"A Straight 8 Comes Together" - Part 9
Work on our '36 Packard Rumble Seat Coupe has come a long way since last month. Working on this car can tax your patience, as well as your pocketbook! Years ago, I was fortunate enough to find a motors manual, electric manual and reprints of the parts and owners manuals, but these manuals take the position that you have worked on these cars for years and leave out most of the details. These details can only be learned by doing, and by talking with the few people who still work on these cars.
In last month's article, I discussed what had been rebuilt and that we had the engine stripped to the block, having done a complete valve job and were ready to put things back together. The first thing was to put on the newly powder welded exhaust manifold. This was the second time to install it. The first time, we couldn't get it to seal to the block. The problem was that the exhaust and intake manifolds bolt together, and as the exhaust manifold had to be resurfaced, this created extra space between the exhaust manifold and block. The solution was to put in 1/8" thick metal gaskets with "fire rings". Some holes in the block were stripped out and were replaced with helicoils. These are spring coils which are installed by drilling out the damaged hole to one size larger, tap thread that and screw in a helicoil which steps down to the smaller size that you need. These come in kits with everything you need except drill bits, and are available in coarse or fine thread.
On our first attempt, we used stainless bolts to replace the old manifolds studs that had stripped out. After removing the stainless bolts, they were found to be thread worn so we decided to use #8 zinc coated bolts and studs in the block with #8 nuts on each end of the manifold. This allows us to tighten to the correct 30 lbs. of torque. With the exhaust manifold tight, we put on the intake manifold. It bolts to the exhaust manifold with 3-7/16" bolts. The problem was the bolts wouldn't align up, because of the resurfacing of the exhaust manifold, which made the intake too close to the block to get our gaskets into place. The solution was to "wallow" out the 3 holes in the exhaust manifold using a round file. We ovalled them front to back 1/8" which allowed us to slide the intake back enough to slip in the gaskets. With these in place, we put our 3 bolts in finger tight, then using more #8 bolts, tightened down 30 lbs. of torque, and then tightened down the 3 "hot spot" bolts where the two manifolds fasten together. Here was another problem: One hot spot copper gasket was too thin. The solution-spray copper coat on two copper gaskets, put them together and then tighten down. This may seem like a lot of trouble, trying to save the original exhaust manifold, but new ones are made by special orders only and can take months to get for a cost of about $1350. This was a lot of trouble, but it worked.
We were now ready to put on the head. We went with a copper head gasket from Egge Machine. The head had been checked with a metal straight edge and was found to be in excellent condition. We had removed all the studs, cleaned the surface, replaced the studs and put the head on, then torqued the head nuts down to 64 lbs. All accessories were reinstalled. The valves had already been set cold, so after putting on the carburetor, hooking up all linkage and filling with antifreeze, the car was ready to start. Our car had been retrofitted with a single-point distributor. We changed back to dual points and set each set at .018. The wires, plugs, cap, coil and condenser were new, and it was now time to start the car. I got in, turned the key, pushed the started button and the car roared to life. The engine sounded quiet, no smoke, valves sounded good, but we still had a miss!!!
WHAT? How could this be? Well, let's take a break and think about this... After talking with some buddies and reading the manuals, the problem looked like it might be a vacuum leak. The intake had a drip tube to drain off excess gas, with a vacuum ball and seat which pulls the ball into the seat when the engine is running, and releases from the seat to allow gas to exit when the engine is off. This mechanism had been taken off and repaired and worked fine. So where could the problem be? On the back of the intake, there is a fitting with two steel hoses, one for a power brake booster and the other for a vacuum windshield wipers. After checking all connections, we followed the steel lines under the car to a vacuum valve before the brake booster. We disconnected the hose and plugged it and the miss went away. The problem was a vacuum leak at the brake valve. We are now in the process of replacing it, the rubber vacuum hose, and checking the vacuum lines to the wipers and Bijur lubrication system. Will we be driving this car for the Holidays? Looks promising. We'll let you know next month. See you then.