I am using a Mallory 2301105 (YH type) single point distributor, H & H G7 cam, and Lion Speed cylinder head (7.0:1 compression), and Stromberg 97 carb on my Model A ford four cylinder flat head engine. Points are set at .020" and Autolite APP64 plugs are at .035". I do not have a "dial back" advance timing light. The engine runs and pulls great with the exception of low rpms (1200 - 1600 rpm) in 3rd gear. The cam seems to come to life after about 1500 rpm, and depending on the ignition timing, there seems to be a flat spot in the acceleration when shifting from 2nd to 3rd gear. When the ignition timing is advanced to provide good road speed manners, the flat spot in 3rd gear acceleration is nearly minimal, but the car is difficult to start. If I retard the overall timing by twisting the distributor, the engins starts better, but the flat spot rears it's ugly head. I wanted to increase the overall advance range in the distributor to allow for a retarded start and still have enough advance for road speeds, and also "weaken" the springs on the centrifigal advance so the advance curve will rise quicker at lower rpm. The distributor seems to have two pink springs. According to Mallory's graphs, these are the weakest springs. I removed one spring from the distributor and left one in place. This seemed to be a step in the right direction, so I stretched each of the springs to "weaken" them, however, I stretched them too much as the the springs do not pull the weights all the way closed. Idle speed is now irregular and hard starting has returned. Obviously, I need to get some new springs from Mallory and keep playing, just not as aggressively. Will using heavier weights in the centrifigal advance also increase the rate of advance, similar to using weaker springs? Any thoughts, corrections of logic, or advice would be appreciated to help with the hard start/flat spot issue. Phred Hollister 847-312-0926 cell
Check in with the fellas on this thread. They may even have a group somewhere else on here that you can join. Look on social groups in the community drop down at the top of the page or PM one of them and ask. http://www.jalopyjournal.com/forum/showthread.php?t=480060 These guys are pretty dyed in the wool banger speed freaks. I'm not a big banger guy but I don't think your flat spot is caused by the dizzy. I don't know what gear you are running but it may be that you don't have the torque to pull it in the upper gears. Or it may just be a tunning problem IE intake and carb. Never the less these guys are the one to ask. Benno
The Jalopy Journal
