more readily under accelleration...
when I shift up, it eases slightly. However, it also likes to misfire
at a constant cruise in 4th occasionally. Hills seem to make little difference
(not a fuel feed problem).
I don't want to blow big $$$$$ on a new dizzy if thats not the prob. How can
it misfire only occasionally? What should I systematically check...what tests
do I use? The Haynes does not mention a misfiring problem like this.
Thanks for bearing with me...
Yours glumly
Marcus
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