My '51 Chevy had been on the lift too long!
Over a year, while we did a complete brake job--everything, (See www.southernwheels.com and visit the Archives section) and with the car up, we cleaned everything, painted, undercoated the bottom side, replaced the dented differential cover and put in new Lucas 85-90 weight gear lube (NOT silicone), and new front stabilizers. What remained was to have the front seat recovered in original fabric (the back seat is near-perfect), finish buffing the nitro (again), put on a new muffler and tune it up.
This issue will be on the tune-up.
ABOUT THE CAR: The 1951 Chevrolets were available with two straight six engines: The 216.5 CID for the manual cars and the 235.5 CID for the automatics. My car has the 216. Both were good engines, but had different engine lubrication systems. The 216 used the Dipper/Splashersystem and the 235 had Fullpressure lubrication. For our purposes, we will only cover the 216 Dipper system. In this system, the camshaft and crankshaft have four bearings each with the oil pump being driven by the camshaft, supplying oil under constant pressure via a spring-loaded bypass valve providing oil to the main bearings and camshaft bearings. The connecting rod bearings are lubricated at all speeds by Dippers,one on the end of each rod bearing cap. As the crank turns, they dip into oil filled troughs in the oil pan scooping up oil out of the trough. This occurs during start-up and at low RPMs. At high RPMs, where the oil would be batted out of the troughs, lubrication is maintained by oil nozzles which squirt oil into the bearings under pressure. Cylinder walls and pistons are lubricated by the oil spray thrown off from the connecting rods. The valve mechanism is lubricated by oil pumped through the hollow rocker arm shafts.
These engines are tough low speed engines. If you drive 60 mph or under, they seem to last forever. My dad bought a new 52 Styleline (Notch-back), drove it daily and made many 600+ mile trips with us playing the AM radio listening to as much early Rockas he could take, and despite the rock n roll, the car still looked and ran good when he sold it eight years later. The 235 would be the better choice if you wanted to drive and sustain speeds over 60 mph.
TUNE-UP: Even though the 51 had been on the lift for a while, it had been started regularly, had a battery maintainer and had the gas changed every 5 months, so when the brakes were finished, it was no surprise that it started quickly with no missing when we took it out for a test drive. The surprise was after I did some cleaning under the hood. It didnt start! I re-traced my steps and discovered a frayed wire on the starter solenoid going to the (+) side of the coil. It was shorting out. I replaced the wire and soldered and heat-shrunk the terminals on each end, then checked and cleaned the other wires on the solenoid and removed and re-sleeved the (+) battery cable. I was going to replace it, but none of the strands were broken and it had GMstamped into the copper lug at the starter. I buy my high heat sleeve by the roll from Kool Mat.* It is available in black with a woven finish and looks great and reduces the heat at the cable.
To begin the tune-up, I removed the distributor cap, seeing the points looked whitishas if they had overheated, a condition usually caused by a bad condenser or coil. Continuing, I removed the wires, spark plugs, coil, rotor, condenser and points and made another new wire for the coil (-) side to the distributor. The 51 Chevys are negative ground 6 volt systems. The wire from the coil to distributor depends on the groundof the system (negative ground, negative side of coil to distributor; positive ground, positive side of coil to distributor).
When ordering parts, I ordered newcap, rotor, coil, points, condenser, and GM plug wires (stranded wire OEM black lacquered wire type). I have a stock of new, non-resistor spark plugs. Here I used the short5/16length throw (threads) Auto Lite 295. They cross over from the AC 44 or 45 (non-resistor) plugs that were originally used. I always take photos before taking anything apart, and I did on this, but I wanted to find Top Dead Center and #1 plug without looking at my pics.
Most manuals show #1 plug at 12 oclock. I found one that had #1 at 6 oclock. Turns out that the illustrations are just to show firing order and sequence. Im not sure why they didnt show the cap turned to the #1 @ 5 oclock position, but once youve found TDC, the rotor will point to 5 oclock. Using a remote starter switch (you old school guys will know what this is: Just a button that activates the starter solenoid, NOT a remote that you point at your computer car from inside the house to start and warm up the car),I turned the engine over until #1 cylinder was UP on its compression stroke. Number One plug is the plug at the front of the engine, then #2-6 in sequence going back toward the firewall.
There are several ways to find Top Dead Center (see SW Archives). I found it using my whistler that screws into the 14mm plug hole and whistles as the piston comes up pushing air out of the cylinder. That set the rotor to point at the 5 oclock position on the car. I then checked this with my photos. It was correct! The firing order is: 1-5-3-6-2-4 (clockwise rotation).
I removed everything from the distributor, but left it in the car. Then I cleaned up the distributor plate. I bought two sets of points; an OEM Delco set #1855720 and a new replacement set, same number. When I compared them, the aftermarket sets armhad the hold for the insulated terminal connection out too far on the arm. I installed the OEM setperfect fit, I cranked the engine around so that the distributor shaft was on the highlobe of the cam. This is where I loosened the screw and set the points. New points are .022; old points are .018 (the new ones will wear down to .018 over time (.018 is the ideal setting), later re-checking is a good idea). Then I put just a bit of distributor shaft lube on the shaftnot on the pointscontacts. This helps to prevent wear as the shaft rotates. I used new lock down screws on the points and condenser. As I put in the condenser (#192811) I saw that the aftermarket condenser hold down bracket was too long and had to be filed down so that it wouldnt hit the distributor housing (always save old parts!), then put on the rotor and cranked the engine around. Everything looked good. now for my NOS, never-out-of-the-Delco Remy-box distributor cap. What could possibly go wrong? It didnt FIT! It was the correct #824735. The cap is hard plastic with an inner ring that fits inside of the distributor housing. The problem was that the inner ring was just a fraction too big, so that it didnt lock into the housing and was very hard to clamp the clips. I set down with a Dremel and burr, and slowly went around and around, cutting some off of the outer diameter of the ring, blew off the dust, put it on, pushed it into the distributor housing, and that nice popwas heard. The clips snapped right on so easily. The spark plug wires were the stranded 7mm type and were pre-cut. They just needed the distributor end boots put on. They went on tight, but I used a little dishwashing liquid on the lacquered wire covering and they pushed on, then put on the wire ends/distibutor cap contacts. I like these wiresthey have GMstamped in the spark plug ends and they are available from Chevs of the 40s.* I also used the big O-rings, one that groups the front three plug wires and one for the rear ones, also from Chevs of the 40s. The new coil is a stock 6-volt and the 6-volts dont use ballast resistors as do the 12-volts, so you dont have to worry about getting an internal or external resistor coil. The Auto Lite #295 14mm plugs are available at speed shops.*
I also use them on my 51 Packard. The gap is .035 with a roundwire gauge. I put just a touch of anti-seize on the plug thread away from the electrode to make it easier when they need to be removed later. The plugs torque to 20-25 ft/lbs. Before I started the car, I removed the cap and cranked the engine over and saw that I had fire at the points, and checked to see if the glass bowl AC fuel filter was full, then put the cap back on, turned the key straight up, pushed the button and the car started immediately.
Its great when things work out. With old cars, patience is key. Now we are going to put on a muffler, clean up the original interior and when the front seat comes back early September, install it and enjoy some North Georgia Fall driving. I will publish some exterior and interior pictures in a future issue. Keep em driving!