Restoring your flathead

Part 7—final assembly

Hi everybody! Sorry about missing last month’s deadline, but ill-timed computer problems and dental work really blew holes in our schedules and plans. Hope you enjoyed the rerun.

We should now be ready to install the pistons and rod assemblies. With the block upside down on the rotating stand, setting sideways with the No. 1 cylinder side up, start with the No. 1 piston assembly by using your assembly lube mixture liberally on the cylinder walls and pistons.

Rotate the crankshaft until the No. 1 journal is centered at the bottom of the block. Tighten down the rings very solidly in your ring compressor. Remove the cap from the rod and insert the piston into the cylinder to where the ring compressor is resting on the block.

Make sure the rod is lined up with the crankshaft correctly. Using the wooden or plastic handle of a mallet, tap the top of the piston down until the piston is free from the compressor. With the upper bearing placed on the rod, tap down the piston and guide the rod onto the crankshaft. Make sure you don’t get the upper and lower bearings switched; the upper bearing has oil holes corresponding with holes in the rod.

Make sure the journal and rod bearing are wiped clean and place a short (1/2-inch) strip of plastic-gage on the crankshaft and install the rod cap, tightening it down to 65 ft.-lbs. of torque. Remove the cap and check the plastic-gage the same way you did with the main bearings. If it checks out okay, clean off the plastic-gage completely and rub a little assembly lube on both bearing surfaces.

Tap the piston back down and retorque both bolts, alternating back and forth until you have the required 65 ft.-lbs. of torque. Rotate the crankshaft a few times and recheck the torque. Repeat this process on each of the remaining seven cylinders.

When this is completed, use a clean rag and put a fresh coat of assembly lube on each cylinder wall. This not only the start of your break-in, but close inspection of each cylinder wall will let you know if you inadvertently broke a piston ring that you can no longer see. Let’s hope all is okay and we can continue.

Install the bronze idler gear that drives the distributor and oil pump onto the rear of the block interior, making sure it meshes perfectly with the cam. Turn the engine upside down on the rotating stand and install the oil pump and splash pans. Also install the timing chain tower cover and lower pulley onto the crankshaft.

It’s time now to install the oil pan. Use aviation Permatex on the pan and lightly at the joints in the gasket, leaving the gasket surface between block and gasket dry. With the gasket affixed to the pan, rub a moderate amount of chassis lube onto the top of the gasket.

Set a few pan bolts into some of the bolt holes to keep the gasket aligned, and use a heat gun to heat the lube and Permatex. Then let it cool. I am glad you asked, “Why all this and only Permatex one side?” First of all, you will get a good nonleaking seal, but if for some reason you want to remove the pan at a later time, the gasket will stay on the pan without breaking and you wont have to install a new gasket. Try it, you’ll like it.

Go ahead and install the pan onto the block and tighten it down. You should now be finished with the bottom side. Turn the engine right side up and make sure the block drain petcocks are in place. Install the oil filler tube and dipstick as well as water pump, fuel pump and all the exterior oil lines onto the block.

Now is a good time to take the engine off of the rotating stand and put it onto the saddle stand. This way it will be a lot steadier for the rest of the work.

Remember how I told you to wait on the T-shaped oil lines from the block to the valve gang bodies? Now you will see why. Put in your 7 quarts of break-in oil in the crankcase. With a long screwdriver blade or flattened rod, go down the distributor hole and turn the oil pump shaft clockwise until you get oil coming out of the fitting in the block where the “T” tubes to where the valve lifter gangs fit. You may want to use a hand drill to turn the oil pump, but if you use an electric drill, go slow or you’ll get a bath when the oil spews out of the distributor cavity.

Once the oil has started out of the fitting, attach the “T” lines on loosely and turn the oil pump until oil comes out of the fittings. Rotate the crankshaft 90 degrees and repeat turning the oil pump. Make these 90 degree turns at least eight times, making sure each valve has operated at least once. Now tighten the “T” lines and you are ready to put on the valve covers and breather. Use the same gasket procedure that you used on the oil pan.

