40 Ply P-9 not running "clean"

[Don St Peter]

Thanks to all! I'm off to see what I can find equipped with the knowledge provided. Will keep you posted.
Don

[Carla]

Don, from those symptoms, the place to start is a basic tune-up procedure.

If the engine runs smoothly and seems to develop a reasonable level of pulling power, badly burned valves are unlikely. It would be prudent, tho, to check and adjust the tappet clearance (valve lash) with a feeler-gage, lest some valves may have worn enough to bring the clearance to nil. Access the tappets by removing the right  front wheel and a sheet-metal panel behind it, then removing the two little plates under the exhaust manifold. Follow the procedure given in the works manual to check and set the tappets.

Your engine's problem is most likely carburetion, try substituting a known good carburetor, and see what happens. A blocked or choked air cleaner could be part of the problem, as well. Try running without any air cleaner temporarily, and see what happens. If your fuel mileage goes up to 15-18-ish or so mpg, the reason will be obvious.

A bad vacuumatic advance diaphragm, or a stuck distributor cam, which won't provide the correct relationship of spark timing to engine rpm, will affect fuel mileage, as will any other degradation in the ignition system, such as deteriorated plug wires, high resistances in the primary wiring which run the coil slightly under-voltage, etc. Have the distributor out, and make certain that the dist cam follows the centrifugal weights freely. Fit new points, condenser, rotor, dist. cap, and be sure to replace the two tiny primary wires inside the dist. Apply vacuum to check the vacuum advance unit, and replace it if it doesn't function.

You'll often find that some previous owner replaced the  original plug wires with the modern cheap 'carbon-track' wiring, which won't work wll in the older systems. Fit new real wires, which, these days, means you have to buy a roll of real wire, 'Packard 440' or equivalent, from a supply house, with suitable terminals (I prefer the 'Rajah' make of terminals).

Go through the full tune-up procedure in the works manual, checking all the little details like battery cables, wiring, etc., to know that you have full voltage at the coil. Clean the front pulley and paint a narrow white stripe at the correct position for timing with a strobe-type timing-light.

Many of these older cars suffer from a combination of simple component degradation from age, coupled with improvised or marginal maintenence, combined with the effects of 'brand x' replacement parts and the traditional ham-fisted 'gas station parts changer'. There's nothing for it, really, but to go through a full inspection procedure, repairing/restoring and/or replacing components and sub-systems as necessary.

cheers

Carla

[John Hendricks]

I read some where that lead was not common in gas until after WWII.  Ply always used hardened valve seats any way.  black soot is not uncommon at the tailpipe along with a bit of water---the products of combustion.  Poor mileage may just be timing,etc.

[Don St Peter]

Thanks for the post Dennis!
I am not using a lead additive as I think it was Jim B that said it was unnecessary on these engines. Do you think a lead additive would help? Could you help me to understand how it would help. I am suprised to find the plugs to be clean ( no carbon build-up) after some 300 miles with this situation.
Thank You
Don

[DENNISKS]

Don
Are you using a lead additive? You may be burning a valve or valve seat. Try doing a compression check. Also a dirty air filter could be partly at fault.

[Don St Peter]

I have been driving my car quite a bit and keep noticing a significant amount of black soot ( carbon I suspect ) on the driveway at the tail pipe. The engine is running smooth, no smoking, little oil usage, but its beginning to worry me because the soot persists. The car is making about 11 miles/gal and suspect it should be doing better. Has anyone else been there and have suggestions.
Thanks in Advance
Don