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Hot Rodding a stock flathead

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Old 06-14-2004, 11:51 AM
philipk philipk is offline
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Hot Rodding a stock flathead

Hey There! I hope someone can help me with a question! I have a 49 Ford F-1. The motor is a stock 239 with dual exhaust. My question is: I want to put a dual intake and a performance set of heads on. Do I need to modify anything or can I just bolt the parts on? Also where would be the best place to get these parts? P.S. What kind of carb should I get to put on the dual intake? Now I have the one stock Holley carb, can I just get another stock carb? Any info would be great!! Thanks Philip
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Old 06-14-2004, 10:32 PM
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Hotting up a flathead V-8

Okay...I'm far from the expert but I can tell you what I'm in process with on my 51 8BA motor. Sorry in advance for the long post.

From what I've read here (and don't overlook the flathead forum as a great resource), in books and other places...the most improvement you can make for a stock flathead is to start with a good set of headers and duals with low restriction mufflers. The Fenton cast iron manifolds (headers) are good performance pieces and still available (but a wee bit pricey). There is a gent at Red's Headers (I think it's www.redsheaders.com but just do a search on Red's Headers and it'll pop up) that is reputed to make some of the best headers around for these motors and they're not too expensive. The Patriot line of headers makes what looks like a copy of the old Belond style center dump headers (which is what I'm probably gonna put on my truck) look good to me. Mufflers are a matter of taste - I'm going with the 26 inch Smithys as I like the sound and the slight extra length keeps them from being too barky. If you want to lean on the loud side go with the 22 inch Smithys or some other glass pack or whatever. For my buck flatheads don't sound very good through Flowmasters but it's a personal thing. From what I read the ideal dually size tubing for a flatmotor (unless it's full race) is 1 3/4 inch tubing.

Next up is carburetion. Most run a set of the old Ford / Holley 3 bolt carbs or the more difficult to find Stromberg 97s. To me the Ford / Holley is a more advanced design and probably better for the street. I might give the Strombergs the nod for all out racing but I think the F/H has a better idle circuit and for a street vehicle that's a better way to go. Of course some people also bolt an adapter to the old manifolds and run even more modern Rochester 2CGs. While 3 dueces look way cool to run them successfully on the street you must also run a progressive linkage to make them work right and from what I understand for the street two carbs is a better or at least a more straightforward way to go and the linkage is easier. You can just get another F/H 8BA carb and that should work fine with the one you have. If you watch eBay you can find them (F/H) fairly reasonably although the prices for flathead stuff has been steadily rising. Stromberg prices are out of sight. Ditto manifolds for these motors...they show up on eBay all the time in both 3X2 and 2X2 variations. You can also buy Offy and Eldebrock manifolds new -see the on line catalog for Speedway Motors - they have a lot of good flathead parts or watch eBay but be choosy as the manifolds get bid up pretty high sometimes. I wouldn't pay more than about $150 for one and at that it's got to be in really good condition. Swap meets are another source for period parts. A new manifold goes for a little over 2bills. The manifold for the earlier motor will fit but the later manifolds give you the ports for the breather tube and oil fill up front - again a matter of taste as much as anything. Be mindful of whether you're gonna run an alternator or stay with the traditional generator as the generator won't fit in front of all the multi-carb manifolds. Some don't even have a provision for the traditional center mount generator/alternator.

The next thing up is ignition and when you go with multi-carb setups you're gonna have to address the distributor advance question as the stock dizzy isn't designed for multi-carb setups as I understand it. Most just go with an aftermarket Mallory or MSD dizzy with full mechanical advance and sidestep the vacuum advance issue. I like vacuum advance for a street motor as it does a much better job of setting the timing for how hard the motor is working - not just how fast it's turning. MSD now sells a "ready to run" dizzy for the flathead that has a vacuum advance built in. They are reputedly a good way to go but pricey.

Because I'm an odd duck and like fiddling with things and know a machinist who also enjoys such foolishness I'm going a home brew route for my ignition. Course it's not done yet so I may be all wet but this is what I'm doing. I have an old style (small cap) points distributor from a C___y being cut down to fit into my 8BA block. I also have a magnetic pickup & reluctor out of a MOPAR dizzy being adapted to fit in the C___y dizzy and I'll use it to trigger an HEI module. I decided to use the C___y dizzy as it's so easy to tailor mechanical and vacuum advance on and the parts are real easy to come by. It will also fit nicely without clearance issues. The MOPAR mag pickup because it's cheap and readily available and actually easier to adapt to the C___y dizzy than a later model C___y mag pickup. An HEI module because they are cheap and bullet proof (and they don't care if it's a MOPAR pickup). The reasons for not just adapting an HEI dizzy in the first place are:
1. It's ugly and looks out of place on a period hot rod motor.
2. There are clearance problems between the water necks on the later heads unless you really stick it up in the air and then its REALLY ugly.
3. It's ugly.
The reasons for not going with a MOPAR dizzy and ignition (which many do and they work just fine) are more personal and mainly because I just wanna do it this way. Nobody said you had to be completely sensible to enjoy this old truck hobby and that's a good thing! Of course the reason not to just stick a pertronix in it is the same thing. I want to build it myself.

