Measure resistance of wires from inside of distributor cap to spark plug
connector with Volt Ohm meter. Should be roughly the same on all four.
Connect a vacuum gauge and see what the reading is.
Check cap and rotor for contact-maybe the rotor isn't properly contacting
inside of cap. I had problems with the Pertronix unit pushing the rotor up
too high. I had to sand the bottom of the rotor so it would sit properly on
the shaft. Someone said that their rotor hit the contacts and messed
everything up inside the cap when they installed a Pertronix unit without
fitting the rotor.
Jan
"Almjeld, Paul" <PaAlmjel@dwu.edu> wrote:
Hi all:
My 1725 engine was rebuilt this summer. I finally got it back in Ol' Blue
this past weekend. Here's the mystery: The engine will start, but runs
only with power on cylinders 1 and 2 --------- 3 and 4 have minimal power -
you can pull off the plug wires on 3 & 4 while running and there is very
little change in rpm. I need to run partial choke and keep rpms at 2000 in
order to keep the engine running. I suspect this is due to the significant
drag on 3 & 4. I have changed spark plugs, plug wires, reset the valve gap,
checked and rechecked the timing - all to no avail. I blew out the gas
lines. I removed the manifold to insure there was no blockage in the
manifold or in the cylinder head. I have a nearly full gas tank. I have to
admit, that after 30 years of Alpine ownership and successfully dealing with
a variety of challenges, I am stumped!
compression - 175 or so on all 4 cylinders
valve gaps set cold to 15 thousands on all valves - I've done this before so
that I'm in the ball park to get the engine started - then when properly
warmed up I reset to factory specs.
ignition spark - normal as far as I can tell - it will shoot a gap over an
inch long - Pertronix ignition w/Pertronix coil
Autolite plugs - new condition - plug wires in new condition - new
distributor cap - even tried an old one - no difference
timing - about 7 degrees advanced - starts readily - even on 2 cylinders!
fuel distribution through a Weber 32/36 and electric fuel pump. All lines
cleaned, fuel flow is excellent to the carb.
gas tanks are nearly full of premium gasoline
checked the valves while engine was running - there is up and down motion on
all intake and exhaust valves. Rechecked the valve gaps with pistons at TDC
before compression stroke (did this on each cylinder)
what am I missing????? This is really frustrating as the distributor,
plugs, plug wires, manifold and carb were removed from the spare engine I
pulled out of Ol' Blue. It was working just fine when I shut it down and
they were only off an engine for an overnight. I am stumped!
Dr. Paul Almjeld
Department of Music
Dakota Wesleyan University
Mitchell, SD 57301
palmjeld@dwu.edu
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