Posted by PapaDean on Thursday, March 22, 2001 at 11:18AM :
In Reply to: Engine rebuild posted by BOB on Tuesday, March 20, 2001 at 11:30PM :
As one who has ported heads (and a few flathead blocks) over the years, I can tell you that porting on a flathead street vehicle won't give you much power increase. So long as the ports are at least as big as, or bigger, than the manifold runner, do nothing to them.
What CAN be done for better performance, is to install a larger intake valve. Stuff in as large a valve as you can and do a little pocket porting cleanup while you're at it. And ignore those old "wives' tales" about the intake needing to be a certain percentage larger than the exhaust. A larger intake will help whether or not you go with a performance cam. Many can grinders will put a special grind on your stock core, though you will need to compensate for the resulting smaller base circle of the lobe by extending your valve length somehow. Old flathead Ford V-8's have available an aftermarket adjustable lifter with a bolt going into the middle of it for adjustment. What I did back in 1960 for longer valves in my flathead Cushman scooter was to put a blob of weld onto the end of the valve and dress it down to size. You might want to use a blob of hard facing arc welding rod for this (all farmers have this rod for use on plow shares).
One of the best things you can do for additional performance from your flattie is to upgrade the ignition. I'd use an MSD-6A box triggered by the points (no need for electronic trigger!), and then gap the plugs up there around .060" or more. Run as much spark advance as you can get away with, without getting spark knock or hard starting when hot. If your distributor has both mechanical and vaccuum advance, be sure to run the vaccuum to a ported source on the carb. Play around with that intial spark setting to see what the motor likes. I'd start around 15 degrees at idle were it mine.
Someone said above that extra compression doesn't add power, but adds torque. Oops. You can't add torque WITHOUT adding power. More compression adds more power - period. By the way, adding a bigger cam will cut your effective compression ratio, or cranking compression, so you can run even more spark advance than with a stock cam. And that incressed compression ratio will help compensate for the loss of bottom end power when you "cam up".
Good luck and have fun!
Dean Bauer
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