In the 18 years that our 1948 Packard Coupe sat in a barn in New York, the rust certainly took its toll on the old fastback! In light of that, it was no surprise that while reworking the engine compartment, we found the TDCmarkings on the harmonic balancer were gone--rusted away! Using a magnifying glass, we could see five of the fifteen timing marks amid a sea of pitting, but no numbers at all. The factory service manual showed N01 UP DC 50 100 150 with 15 timing marks between DC and 150 Our five marks could have been anywhere from 0 to 15°.
There are several ways to find TDC. One is to use a dial indicator on a magnetic base, positioned on the cylinder head. Remove the spark plug from the timing cylinder and measure through the spark plug hole down to the top of the timing piston. Raise the piston up (full position), set the dial indicator to zero, go left past .050, bring back to .050, then go right past .050, bring back to .050. The reason for passing .050 each way is to account for the play in the engine parts. The piston pin at the top of the stroke reaches a point where the piston doesnt move, while the crankshaft keeps moving a few degrees in either direction. We couldn't use this approach, because on our straight eight, the piston is not directly under the #1 plug (the timing cylinder). We would have had to remove the head and set the dial caliper and magnetic base on the block to measure piston travel. Some flat heads have a pipe plug over the timing piston that can be removed to determine TDC.
There is a whistler tool available that screws into the spark plug hole of the timing piston. As the engine is turned over, it lets compressed air escape through the tool, producing a whistling sound. When the whistling stops, you have TDC. It works on 14 mm and 18 mm plug holes, but our '48 has 10 mm plugs, so decided not to buy one of these and go another route with the tools we had on hand.
We have a 1948 Packard Custom 8 4-door with an original marked harmonic balancer, so we were able to use it for reference, first determining that both balancers were the same. To give us a starting point, in our service manual, we looked up Valve timing for hydraulic tappet engines(for our Custom 356 CID engine). We turned over the engine until #8 exhaust valve fully opened, and continued turning the engine until the valve was nearing its closed position. At this time, the tappet plunger should not turn when finger pressure is applied. We kept turning the engine over until the plunger suddenly broke loose and could be turned with our fingers. At this point, the indicator should register 10° after TDC on the harmonic balancer. (On sixes and smaller eights with mechanical lifters, you time on #1 intake valve instead of #8 exhaust valve.) Checking our balancer, we were within 10-15° of our 5 timing marks. We were in the ball park! We then put a reference dot on our car's balancer at 10° after top dead center, this point given to us by #8 exhaust valve closing.
Using our five existing timing marks, we set our dial caliper to double them, equaling 10°. We measured 10° from our reference dot back to give us TDC. We had found Top Dead Center!
To further check this, we used a dial caliper and measured from a slot on our reference balancer to DC. Zero is directly above and in the center of the D. We found a third balancer from a Custom Eight parts car, and after cleaning it up, we could see 1 UP and a hint of DC and some timing marks, so we decided to use it instead of the rusted original. We measured with the dial caliper and found that the distance from the slot in the balancer to DC was exactly the same on all balancers. Using a fine-point marker, we marked 0° above the D on our new balancer. We didnt want to use timing tape, so we used a machinists square to set up the timing marks on the new balancer and a coping saw to cut 0°, 5°, 10°, 15°, then used a fine chisel to cut 6°, which is the correct timing mark for this engine. Now the numbers were punched in using a hammer and a 1/8punch set. We left the original UP, which, although faint, had been there over 50 years, so we felt that it shouldn't be disturbed, but preserved in its original stamping.
To pull off the rusted balancer, we used a three-jaw puller. We cleaned and painted the new balancer, first media blasting, masking the timing marks, primed and painted it dark green. Using a small artists brush, we dropped white paint into the newly-cut timing marks and numbers, quickly wiping off the white with a clean rag, which left nicely legible timing marks and numbers. Before we put the balancer on, we used 320 sand paper to smooth around the balancer sealing surface where it fits into the front seal, and put a little oil around it to allow it to slip easily into the seal and prevent leaking later on.
We installed the new balancer, sliding the woodruff key into the key way and pushing the balancer into place. The harmonic balancer bolt was torqued to 145 ft. lbs. (book calls for 130-150 ft. lbs.). Now the balancer is accurate, looks good, and the engine is ready for timing.
We hope this takes at least some of the mystery out of the preservation and restoration of the old classics. See you next month. Keep 'em driving!