Packard Forum Index » Pre-War (1899-1942)

Problem:'41 120 runs roughly. Timing is off by light: at max counterclockwise rotation of distributor, #1 fires about 7-10 degrees after TDC; clockwise rotation will stop the engine. I tried moving the wires in the distributor cap ahead, and behind by one hole with no benefit.
Background: car ran and timed well for almost 2 K miles after engine rebuild with new timing chain. Then things got progressively worse. I had recent problems with starting, resolved by cleaning all electrical connections. I have reviewed the related portion of the thread" HA's 52 200 Grey Ghost" (Project Blogs) from a year ago.
Questions: 1. any simple solutions or checks to be made or what have I missed? 2. Should I be looking at the oil pump position? 3. While I have a hard time accepting that the timing chain "jumped" is there any way to check this? 4. Does the front clip need to be removed to access the timing chain? 5. Why/ how could a mispositioned anything happen when it ran so well for a while?

I'd be interested to hear what others think and what you finally wind up finding.

There have been several comments that even when removing the bolts holding the fan, working in close proximity to the radiator acts like a cheese grater on your hands.. Not sure there is enough room to pull the vibration damper to get the cover off with the radiator on either. Even if it is possible to remove the chain cover without removing the front clip I think you would be wise to go ahead and remove the clip just to avoid any possible damage to your hands or the radiator.

I don't see how a new chain could jump either unless it was the wrong one or of incredibly poor manufacture. I would have a question for the engine experts though. Is it possible to accidentally leave one of the keys out or have it mispositioned -- either the cam sprocket or the crank sprocket -- and have it go back together so tightly that the sprocket would grip well enough to run for that long a period before loosening enough to slip on the shaft.

To make sure we are singing off the same sheet, when you say the engine fires at 7-10 after TDC you mean that all the numbers are well below the pointer when the strobe flashes. That is quite retarded indeed, and about what I would expect with the dist. turned all the way CCW. The engine should run as hot as blue blazes at that setting with the exhaust manifold glowing in the dark.

CW rotation of the dist. should advance the timing so the spark is coming before TDC, ie the numbers should be above the pointer, and ideally 6 or 7 right at the pointer.

It is highly unlikely you have jumped time, but that can be checked by checking valve timing as outlined in the manual. You would have noticed a very abrupt change in quality of life if you jumped time.

I wonder if your pointer is bolted to the wrong two holes on the timing case. The change in quality of running over time is easily explained by vacuum leaks developing at the manifold, or even valve adjustment, or the points drifting shut. A change of timing will not effect smoothness unless extreme.

I may not have described things well: the timing strobe now flashes when the timing marks are approaching the pointer. When it ran well, the light flashed when the 7 degree mark was at the pointer. Rotating the distributor clockwise causes the timing marks to move towards the correct position, but the engine gets rougher.
The issue of vacuum leaks at the intake manifold is a challenge! I would think that roughness would be present, but there would be no effect on actual timing(?) I'll have to think of a way to test that. I'll check the (new) points just to be sure they are firmly fixed in position. The pointer is in the same position now as in the past when things ran as expected.
HH56 has confirmed my fears about the way to approach the timing chain, so I'll operate on his and Ross' assumption that a jump is unlikely.

Hi vapackard:

So far nobody has given you a diagnostic path to follow as regards your timing question. Soooo;

a) Number one spark plug wire should be at around 8 O'clock for a properly set up engine.

b) Bring the timing marks to TDC and check the rotor position. Shove a wad of paper towel in #1 plug hole. When it pops, that cylinder is coming up to TDC.

c) Pull the distributor. If the slot in the oil pump drive is not horizontal the motor is not timed correctly. If the crankshaft damper is failing this can lead to a false conclusion. To check, the keyway should be a 12 O'clock with #1 at TDC.

Checking the timing chain means pulling the hood, radiator, grill, to access timing cover. Cover the radiator with a piece of cardboard, cut to fit, to avoid damaging the fins.

Hope this helps.

OK and thanks for the outline. I think I have a) and b) covered (but I really like the wad of paper trick! And I will try it just to see how it works for me.)
Pulling the distributor leads to the question of "what if...?"... and what I have read indicates that I must correct any misalignment by removing the oil pump and turning a notch or two (?). I must say that having removed the front clip for the engine rebuild I am less than enthusiastic about doing it again. This car was a joy to drive until last fall when it started missing when going up a hill, and it has been downhill since because of many problems including corroded wire connections.