| These are a couple of troubleshooting questions that Jim has tried to solve for folks in the past. Please, if you have questions of your own, feel free to e-mail him. We hope that this way folks can work happily on repairing their "A" problems, and this page will eventually have a nice variety of real-life problem solving tips! Fire away! |
| How do I tell if my engine noise is a noisy valve lifter or something more serious like a loose engine bearing? |
| 1. Your engine has nonadjustible lifters. The correct way to adjust your valves involves measuring the clearance between the lifter and the valve stem when the lifter is on the heel of the cam. A good way to do the measurement is when each cylinder is on top dead center at the end of the compression stroke and ready to fire. You can measure the clearance by inserting a feeler gauge into the gap and reading the gap when the thickness of the gauge produces a slight drag as you pull the gauge from the gap. Once you know the gap or clearance, you then grind some off the stem to increase the gap or if you need to decrease the gap you grind some of the face of the valve or grind some off the seat to obtain the correct gap. This is not an easy job and is usually only done in conjunction with a valve job. The easy way to adjust is with adjustible lifters. The installation of adjustible lifters involves a good deal of disassembly. You will have to remove the radiator, oil pan, cylinder head, valve cover, and the front timing cover. You will have to lift the valves and shim them open so you can remove the camshaft. Before removing the camshaft, you have to lift the lifters and hold them up with spring type clothspins. Then you can pull out the camshaft. Now drop out the old lifters and insert the new from the bottom. Hold the lifters up with the clothspins, lube the cam with assembly lube or some oil mixed with graphite grease, and insert the cam. Now you can let the lifters go, unshim the valves, turn the engine over a few turns to get everything seated again and then do a normal valve adjustment. 2. As for the noise diagnosis, there are several possibilities for the noises: First you have to make sure that the ignition timing is correct. To do this unscrew the pin that sticks out of the timing gear cover and insert the pin end into the hole. Turn the engine over by hand and feel for the hole in the timing gear. You should just be able to feel the tip of the pin sticking part way into an indent in the gear. At that point check to see if the ignition points are just starting to open. If they are you are ok, if not loosen the screw under the distributor rotor and move the distributor cam just enough to start to open the points. When the timing is correct, put the engine at a somewhat fast idle and pull the timing control lever all the way down. The noise of loose bearings, piston slap, loose piston pins will increase as the spark is advanced and will decrease as the spark is retarded. If the noise doesn't change you can have loose timing gears, loose flywheel, or out of adjustment valves. One way to check for piston slap: Remove three spark plugs, leaving number one in place. Crank the engine over until you feel the resistance of number one piston coming up on compression. Crank against compression until the piston is about half way up the cylinder. Now using the fan, rock the crankshaft back and forth and listen for a metallic knocking sound. If you hear a knock, you have piston slap and the only way out is to rebuild the engine. |
| Mark's response: You hit it on the head. As I move the timing advance to retard the noise decreases. As a new person to the Model A area I think this would be a fairly easy rebuild. We tore the engine down somewhat last winter after we bought it. The car had been idle for 15 years. The valves were frozen but some marvel mystery oil quickly did the trick. How would you know if you are ready to blow the A engine. It's not that bad?? Can you pull the crank without removing the block from the auto? |
| Answer No. 2: First, you can't remove the crankshaft without removing the engine. If I were doing the job, the first thing I would do is take off the oil pan (drain the oil first). With the pan off I would try to move the connecting rod big ends side to side. If one is very loose or has more movement than another then you have the culprit. There should be a shim pack between the rod cap and the rod on each side. These shims might look like a solid piece of either brass or steel. They are actually many leaves pressed together. By trial and error you can remove a leaf or two from each side. Tighten up the rod cap and check for movement. You can also check the clearance with plastigage which is available in any good auto parts store. The clearance should be about .001 inch. If none of the rods have excessive clearance, then you should look to the main bearings where the clearance should be the same. It is possible to adjust the main bearings with the engine in the car but it is not easy. One of the center main bearings has a castle nut located in the back of the valve chamber and is difficult but not impossible. If it turns out that your noise is piston slap, you have to have the engine bored and will have to put in new pistons. If the problem is piston slap, you probably can live with it for quite a while. If it is rod noise and very light it will probably be ok for some time. If it gets progressively worse, it will have to be dealt with or you could destroy the crankshaft or break a rod eventually. |
| In order to get more reliable speed from my Model A should I use higher speed gears or should I "soup up" the engine? |
| If your A will not give you at least 60 miles per hour comfortably, you most likely need a good engine balancing job. The stock A engine is quite capable of up to 70 miles per hour with a balancing. If you go to a lower numerical gear ratio (for the higher speed) you will most likely need to produce more power to turn the faster gears. Producing more power puts more strain on the crankshaft, bearings, pistons etc and shortens the life of the engine. A good balancing job adds about $200.00 to the cost of an engine overhaul and as it requires a complete teardown of the engine, it is the most appropriate time to do the job. |