47 ply wont start

[dale]

I have a friend with a 47 plymouth.  If the temp is under 50 degrees it wont fire or start but if he pushes it into the sun and lets the sun shine on the motor for awhile it starts right up.  We think it has bad valves but has real good compression on all cylinders.  The motor has good oil pressure and isnt an oil burner. I had a ford Falcon with a six cyl. once that acted the same way.  Any ideas ?

 

[knuckleharley]

3 minutes ago, dale said:

I have a friend with a 47 plymouth.  If the temp is under 50 degrees it wont fire or start but if he pushes it into the sun and lets the sun shine on the motor for awhile it starts right up.  We think it has bad valves but has real good compression on all cylinders.  The motor has good oil pressure and isnt an oil burner. I had a ford Falcon with a six cyl. once that acted the same way.  Any ideas ?

If you has good compression it doesn't have bad valves.  I suspect this problem is more related to fuel delivery than anything else. Check to see if the choke is working.

 

[dale]

Choke works and. the carb was changed.. the motor runs great once it starts.  Could it possibly be a timing issue >  Has a Pertronics ignition.  Cant see how the ignition could be a problem.

[1949 Wraith]

I agree with Knuckle.  When the temperature is cold,  test it out by pouring a little fuel into the carb before starting and see if it fires

 

[Plymouthy Adams]

when cold, it takes more uumph from the battery to turn the engine, this high current drain is preventing a proper amount of current to generate a decent high voltage spark when the coil field collapses.  I would test the current load on the starter and if it is in excess (check your book for this value) find out if bad bushing in the rear is causing a drag or you may have a voltage drop in your cabling.  Point number two, your battery may not have enough reserve to overcome normal current load especially if a group one battery with a bit of age...charge the battery and have a current test done to checks its ability to provide the current you need.  (again, rating is in the repair manual)

[dale]

It has an electric fuel pump and goes great at all speeds.  I agree with Knuckle also but how do you get great compression with bad valves ?

[dale]

1 minute ago, Plymouthy Adams said:

when cold, it takes more uumph from the battery to turn the engine, this high current drain is preventing a proper amount of current to generate a decent high voltage spark when the coil field collapses.  I would test the current load on the starter and if it is in excess (check your book for this value) find out if bad bushing in the rear is causing a drag or you may have a voltage drop in your cabling.  Point number two, your battery may not have enough reserve to overcome normal current load especially if a group one battery with a bit of age...charge the battery and have a current test done to checks its ability to provide the current you need.  (again, rating is in the repair manual)

Ya that is a good point..We will do that..

[Los_Control]

Also check for spark when it is cold, is it bright blue, or dull orange? Is possible something in the petronics is getting weak, needs a little juice to excite it.

I have seen outside temperatures affect weak failing electronic parts. Had a electric fuel pump that would not pump in the heat of the day, but would pump all night in the cool darkness.

 

 

[Los_Control]

5 minutes ago, dale said:

I agree with Knuckle also but how do you get great compression with bad valves

simple, ya dont. So the only other option is the valves are good if you have adequate compression.

[dale]

5 minutes ago, Los_Control said:

Also check for spark when it is cold, is it bright blue, or dull orange? Is possible something in the petronics is getting weak, needs a little juice to excite it.

I have seen outside temperatures affect weak failing electronic parts. Had a electric fuel pump that would not pump in the heat of the day, but would pump all night in the cool darkness.

 

 

 

[dale]

3 minutes ago, dale said:

17 minutes ago, Plymouthy Adams said:

when cold, it takes more uumph from the battery to turn the engine, this high current drain is preventing a proper amount of current to generate a decent high voltage spark when the coil field collapses.  I would test the current load on the starter and if it is in excess (check your book for this value) find out if bad bushing in the rear is causing a drag or you may have a voltage drop in your cabling.  Point number two, your battery may not have enough reserve to overcome normal current load especially if a group one battery with a bit of age...charge the battery and have a current test done to checks its ability to provide the current you need.  (again, rating is in the repair manual)

The motor turns over easily in the cold.  Ive checked the spark while turning the motor over and it looked strong.  Got a real jolt while doing it. Good spark.. Good compression..runs strong once it starts..  Spark plugs maybe ?  Not good with the electronics part.

 

[Reg Evans]

I had a 47 pickup that would not start on cold or damp mornings unless I removed the dist. cap from the dist. and blew it dry with a hair dryer.  Don't know why but there was always some condensation on the inside of the dist. cap that interfered with it starting until I dried it out.

[knuckleharley]

6 hours ago, dale said:

Spark plugs maybe ?

Maybe. I quit using Champion spark plugs back in the early 70's over almost new plugs dying. Still won't buy one,or even put one in my lawn mower if you give it to me.

For the MOST part spark plugs either fire or they don't,but I did have a 1 cylinder lawnmower engine drive me nuts once trying to get it to start. I was just about ready to take it to a lawnmower pro to get it fixed because it was getting fresh gas,and I could pull the plug and ground it and it would fire. I  decided to try a new plug first to see what happened. It fired right up. Damn thing would spit fire all day out in the open,but the instant you put it under compression it would die. Once again,a Champion spark plug. I got it for free because the guy that gave it to me couldn't get it to start.

I have no idea how that could be related to the engine starting after sitting out in the sun with the hood up,though. Your problem HAS to be  related to a fuel supply problem.

When it is sitting and cold have you tried taking the breather off the carb and manually moving the carb linkage to see if it is spitting fuel down the intake port? If not,your float needs to be adjusted  by either bending the tin arm,or replacing it if it leaks.

If it pumps fuel without the engine spinning over after sitting all night,the float is ok,and your problem is related to the choke. PLEASE note that this test MUST be  done ONLY after the car sits overnight. You could have a very small leak in the float that would cause it to dump all the bowl gas down the intake overnight,but fill the float so slowly that once started in the morning the car will continue to start fine all day.

 

 

Edited December 9, 2017 by knuckleharley

[dale]

Its getting plenty of gas.  Took out the plugs once and squirted in gas.  To cold out now to mess with it but we will come Spring.  Didnt try shorting out a plug to check for spark.  Replaced carb with a new one.

[Plymouthy Adams]

25 minutes ago, dale said:

Its getting plenty of gas.  Took out the plugs once and squirted in gas.  To cold out now to mess with it but we will come Spring.  Didnt try shorting out a plug to check for spark.  Replaced carb with a new one.

until you systematically troubleshoot your cost to find this by just buying parts willy nilly is going to keep eating the wallet...follow your repair manual and as I always say, if you do not know what is wrong, prove what is right....

[rvannoy1]

I had a 47 P15 a long time ago, and I was told by an old mechanic to drill a "weep" hole in the bottom side of the distributor cap to make sure the inside of the cap  wouldn't allow any moisture to accumulate. Worked great after that.

Another check for moisture inside the cap is to put a trouble light next to the cap over a cool night, if it fires right up next morning, you know it was moisture.

Now I have a 48 P15 coupe with a 56 Chrysler 354 with electronic ignition and it starts almost before you put the key in. (However, it stays in a heated garage now).

Edited December 15, 2017 by rvannoy1