What techniques do we use today to improve the performance of Model T Ford engines and at the same time retain “period correct” appearance? By Fred Houston
1. INCREASE THE COMPRESSION RATIO from the factory 3.98 to 1. The Model T Ford engine was designed with a low compression ratio because the only available fuels were generally poor quality. Today’s fuels allow our engines to perform nicely in the 6 to 1 compression ratio range, not only improving the performance, but has the added bonus of improved gas mileage as well. Techniques to increase compression include milled heads and/or blocks, pop-up pistons, or high compression heads. For example, for the high head folks, the aluminum Z head has an excellent reputation. A high compression head is believed to be superior to the pop up pistons because of the Ricardo flow design characteristics.
2. CAREFULLY TUNED IGNITION SYSTEM. The original ignition system is excellent, but must be completely rebuilt with magnafluxed and recharged magnets, new field coil, correct field gap and crankshaft thrust, coil box rebuilt and coils rebuilt and tuned with a Strobo Spark Tester. Other ignition selections include original accessory distributors, accessory high-tension magnetos and modern accessory distributors. Because of eBay, the original accessory distributors are more readily available, plus these distributors may now be converted to electronics eliminating the need for the original points and condenser.
3. INSTALL A BILL STIPE CAM – Probably the most important thing you can do to improve performance. A Stipe cam returns your Model T Ford to the original factory cam “low RPM, high torque” characteristics with the added bonus of improved lift. (Note that even the 250 cam has improved lift of .015 because of the smaller .010 recommended gap, down from the .025 range necessary for the factory cam.)
4. THE FOUR TUBE “PERIOD CORRECT” OILING SYSTEM. The four tubes or oil lines are the original internal oil line, the common accessory oil line from the magneto plug to a pan bolt at the front of the engine, and the two accessory oil lines may be installed on either side of the oil pan dipper plate. These two internal oil lines will flow up to a 17% grade, while the standard oil line will flow until a 20 % grade is reached, while the outside accessory oil line will continue to flow up to a 44% grade. An additional quart of oil would be advisable when making a really long pull such as Pikes Peak. Oil line Ratios: Standard internal oil line, 19 5/8” length with a 4” rise (20%). Magneto plug oil line 19 5/8” length with an 8 5/8“rise (44%). Pan plate oil lines 16 ¾” length with a 2 7/8” rise (17%).
5. THE CAREFUL ALIGNMENT AND BALANCING OF THE MODEL T FORD ENGINE AND TRANSMISSION will significantly improve the life of the bearings and crankshaft. Over the past 30 years there has been a siege of broken Model T Ford crankshafts. And why not, the Model T crankshaft is small for the work it does and some are approaching 100 years in age. Having said that, it is my belief that much of the problem has to do with the lack of good alignment and balancing techniques used in the rebuilding process. Further, I believe if one starts with a magnafluxed crankshaft and properly aligns and balances the Model T engine, that the crankshaft and bearings will be long lived. Also there is considerable interest recently on the MTFCA Forum in a new lighter weight bolt-on counter weight based on the bolt-on counter weights available in the Model T era. A good set of counter weights would also help eliminate the possibility of a broken crankshaft.
Some thoughts and comments.
Carb - The guys at the Montana 500 primarily use NH, I believe. Probably for the simplicity. Other factory carbs seem to run just as well, some even better in my opinion. A non-Model T carb is not necessary for speed.
Pistons - Cast iron pistons will not prevent good speed. In fact some of the Montana 500 winners have used cast iron pistons. Should you use aluminum pistons?....absolutely. The Stipe 250 Cam is likely the best low end torque of any cam available today. It is exactly what Frank needs in his 1913 Touring with the 3-1 rear axle. 3-1 equals overdrive and the need for....Yep low end torque. Nothing magic about the Stipe 250. The duration is an exact copy of the 1912 and later Ford factory cam. The ramps are softer and the valve gap is only .010 compared to Factory of about .025, thus combining .015 more lift with the low rpm torque. The top end will get you about 50 to 60 mph.
Always, increase the compression ratio. At the very least mill .125 off the head. The only reason the Model T has such low compression ratio is because of the poor quality fuel available in the T days. A bonus is better gas mileage. You'll get better compression and performance with a Z head because the Ricardo combustion chamber provides better flow characteristics.