Now is the time to put in the distributor shaft, so start by setting the timing mark on the pulley to the “I” on the IGN, with the No. 1 piston coming near the top of the compression stroke. Make sure you are not 180 degrees off by watching the piston come up with both valves closed. (Note: Use this mark due to the difference in modern fuels and altitude. You can fine tune more precisely at a later time.)

Install the distributor onto the distributor shaft as well as the rotor and cap. Position the distributor assembly in the position it should sit on the block, and mark the cap and side of the distributor with a crayon where the No. 1 spark plug will be. This will be three holes clockwise from the notch in the cap. Take the cap off and set the rotor near the crayon mark. Note the position of the slot on the top of the oil pump.

Using your long screwdriver (or rod), turn the oil pump to as close as you can to the same direction as the shaft on the bottom of the distributor shaft. Set the distributor assembly on the block so the mounting holes line up. Rotate the rotor until the shaft slips down into place. If you are lucky, the tip of the rotor will be right in the middle of your crayon mark on the side of the distributor.

If you get it just right the first time, you have just made history. However, it will give you an idea of how much you have to turn the oil pump to make it fit right. This may take several tries to get it exact. As you put the shaft down into the cavity, you will notice that the rotor turns slightly as it slips into the idler gear. Keep moving the slot on the oil pump until it comes into place with the rotor pointing near the center of your crayon mark. If you are one tooth off on the gear, you will have a hard time later getting your ignition timing just right.

Now install the eight manifold studs into the block. It will be a good idea to use Loctite when you set these into the block. Set the manifold gaskets over the studs and set the intake manifold in place over the studs. Then put in the four bolts that fasten the intake manifold onto the block. Make sure the manifold is well-centered and tighten it down to 30 ft.-lbs. of torque.

Time to put on the flywheel and bellhousing—this can be a bit tricky because of the close fit. Put the flywheel on first, leaving it quite loose, with only a few threads holding it in place on the crankshaft. Then install the bellhousing, tightening down both the flywheel and the bellhousing into place with the proper torque. (Flywheel is 70 ft.-lbs. on a manual transmission or 75 ft.-lbs. on a Hydra-Matic. Bellhousing is 50 ft.-lbs.).

You can now install the starter, and by using jumper cables and a remote switch, you can rotate the engine with the starter instead of by hand.

Because the heads are still off the engine, they should turn fairly freely after a few turns. After turning the engine over a few dozen times, then wipe the cylinder walls down with a clean rag and rotate the shaft a few partial turns until you have had all of the pistons to the bottom of their stroke. Make sure you have inspected all cylinder walls for any sign of broken or ill-fitting rings.

Rewipe all the walls with assembly lube. Repeat this process several times, constantly checking for proper valve operation and cylinder wall damage. The engine should turn a little more freely each time you do this. When you are satisfied, it will be time to install the heads.

Following the service manual for the proper torque sequence, torque the head bolts to 50 ft.-lbs. Now go through the same sequence several times, increasing the torque 5 pounds at a time until you have reached the required 75 ft.-lbs. Spin the engine several times.

This is a good time to check the compression, making sure the cylinders are close to even. Also check for any oil leaks and correct them at this time. Put in the spark plugs and spin the engine a few more times. By the way, you should have the oil pressure indicator port plugged or an auxiliary pressure gauge in place.

You are now ready to attach the clutch and/or transmission onto the block and set it into the car. After the engine is in the car and the new motor mounts down tight, you can install all the little goodies such as the exhaust manifold, carburetor, generator, fan assembly, fuel lines, vacuum lines, etc.

I know you are anxious to fire up your new engine, but I will wait until next month to go over the first-time start. Be patient and we will see you all next month (good Lord willing and the creek don’t rise or the computer shoots craps again).

—Walt