Packard Forum Index » Post-War (1946-54)

Ross,

I just installed the new cam, crank and timing chain. I lined up the "O" marking as the manual says. When I am in this position, NO.1 cylinder is not in the compression stroke. If I turn the crank until the intake valve is seated and I feel air rushing out of the 1st cylinder, I see the cam gear 180 degrees out from the crank. I thought that TDC was cam and crank lining up and distributor pointing to No.1 spark plug?

Pardon me for jumping in. TDC can be 1 piston at the top of its stroke on either compression or exhaust. In one case the chain marks will agree and in the other crank rotation they will be 180 apart. Ditto the distributor position. Just turn the crank another full rotation and check again.

Thanks for the quick reply Owen. If I am 180 off, then would changing the distributor do the trick?

Tim

If the spark at #1 plug is occurring as #1 piston is approaching TDC on the exhaust stroke, yes, pull the distributor, rotate the shaft 180 degrees, and reinstall.

That did not work. The factory manual is not clear. What picture shows may be for the 200 engines. Bill Vasser, an old Packard buddy, told me to remove the tappet cover and see where the #1 intake and exhaust tappets can spin. That will be when both valves are seated. I will then see where the "O" line up. At this point I will see where the cam is positioned and maybe I need to just rotate the crank one turn because I think it is on the exhaust stoke.

Tim

I admit to being bewildered. What do you care which stroke the engine is on? Packard might have chosen a point anywhere in the cycle for the marks for their own manufacturing convenience. Just make the timing marks on the gears line up next to each other and the cam and crank will be in proper relationship. The gears and shafts are all keyed and if you align the marks there is nothing else to think about. I like to hold a straightedge from center to center cam to crank to eliminate any question of parallax. Put a new chain on my own '53 just last Monday. Noticeable improvement in snappiness.

The only remaining variable is that the distributor can be installed 180 degrees out as it has a slot drive. Just do your compression test again after the chain and pointer etc is on to determine the compression stroke. Turn the engine CW to the 7 degree mark and make sure the rotor is pointing to #1 and the points are JUST opening.

Tim;

I believe the crankshaft sprocket and the camshaft sprocket marks will align at #1 TDC (many engines do), but from a technical perspective the system does not demand that relationship. The goal is to correctly phase the crank and cam shafts, and the sprocket marks are used for that task. If the engine happens to be #1 TDC then OK that's good information, but the sprocket marks take precedence.

The shop manual section that details the procedure to check camshaft timing could/should be followed. That would be a second independent check to confirm you have correctly installed the timing chain. When I install a timing chain, or timing belt I will frequently misalign by one tooth and try to figure-out if I could tell the difference, and then put it back where it belongs once I know the difference one tooth makes. I will also roll the engine two revolutions several times to verify the alignment marks 'come back together. Remember one tooth 'off' is a sizable offset that should be obvious. Unlike modern interference engines you can't do any real damage if the cam timing is incorrect during some timing mark experimentation.

I also believe the shop manual procedure is there as a diagnostic check to absolve of indict a loose timing chain without the expense of pulling the timing cover. Other than the cold versus warm requirement the timing check could be conducted as routine maintenance during lash adjustment.

I guess I would need to know if the valve lash was set before or after the oil pump and distributor were installed during the initial assembly of the engine. I could easily be talked into the engine was parked at the static timing position (something like 6 deg BTDC) until the distributor was installed so the ignition timing could be set. Then spin the engine a couple of turns while the valve lash was set.

In closing Ross is absolutely correct, only the sprocket marks matter when setting the phasing between the crank and cam shafts.

dp

Dave and Ross,

Thank you for your help. I have attached an image of the installed new chain and gears. I also verified that #1 spark plug was firing on the compression stroke by spinning the engine watching my compression gauge and the sparking plug. I found that the distributor was 180 degrees out and once I changed it, I still can not fire it up.
This car ran very well before I took the head off to get a water jacket leak fixed but the head was not salvageable. I had another head that had all the same casting numbers and had the shop check it out. When I put it together, it ran rough and I found evidence water was getting into one of the cylinders. That's when I think it jumped time.
I took the head off and had the machine shop look at it again and the found a pin hole. The fixed it. I installed it and the car would not run. That's when I decided to check the timing chain and found it sloppy. I have also done a compression test. The results seem low.
#1 = 70
#2 = 40
#3 = 55
#4 = 55
#5 = 55
#6 = 60
#7 = 60
#8 = 70
I then put oil in all cylinders, spun the engine and took measurements again to get 30 to 40 more psi in each. Sounds like the rings are shot, but the cylinder walls had no ridge. Regardless, shouldn't I still be able to start this engine? I have run out of ideas. Any help from you all would much appreciated. Please feel free to call me at 916-316-8383

Attach file:

---

  (233.31 KB)

No1Packardman

OK you fixed one major problem that most of us would take some amount of time diagnosing. I've got a Model A with 4 : 1 compression ratio, so as far as I'm concerned you are correct, that is, the engine should start with the cylinder pressures you've measured.

The next thing is to double check the plug wires . . . make sure the firing order is correct, and the plugs have the correct gap, and are torqued in the head.

Check for the existence of spark while cranking and the timing is something close to the correct value.

Check for fuel delivery and quality. Did the carburetor fill during cranking & is the gas somewhat fresh.

An engine that hasn't run in a good long while will need a good amount of choke to draw a lot of fuel through the main jet. Once fired the choke may be placed at about ?.

Sometimes both my '48 and '54 play games with me and will need some amount of cranking to get running. I never seem to know how many times to pump the gas to adequately prime.

dp

Thanks Dave,

I will double check the firing order and make sure fuel is being delivered. I did at one point have all the wires connected to the plugs as they were sitting on top of the cylinder head and they were all snapping very well. It is hard to believe the firing order would change since all the wires in their harness have a specific length and location. Here in Oregon we can buy non-ethanol gas that is what I only use. I also will will fill the carb from the top by removing the 2 screw cover plate over the metering rods.
I am considering also having the wife crank the engine to see of there is sufficient vacuum pull at the carb.
I will let you know tomorrow of what I find.

Tim