Quote:
: I hope you folks can help, as I am drawing a
: blank, never seen anything like this before.
: This is literally one of those "it ran
: fine yesterday but not today" problems.
: No warning, no signs of trouble. I have a
: daily-driver 1970 slant six, nothing out of
: the ordinary, except that I converted it to
: electronic ignition. A little tired but
: still runs strong.
:
: That is until today. Here is the scenario.
: Start cranking the engine. It spins as if
: you had taken the spark plugs out, just a
: constant no-compression spin. Keep cranking
: it, and within a few moments it will chug
: into the usual slant-six crank. This may or
: may not get somewhat labored before it drops
: back into the no-compression spin again.
: Sometimes you can get it started, and when
: you do, it sometimes will run just fine, and
: sometimes will run rough. In any case it
: tends to die if you let it idle, or if it
: does not die at idle, it dies when you put
: in in gear and try to go. The spin, normal
: crank, spin, normal crank cycle will
: continue for however long you hold the key
: down, if the engine does not start.
:
: It does not backfire through the carburetor,
: though it does seem to breathe back out
: through the carb during the no-compression
: spin. The distributor rotates as it should,
: no stopping or hitching. The valves all work
: as they should. I am definitely getting
: fuel, air, and apparently spark since it can
: sometimes be coaxed to start. Very
: occasionally, when you get it to run, it
: will idle very low. I did have the valve
: cover off, but did not think to check if the
: #1 cylinder valves were both closed at TDC.
: I can do that tomorrow, though.
:
: I had thought either a broken timing chain or
: that it had jumped, but if it had done
: either it would not run at all, and I would
: probably be hearing the ugly sound of
: pistons hitting valves. And as I say, it ran
: perfectly fine just yesterday, and can
: sometimes be coaxed to start and run in what
: sounds like a normal fashion. The trouble
: began this morning, but I was able to get it
: started, whereupon it took me all the way to
: work without a problem. This evening, no
: such luck getting home again. (borrowed the
: departmental vehicle, arg!)
:
: Tomorrow I am going to try retarding the timing
: and see if that helps it get started any
: easier, but other than that I am utterly at
: a loss. Any ideas at all? I can provide more
: details if I have missed anything, or if
: they are needed. Many thanks in advance.
here's a quickie check: hook up a timing light and watch the mark for any drastic variation. a slack timing chain will make the mark dance around quite a bit (several degrees.) a little is normal on an old motor.
while i agree with everyone on the timing chain as a possible culprit, it seems odd that power is not down to the "wait for a mile break in traffic before pulling out into the street" level. retarded cam timing will kill a bunch of torque if in fact all you have done is swap ignitions, do yourself a favor an recheck everything you have done. i think of personal experiences where i had the distributor plate misaligned and the ring on the balancer had slipped causing the advance to be so far off that the car would be a bitch to start but run good once running.
-james
ludite13@cs.com
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