What next?

[rlovette]

I posted last night--an update on trying to get the '41 P-11 started again. I have spark---but it's not hitting (even with fresh gas in the carb). I'm going to re-check, but I think I got TDC set--thanks to the technical tips section on this site (using the light--#1 in firing position, rotating the dizzy, etc) How consistent should the spark be to the plugs while the engine is turning over? My learning curve here is pretty steep on some things. Thanks for all the tips so far.

Edited August 6, 2009 by rlovette

[Plymouthy Adams]

as a refresher, when did it last run, what have you done that could lead to the problem (ie start a tune up etc) Have you at anytime since it last run pulled the distributor..could you now have spark and at the right time but have splash fouled plugs that will not fire under compression..this is not an uncommon problem when messing with timing and points to get them off and in the process of hunting your problem add to it by fouling plugs..verify that TDC is on compression stroke by checking the exhaust valve for seated and rotor is facing the correct tower on the distributor cap..proper timing, fire, air and fuel (clean plugs) and you ought to at least get a hit...

[rlovette]

I did replace the points, plugs, dizzy cap, condenser, plug wires. When it ran last, it was hard to start--would hit and hit and hit--and finally start. Then, it stopped hitting. About the coil, I think it's the original (wish dad was still here to ask). Am I right in that the coil either works or it doesn't? Thanks Tim--am going to re-check everything (will have to wait until the weekend).

[Don Coatney]

  rlovette said:

How consistent should the spark be to the plugs while the engine is turning over? .

I really do not understand your question. The spark plugs should fire once each time the piston reaches the top of the compression stroke (IE both valves closed). Once the plug fires so begins the power stroke. When the piston reaches the bottom of crankshaft travel after the power stroke and begins upward travel the exhaust valve opens an this is the exhaust stroke. When the piston reaches the top of the exhaust stroke the exhaust valve closes and the intake valve opens. The spark plug does not fire at this time. As the poston travels down with the intake valve open a fresh charge of air fuel mixture is sucked into the cylinder thus being the intake stroke. When the piston starts back up after the intake stroke the the intake valve closes and once again the engine is in the compression stroke where the plug will fire once the piston reaches the top.

[rlovette]

Thanks for the clarification--sorry if the question was worded a bit funny--I was trying to ask if it's possible if there's not enough spark being delivered.

Edited August 6, 2009 by rlovette
clarification

[Plymouthy Adams]

in the process of checking your work, do you happen to know what the compression is on the cylinders...with the prior hit and hit and hit slow to start is indicative of low compression...or you have some very serious current drain when the starter is engaged thus limiting the needed current for ignition...let one of these cars get a weak battery and though the engine will turn evenly, it is slower and the coil is straved for current..

you can for test purposes jumper the power to the coil from an external power source independent of the starter circuit and see if ignition will occur immediately..

[Young Ed]

Tim that might explain why some of these will grind and grind and not start but you push them 3 ft and they'll fire right off. Pushing leaves all the juice for the coil.

[Plymouthy Adams]

exactly my point ED..when a starter is worn, in particular the rear bushing, it allows the armature to drag on the field, current is now out of control..and should you have a less than adequate cable size, maybe even a poor cable end with a voltage drop you have now got a situation where the battery would almost have to be paralled with another to ensure available current for quick start..many tests must be made without assuming to ensure your electrical is up to snuff per say..the specification are listed...these are facts..(ohms law) that are tried and true and can be assured to exist..also an indicator is the fact that very little grinding on the starter will drag the battery to its knees and the high indicated current from the generator for excessive amount of time to overcome the use of the starter..list can go on..

very few people have a current shunt and meter capable to measure the high current at home...taking it to a big box auto place will not necessarly net you a competent test either as most do not know how to do the test..especially alternator outputs..I have seen more alternators ruined in the parking lot than you can imagine by trying to get a full 80 amps out of an 80 amp alternator at engine idle...do not test over 60 percent of the rated output with increased engine speed to compensate for the load...case closed...

voltage drop tests is about the only guranteed method to test a battery cable..the factory book has a ton of invaluable test procedures that if followed will find the falut and rule out anything that is good so you can quickly get to the real problem with less amount of time and money from your wallet..