Plymouth Owners Club

OK,  I know it's a dumb question, but here goes. I have a pretty good idea how to set the timing on my PA  but I have two problems. Do you set the timing with the distributor in the retarded position or advanced. I should know this, but it's just bugging me. The other problem is one I've been trying to figure out eversince I got the car running, like four years ago. The PA was the first Plymouth with vacumn advance and it's adjustable. I've never seen a distributor advance like it before, and I've never found anyone who can tell me how to adjust it. I did just find a single sentence, in one of the very few books I have on this car, mentioning a maximum advance. It gives this measurment in inches rather than degrees. HMMMMM. I should have went with a Model A Ford! Oh well if these old Plymouths were easy everone would want one. I still wouldn't trade the old beast for any other, and it does keep me out of the bars! Bill James

Quote from: Bill James on January 14, 2009, 05:35:52 PM
OK,? I know it's a dumb question, but here goes. I have a pretty good idea how to set the timing on my PA? but I have two problems. Do you set the timing with the distributor in the retarded position or advanced. I should know this, but it's just bugging me. The other problem is one I've been trying to figure out eversince I got the car running, like four years ago. The PA was the first Plymouth with vacumn advance and it's adjustable. I've never seen a distributor advance like it before, and I've never found anyone who can tell me how to adjust it. I did just find a single sentence, in one of the very few books I have on this car, mentioning a maximum advance. It gives this measurment in inches rather than degrees. HMMMMM. I should have went with a Model A Ford! Oh well if these old Plymouths were easy everone would want one. I still wouldn't trade the old beast for any other, and it does keep me out of the bars! Bill James

Generally you always set the timing with the vaccumn disconnected so it does not interfere or try to do it's thing while you are working on the adjustment. Then hook it up after setting the tiiming, rev it a little and see if the vacuum changes the timing while watching it with your timing light. Timing light should be on #1 spark plug lead.

Inches would be correct but since you don't have the equipment to measure inches don't worry about it. If it is adjustable maybe there is a restrictor screw somewhere.

Good luck,

Jim

"Perfected ignition" with both vacuum and mechanical advance was introduced in 1935. That, along with better heat control with full length water jackets and the water distribution tube, allowed for a higher compression engine than earlier. The higher compression engine was claimed to deliver both higher power and better mileage.

The timing of my 30u starts with getting the #1 piston in the proper position.  There are no timing marks.  Because the point of measurement was welded closed on my head I removed the head and startrd there.  It was much easier than all the guessing I had done previously.  The 30U has no vacuum advance which should really be a vac retard cuz thats what it does.  All of the 30U advance is in the mechanal weights.  When the engine looses vacuum it needs retarding.  So reallly the vacuume holds the timing point unless the vacuum disappears and then it retards the spark.
The 30U is also a four banger.   regards, jim

Just  to warn you this may be a long posting ::) I'll start by thanking Jim and Plymouths for your response. You have helped me more in understanding how this thing works than all my past study and collecting of data. I think what had me the most confused is considering the "vacuum advance" more than what it realy is. The pocket manual describes it as follows, SPARK ADVANCE (automatic) For all road driving the spark is automatically advanced by the engine speed. A mechanical-vacuum control retards the spark at low speeds when the throttle is closed and the engine is idling. When cranking the engine by hand, the spark is in its full retarded position and advances the moment the engine starts to run under it's own power. I think I've finally got it through my thick head! All the thing does is retard the spark just like the manual lever on older cars, then returns to the preset timing where the mechanical weights controls the "advance" as needed. Wow, what will they think of next!! Now all I have to do is find how much to retard for starting. There is a slot in the mounting plate that allows the distrbutor to rotate about 10/12 degrees and the thing is adjustable with a screw clamp that fastens a wire from the vacuum unit to the mounting plate. One book  states "Vacuum unit travel is 1/4" maximum". So where am I? I've timed the distributor with number one piston .046 inches before top dead center by useing a test lamp in the primary circuit, and adjusted the retard at 1/4 inch travel. The battery was low so I've got it on trickle and will crank the beast tomorrow. Wish me luck and thanks again to all who responeded!! Bill James

Quote from: Bill James on January 17, 2009, 09:18:37 PM
Just? to warn you this may be a long posting ::) I'll start by thanking Jim and Plymouths for your response. You have helped me more in understanding how this thing works than all my past study and collecting of data. I think what had me the most confused is considering the "vacuum advance" more than what it realy is. The pocket manual describes it as follows, SPARK ADVANCE (automatic) For all road driving the spark is automatically advanced by the engine speed. A mechanical-vacuum control retards the spark at low speeds when the throttle is closed and the engine is idling. When cranking the engine by hand, the spark is in its full retarded position and advances the moment the engine starts to run under it's own power. I think I've finally got it through my thick head! All the thing does is retard the spark just like the manual lever on older cars, then returns to the preset timing where the mechanical weights controls the "advance" as needed. Wow, what will they think of next!! Now all I have to do is find how much to retard for starting. There is a slot in the mounting plate that allows the distrbutor to rotate about 10/12 degrees and the thing is adjustable with a screw clamp that fastens a wire from the vacuum unit to the mounting plate. One book? states "Vacuum unit travel is 1/4" maximum". So where am I? I've timed the distributor with number one piston .046 inches before top dead center by useing a test lamp in the primary circuit, and adjusted the retard at 1/4 inch travel. The battery was low so I've got it on trickle and will crank the beast tomorrow. Wish me luck and thanks again to all who responeded!! Bill James

Bill, Sounds like you are on the right track. When you start it remember you will need a final timing adjustment while using a timing light and rotating the distributor with the vacuum disconnected. I have had engines that would not run right on the specified timing so I simply set it where it ran the smoothest and locked the distributor down. One was in a dodge truck, one was a "Y" block Ford 312 in a '57 Thunderbird.

Good Luck tomorrow,
Jim

Thanks Jim, I will do a final "twek" when I get it started, but it will have to be by ear only as there is no timing marks on these old plymouths. The 32 PB has a mark on the flywheel with a window and pointer to set the timing, but I don't know if you could read it with a timing light. The PA and older have none. When I get it started I'll post my results. Bill James

I have been looking for answers to these questions for a couple of years.  I finally found a write-up in an old National Service Manual.  I have re-typed all of the information I could read and would be happy to send any of you a copy if you send me your e-mail address.  The article covers setting the timing and the vacuum spark control.  Incidentally, it is a vacuum controlled spark retard.

Hey Plymouths, I believe!! Your post is what got me thinking the right way to kinda understand this thing. I threw my back out pulling the head, and after 6 weeks I'm about ready to go back to work on it. Mr. rdwilliams I would like very much a copy of the write up you have. My e-mail is thanks everone for your help. Bill James