Re: Ken's 1937 120 Touring Sedan
Posted by Ken_P On 2020/8/12 21:59:38
Owen - thanks for the advice! I inspected the wrist pins, and everything is tight, no odd wobbles or movement. So, unless something changes, I don't think I'll pull the pistons off the rods. If I do, I'll take the connecting rods to a machine shop and have them checked out.
Wesley - yes, the dollies are from Harbor Freight. I haven't had any problems with them, but I don't use them too often. Hope you can find some new casters.
I measured cylinder taper, and think I'm in good shape. The max taper is 7 thousandths on #2. Minimum was 3.8 on #6, and average was 5.5. The Packard motor manual says you should re-bore the cylinder at 7-10 thousandths, but up to 14 was acceptable if the customer wanted to save money.
What I don't understand, is that the motor manual says to use piston expanders if the skirt is more than 6 thousandths under in diameter from the point of maximum cylinder wear. My max delta is 9.1 thousandths between the piston skirt and point of max wear, and the average is 7. But, the average difference between piston skirt diameter and the bottom of each bore is only 1.8 thousandths. Wouldn't piston expanders, or knurling, to correct the first condition make the pistons too tight in the bore by making them bigger than the cylinder at the bottom of each bore?
No smoking gun yet on why the engine didn't run smoothly. Lots of carbon, and the timing chain was slack (1/2-5/8" between the gears). I hoping that that, new rings, and a valve grind, will give me good service.
I am concerned about all the oily carbon buildup on the valves and cylinders. Could that just be caused by rich running? I've only put a few hundred miles on the car in the time I've owned it, and if the odometer is right, it has only been driven 5,000 miles 1953. While I've owned it, it doesn't seem to use any oil. Should I be looking for a problem somewhere else?
Interestingly, all the pistons I've cleaned off are also stamped 55, in addition to having the cylinder number and the letter code indicating their size variance. Not sure if that means anything.
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Wesley - yes, the dollies are from Harbor Freight. I haven't had any problems with them, but I don't use them too often. Hope you can find some new casters.
I measured cylinder taper, and think I'm in good shape. The max taper is 7 thousandths on #2. Minimum was 3.8 on #6, and average was 5.5. The Packard motor manual says you should re-bore the cylinder at 7-10 thousandths, but up to 14 was acceptable if the customer wanted to save money.
What I don't understand, is that the motor manual says to use piston expanders if the skirt is more than 6 thousandths under in diameter from the point of maximum cylinder wear. My max delta is 9.1 thousandths between the piston skirt and point of max wear, and the average is 7. But, the average difference between piston skirt diameter and the bottom of each bore is only 1.8 thousandths. Wouldn't piston expanders, or knurling, to correct the first condition make the pistons too tight in the bore by making them bigger than the cylinder at the bottom of each bore?
No smoking gun yet on why the engine didn't run smoothly. Lots of carbon, and the timing chain was slack (1/2-5/8" between the gears). I hoping that that, new rings, and a valve grind, will give me good service.
I am concerned about all the oily carbon buildup on the valves and cylinders. Could that just be caused by rich running? I've only put a few hundred miles on the car in the time I've owned it, and if the odometer is right, it has only been driven 5,000 miles 1953. While I've owned it, it doesn't seem to use any oil. Should I be looking for a problem somewhere else?
Interestingly, all the pistons I've cleaned off are also stamped 55, in addition to having the cylinder number and the letter code indicating their size variance. Not sure if that means anything.
Attach file:
(98.04 KB)
(92.21 KB)
(118.84 KB)
(77.94 KB)
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