Questions on engine timing - '36 Dodge

[1936 D2]

I have recently replaced my distributor points base plate because of the stationary point's threaded hole being stripped out. (There has been a jamb nut system used on the stationary point for as long as I can remember. It is a real pain to adjust that way)!
I have carefully cleaned the minor storage corrosion from the new base plate and dressed the new point faces lightly. I am using the "new" condenser that came with the base plate also. I have set the point gap, best I can lightly feel, to .020 with a flat feeler gauge. All plugs are gapped to spec. There is a vacuum advance on this distributor along with centrifugal advance weights under the base plate. Part of the reasoning this was all done is two fold - hard starting especially when hot and a slight but regular miss or engine stutter at sustained high speeds (45mph or more) especially when hot.
I have tried to set the timing using a Sun 6 volt Timing Light, attached to the #1 cylinder, to the specified 4 deg after top dead center, but I can only get it to about 2 deg before TDC when it starts to lower the idle speed significantly and stumble. The timing started at about 14 deg BTDC.
I understand from the Service Manual that the timing can be set with a timing light to the indicated "Ignition Timing" from the specifications. The wording in the specification section reads: "Degrees of crankshaft rotation when points open" = 4 deg ATDC. The Service Manual also states that there is no need to disconnect the vacuum advance when using the timing light for this adjustment. If I were to push the timing down to the 4 deg ATDC the engine would stall for sure. As it is, I had to raise the idle speed at the carb a bit to keep it running at 2 deg BTDC. It also seems to have no power on acceleration while stationary. I have not done a test drive.
So, what am I doing wrong or what types of problems can I expect to try and locate considering this information?

[Ron Lawson]

Hi 1936 D2, I have just looked up 5 manuals for DBs from 1928 to 1938 and the all say 4 deg before TDC Hope this helps Ron

[1936 D2]

BEFORE! OK. Those are all different than my Service Manual that talks about AFTER.
I would be pretty close with where it is now then. I will just trim it up a bit closer to 4 deg BTDC and then do a road test. Thanks for all the time looking this up!
If anyone can tell me more how this "Ignition Timing" verses "Degrees of crankshaft rotation..." thing goes, feel free.

[Dodgy6]

This is some info I have. I will not comment on it and profess to have no knowledge of the timing process. A little knowledge can be a dangerous thing....

Ross

[1936 D2]

Ross: The way that chart reads the timing is 4 degrees AFTER Top Dead Center! That agrees with my Service Manual. (But my car would run poorly at that setting). Hmmm... More info to come I hope!
Say "amigo"... If you are reading this, I wonder if you could check your car with a timing light connected to #1 cylinder and tell me what your timing reading is at idle. You mentioned in another post that your car starts easily with a "half crank". I am trying to go for that kind of set-up!

[Dodgy6]

Like I said, I really don't know. Perhaps you have your engine installed upside down?

Seriously though, there must be an explanation if both your service manual and my book that I understood was some sort of bible for service staion mechanics of the day say the same thing.

Maybe one of the blokes on here that can lick a dipstick and tell you which cylinder is down on compression can shed some more light!

[jpage]

Even the "Motor's" manual says 4 lines after TDC. Couldn't be a typo! I would think it hard to adjust the distributor with the vacuum line hooked up,there's not much travel. I'm not sure that every engine responds exactly to specs.!

[JACK M]

Try this trick.
Hook up a vacuum guage and adjust until you get the most vacuum then retard about 2 inches of mercury.
Works for me most times.

[1930]

If you would like me to clarify with tect or pictures let me know, 1936 Dodge passenger car service manual states...........Piston position when points open .002 ATDC, all sorts of other info if you think it might help, cant remember if you said you had this manual or not sure which manual you are working from

[1936 D2]

I am working from the "Master Maintenance Manual" #D3497.

[1930]

I am working from the "Master Maintenance Manual" #D3497.

Cant read the identification key on the cover of this book so that wont help, if the information I posted above is the same as what your book states than I guess I cant help, if its different than let me know

[ply33]

Ross: The way that chart reads the timing is 4 degrees AFTER Top Dead Center! That agrees with my Service Manual. (But my car would run poorly at that setting). Hmmm... More info to come I hope!
Say "amigo"... If you are reading this, I wonder if you could check your car with a timing light connected to #1 cylinder and tell me what your timing reading is at idle. You mentioned in another post that your car starts easily with a "half crank". I am trying to go for that kind of set-up!

Is that for static (engine off) timing? If so, then when you start the vacuum and mechanical advance units will advance the spark a fair amount even at slow idle. If you are setting by a test lamp while the engine is running and trying to get it back to 4 degrees after TDC then I can see where there could be an issue with it running correctly.

