I have a 49 Ford 2dr sedan with a good running stock flathead v8. Its only performance modification is a set of headers and dual exhausts running through a pair of glasspacks. I'm looking a tweaking it a bit but don't want to trash driveability. I am definitely going to convert it to twelve volt with and alternator and also change it to and electronic ignition. Beyond that I'm considering aftermarket performance heads from one of the manufacturers and either an intake manifold change with a pair of dueces or a small four barrel. From what I've been reading the latter carb and manifold change is a bit easier and more reliable than the dual carb arrangement. As far as heads are concerned I don't want to up compression much above 8.0 to 1. I would like to stay with the stock cam too if possible in this scenario. Will they adequately handle the extra fuel with the stock cam or do I need to go to 3/4 race grind?
Might as well open the "can of worms" early in this reply process! It's supposed to be a big no-no to try changing the compression ratio of any flatty that's already operating with a lower ratio. So if true, those good-looking aftermarket aluminum heads are out. The other side of this argument contends that you won't be upping the ratio all that much, you're just using the vehicle part-time, and what's a little bluish smoke out on the boulevard Saturday night anyhow?
I'd think a single 4-barrel might be okay to add, as long as it's a teeny one i.e., less than 500 cfm. That way, you avoid rebuilding old carbs, synchronizing them, and possibly using cheap but colorful aftermarket plastic fuel lines which like to melt and start a fire late at night when you're farthest away from home and a fire extinguisher!
Okay, I've put plenty of stuff in this reply to prompt many angry replies, which is just fine with me as long as we get closer to the truth for you, which is what you need most. So settle back for a bit, because I can feel the first angry barb being fired at me 'long about now!
Thanks for the quality input. I'm a believer in the "Less is More" approach for everyday performance applications. The information your guys have offered is in line with what I have found, too. I read a great article in Street Rod magazine a few years back detailing some excellent research on flathead performance. The articles conclusion based on modern engine analysis methods demonstrated that flathead performance deteriorates with increases in compression above 8.0/1 with a decline in power and torque at higher rpms. My 49 as far as I know is stock so that would translate to 6.9/1 in original condition. I can't say what it is now since I haven't gotten into the engine and don't have its complete history. It does seem to be a very good performer however in its current apparently original state. More acceleration and thrust than I expected from this little old V8. I'm an old guy and don't hot rod it but I'm not afraid to use what it has now and then and so far I haven't been disappointed. I'm looking for just a bit more oomph just for grins but don't want to overstress a good thing. Given its age I doubt that it hasn't had at least one overhaul in its life so it could likely have been bored out at some point which might account for the perceived extra juice. So far no cooling issues, no oil consumption, no smoke and no leaks. I am definitely going for the twelve volt conversion and electronic ignition and will probably go the small four barrel carb and manifold route before anything more ambitious. Thanks again for the input.
You might look at adding Ford EAB heads off of a `52/`53 flathead engine. They're factory stock items and increase the compression ratio slightly. I think Ford advertised a 10 hp gain. The old hot rodders swore by them.
As Gary said a set of EAB head would add about 1 point to the compression ratio. they were the highest compression ratio heads that ford made. they had a volume of around 70 cc that is better than some of the after market heads. You should get the book called Flathead facts by John W. Lawson it will tell you alot about.the different speed parts and he backs it up with dyno tests What works and what doesn't work.
Not sure heads will give you the boost you want. For about a grand you can get a 4bbl manifold with a Holly 390 cfm or Edelbrock 500cfm carb and send your stock distributor and have him convert it for you. I've heard good things about this setup. For more info do a search about it at Fordbarn. However,always call Chris first and ask about this He has a wealth of knowledge! Rob