If I read the right books, by adding headers and duals, better carburetion and a good ignition to the stock motor (given that the internals are sound and the valves are well adjusted and in good shape) it should make somewhere between 140+ to 150 HP. Add a more radical cam, relieve the block appropriately and add a good set of heads and it's not tooooo hard to get close to 200+ HP for the street. To get more HP than that better bring your banker as go fast flat motors are definitely not as cheap to build as your basic small block anything else. You can make twice the HP for half the cost with a small block anything. But you'll never get close to the sound or the cool factor of the flat motor!!!

For heads the order of the day is bring your wallet. Offy and Eldebrock still make new heads at reasonable prices (about $450) and there are other more limited production heads out there that are much more costly. For a street motor you can't go wrong with either the Offy or the Eldebrock aluminum heads and I think it's mostly a matter of personal preference. I'd be leary of buying used aluminum heads simply because I don't know enough about them to tell if they'd been shaved one too many times or not. They can also develop cracks and you may or may not be able to see them without the aid of dye penetrant. having said that they sell on eBay all the time for serious money - maybe collectors who want old early period heads for a proper restoration. I'd buy new.

One other thing to consider when you start to build more HP you also build more heat and that is the problem with flatmotors. Consider adding an electric fan and good shroud to your radiator. A later style (but low pressure) radiator cap that will allow you to incorporate a proper vacuum catch can is also a real good idea.

Okay that's way more than 2 cents worth - hope it's food for thought and helpful in some way. Let us know what way you go!

Leaks
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Old 06-15-2004, 04:44 PM
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SteV8e SteV8e is offline
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OilLeaks:

Thanks for all the info. I am currently trying to run my engine cooler. I want to add a vacuum catch can. As I understand, you change the cap on the radiator to one that seals and the pressure cap is on the new bottle. How many pounds should the cap be on the new bottle (52 8RT engine)? What about a different fan (not electric) with more blades?
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Old 06-15-2004, 05:27 PM
philipk philipk is offline
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Leaks, Thanks so much for the great info!! The info on the generator and the ignition help me out alot! Are you going to the "Back to the 50's" this weekend in St. Paul? Thanks again! Philip
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Old 06-15-2004, 10:54 PM
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SteV8e, I think you want to stay with a pretty low pressure radiator cap (4 - 6 lbs) and use a modern type that incorporates a vacuum valve...as I understand it you use a catch can with water (well coolant) in it and run a line to it from the radiator cap. As the motor gets hot any coolant that would overflow is allowed to run into the catch can and then when the motor cools off the positive pressure decreases and goes negative - the valve in the radiator cap opens and the overflow into the catch can is pulled back into the system. SoCal speed shop has a low pressure radiator cap and there are probably others as well (I'd check Speedway Motors) and you can use virtually anything as a catch can. An old oil can would be period correct and there are some really neat looking SS units for a few more bucks. I used a large Fosters beer can on the MG for years and it worked just fine. The higher the pressure the cap the hotter the motor can run without boiling the coolant - but the old flatmotor radiators were not designed to run much pressure and it's easy to blow the tubes out of them. If you're running an aftermarket radiator or have had you old radiator recored with a modern type element I think you could run a higher pressure cap and be okay. My radiator is rebuilt but stock so I'm afraid to run over 6 lbs. So far as the fan goes I know people who run modern flex fans on their flatheads but to me the electric fans are more efficient and quieter and you can clean up the front of the motor too. The old fan bearing and shaft was prone to problems and had to be lubed periodically and I just find the electric fan to be a cleaner way to go and you can save some HP. Cost is not too bad either - you can get them off of eBay for around $60 to $70 bucks and you can find them in a junk yard with a shroud (which is probably as important as the fan) for about half that depending on the yard and model you want to get. Take a look at a fan that comes off an old full size Dodge van and see if it won't fit your trucks radiator fairly well.

Philipk, I'll not make the Back to the 50s run in St. Paul - it's a bit of a "fer" drive from central Florida...but it sounds like great fun!

I hope to have the home brew ignition running later this summer. I'll post a note to let you know if it was worth the effort or not. Lots of flatmotors running very well out there with a simple Mallory centrifigal advance...I just like the vacuum advance for street motors and fiddling with things. The MSD ready to run is reputed to be very good...I'm just too cheap!

There is a ton of information on the web regarding flatmotors and more people making parts for them all the time. They'll probably be running strong when we're all gone!

Leaks
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