Restoring your flathead

Part 4—The final takedown





It is good to see so many of you back with the stamina to continue. The response to this series of articles at our meetings, personal visits to my shop and by phone have been very flattering. So, what do you say, shall we get right to it?


With the timing chain tower now off and both gears and the chain fully exposed, rotate the crankshaft clockwise to make the chain tight on one side and measure the play on the loose side. Reverse the rotation and measure the play on the other side.


If there is more than one-half-inch play on either side, or if there is any significant difference of play in the two sides, don’t even consider reusing either gear or the chain itself; order a new set. Incidentally, these come in a matched set of all three pieces. They are not that expensive and should not be mixed.


After removing the nut from the cam gear and the bolt in the end of the crankshaft, pull the gears forward off of the shafts, doing each one a little bit at a time using a gear puller or small pry bar until all three pieces come off. This is a good time to take out the two Woodruff keys and mark them in a small bag. Before you decide to reuse this assembly, clean and inspect all three, and if there are any flaws or sharp edges, get a new set!


It is now time to pull the camshaft out of the block, but first, mark the plate holding the camshaft in with a small center punch so you know exactly how it goes back together. This plate is slightly eccentric and has four ways to go back up against the block, but only one way is right.


After removing the two bolts and pulling the plate off, clean and polish the plate. Look at it closely and you can see why the punch marks were needed. Carefully pull the camshaft out of the block. Clean the camshaft real good and polish all of the lobes and bearing surfaces.


If you find any flaws (cracks or pits) or signs of uneven wear, have a specialist regrind the camshaft. If needed, they will use a metal spray process to build up the cam prior to regrinding. Your machine shop can advise you on this.


Time now to remove the valves and springs, which is fairly simple with an inexpensive valve spring compressor tool. First, slowly compress the spring, remove the keepers, (a little trick to help you here is to use a small magnet to keep from losing these elusive and slippery little devils), release the compressor and take off the lower valve spring seat, the spring and the upper valve spring seat.


Sometimes the upper seats can be stubborn and I find a bent dental pick can be very helpful. Both upper and lower seat must be taken out, and along with the keepers, need to be cleaned very well. By the way, new keepers are available through most of our hobby parts houses. Repeat this process for each of the 16 valves.


It is a good idea to mark each valve in the event you decide to grind and reuse the old valves. As for me…well, I prefer to use the new stainless steel valves, as they are readily available and will let you use unleaded fuel.


Valve springs should be replaced as any weakness or variation in spring strength will usually cause annoying valve noise when the engine is running.


Ready to start removing the pistons? Before starting this removal, you should use a ridge reamer to remove the ridge at the top of each cylinder wall of the block. If the ridge is not too deep, you can usually use a cylinder hone with an electric drill to smooth the walls enough to facilitate removing the pistons.


Now you rotate the block on the engine stand to where the crankshaft is upward. Rotate the crankshaft so that the No. 1 and No. 2 rods are easy to get to. To remove the rod caps, you will need a heavy-duty thin wall socket (after all, these should have been tightened down with 65 pounds of torque).


Loosen the two bolts until the washers are loose with about three-sixteenth of an inch play, then use a brass or plastic hammer and lightly tap the heads of the bolts until the connecting rod is loose from the crankshaft. Now remove the bolts and lower cap and bearing. Notice that the two bolts are different and not interchangeable.


Also notice that both the rod and the cap will be stamped on the side with the cylinder number. These marks also tell you the right way to put them back together. A word of caution here: the lock washers for the bolts holding the caps to the rods are a special size, very hard to find and are not standard. Try not to lose them.


With the cap off, push the rod and piston down and out of the block using the handle of a rubber mallet and hitting the rubber end with the palm of your hand. You may need to rotate the crankshaft slightly several times to make it easier to take out the piston assemblies. As each piston is removed from the block, reassemble them loosely and put them aside for now. Cleaning up these rods is a good project for you while waiting on the machine shop.


At the back of the inside of the block, you will find a bronze idler gear that turns the distributor and oil pump from the camshaft. It is held in by a bolt and a pinned washer. Remove and clean this gear real good. Inspect this gear closely and if it shows signs of excessive wear and/or sharp edges, it needs to be replaced. They can be hard to find, so start looking now. If this gear is bad, it will be very difficult to put a good tuneup on your restored engine.


You are now ready to pull out the crankshaft. With the block upside down, take off the three main bearing caps and the support brackets for the oil pan baffle. You may want to mark the center and front main bearing caps in order to identify them at a later time. Clean them well.


Okay, now comes the hard part. Lift out that heavy crankshaft, and lo and behold, you have a bare block and three tables full of mostly ready component parts ready to reassemble.


I don’t know about you, but, after lifting that heavy crankshaft, it is time for a rest and next month we will get our block and other parts ready for the machine shop. Whew!!


See ya next month.