[1936 D2]

What Jason posted MAY be information for a static timing - like an engine rebuilder may use. I am trying to work off a timing light (since I have a decent one) on a live -sort of- running engine. That's why I am hoping "amigo" may be able to do the same test and give me a reading from an engine that is known to be apparently working well.
All the information seems to be contradictory (as is seen in this post). The issues of vacuum advance and centrifugal advance all coming into play on a running engine are the crux of the issue. Right now, I am thinking I should be somewhere around 12 to 14 degrees BEFORE TDC on the running engine (pretty much where I started). But then why is it so hard starting at that setting?
I must admit, I am a bit in a quandary at the BEFORE TDC info from Ron's five sources.
I will wait to hear more as this thread progresses.

[Ron Lawson]

IF an Engine was setup to fire after TDC (the piston being on the power stroke of the cycle) by the time combustion was completed the piston would be at the bottom of the stroke The reason for having detornation Before TDC is that as the piston reaches TDC on the power stroke the fuel-air mixture is already ignited and the full force of the explosion then forces the piston down again To have an engine timed to fire After TDC is a bit like closing the gate after the horse has bolted Cheers Ron

[1936 D2]

Ron: You are addressing the idea that the timing is applied to either a static engine or one that has no other advance features. With the distributor on the '36 having two advance features, both a vacuum and a centrifugal advance, there is advance working on the distributor all the time it is spinning or sometimes dependent on engine vacuum. I am trying to find specs that would allow me to set the timing via a timing light on a running engine. So at least centrifugal advance is working to some extent and vacuum advance to a lesser degree.
I understand what you are saying but we have to take in these other advance mechanisms when setting with a timing light. That is why I think they spec the 4 deg AFTER TDC. But like you say also, this MAY be a spec for a static engine, before the advances are applied.
Still trying to find out what the advance timing should be when these mechanisms come into play. Maybe like 12-14 degrees BEFORE TDC? That's what I need I guess.

[ply33]

...Still trying to find out what the advance timing should be when these mechanisms come into play. Maybe like 12-14 degrees BEFORE TDC? That's what I need I guess.

I wouldn't be surprised if it was close to the specs for the '36 Plymouth. For the '36-38 Plymouth the factory service manual has:

Mechanical advance:
0 degrees at 350 RPM
3 degrees at 400 RPM
6 degrees at 950 RPM
9 degrees at 1500 RPM
11 degrees at 1850 RPM

Vacuum Advance:
2 degrees with 6 3/4 in. of vacuum
11 degrees with 17 in. of vacuum

And, by the way, it shows the static (engine off timing) as 4 degrees A.T.D.C. The '36-38 Plymouth distributor is listed as a AutoLite IGS-4003-B-1 so you can see if that is the same as the Dodge.

There are some slight changes for those advance numbers in '42 when Plymouth got the 218 so a earlier Dodge might have slightly different specs especially if it has a 218 instead of a 201 engine.

Final edit: From the above numbers it looks like if you block off the vacuum advance and set the idle to about 500 then your timing light should show pretty close to TDC (a bit more than 3 degrees mechanical advance from your 4 degrees ATDC starting point).

[hchris]

Try this trick.
Hook up a vacuum guage and adjust until you get the most vacuum then retard about 2 inches of mercury.
Works for me most times.

Jack M has the right idea, you are much better off with a vacuum guage to get the best ignition timing. Dont get too excited with the 4 degree issue as this really is not relevant with todays fuels, the burn time characteristics are vastly different from the fuels of 1936.

What you really need to achieve is a steady vac. gauge reading of 18 - 20 inches at idle, this is accomplished by moving the distributor base plate, with the engine running, just as you do with the timing light.

If you dont have a vac guage, timing by ear will get you close to the mark. Set the distributor so that you get an easy start and a smooth idle; take the car out on the road and get into top gear, then steadily accelerate, if the car pulls away readily without any hesitation or pinging then you are in the ballpark, if it pings you are too far advanced and need to back the distributor off a little.

The final outcome should result in best acceleration just before the onset of pinging.

Having reached a satisfactory setting, then have a look with the timing light so that if there is a next time you know where to set things up.

[1936 D2]

Some great specific info from "ply33"s shop manual. The Dodge manual is not as "informational". Thanks.

Excellent explanation "hchris"! Very clear and good reasoning as to why to not worry too much about the indicated timing from the timing light.
I have a nice vacuum gauge so this should be fairly easy. I thought "JACK M" might have been on the right track!

[JACK M]

Works on hot rods too !!

[1930]

Works on hot rods too !!

It prob. grumbles throughout the whole ordeal

[1936 D2]

Works on hot rods too !!

I suspect it would!

[R.White]

No doubt in my mind, Jack has the best suggestion with a vac gauge but my Dad always did like hchris and set the timing by ear. Either way is probably better than trying to go by the book in this case unless that is what you feel most happy with. Sound advice given here in my view.

Ray

[1936 D2]

Yup. All good food for thought.
Guess I can close off this thread for now.
If I remember I will give a final report as to how the timing was finally set and what may have been causing the hard starting issues.
Too bad I have not heard back from "amigo" yet as to what his running timing looks like. Some day maybe.