"Traditional" In 1959, I built a manifold for my 259 Studebaker in My 36 Coupe. It was 4 97's. But as Far as I am concerned if you built a 2 X 4 manifold for your flathead, it would be just as "Traditional"!!
Most flatties can't even handle 3 dueces (94s or 97s) at WOT. Each of my Stromberg 48s is rated at 175 CFM for a total of 350 CFM wide open, which is probably already over-carbureted for my 255 (260 with overbore) flattie. Why have dual quads if you can't use them? For looks? To me, it only looks like you put on too much carburetor.
i'm impressed.this is no different than the early guys(thickstun,weiand ,edlebrock,navarro,evans,ect.) tryin new manifolds and carbs for better power.even if it works no better,no worse,it's still a one off awesome manifold.
Mike, I don't know why you think the engine is overcarbed. Many people run 4 97's with direct linkage, not progressive... And that's over 600 cfm. I think the engine has to be built correctly tho My engine will be able to use the carbs well, I think
Jimmy, It's only arithmetic. A gasoline engine is basically an air pump that pumps half its displacement's worth of air each time it rotates. Since a 4 stroke engine takes 2 full rotations to complete a combustion cycle, it only needs a carburetor that flows half as much air per revolution as the engine size, and then you even have to subtract for inefficiencies, because no engine flows at 100%. The bottom line is a given displacement engine can only flow so much air, no matter how many carburetors or how big a carburetor you install. You can do a search for CFM calculators to figure out max CFMs, but I'll tell you right now that 600 cfms on an engine smaller then 300 cubic inches, especially a poorly flowing flathead (no matter how much to modify it) is way high. When you "overcarb" the problem results from the carb(s) not being "used" to their designed capacity.
Jim is a friend of mine and I too scratched my head a bit when he told me about his dual quad flathead. But, I think it is going to run great even if it never meets its CFM potential, so to speak. I think the biggest thing will be the "wow factor" when he opens the hood at shows. I admire Jim's workmanship. He should post a pic of the overdrive set up he has to go behind the flattie but it is O/T here.
I hear you regarding the wow factor (even if I disagree), but "never meeting CFM potential" is a potential problem because venturis and jets are designed to have a certain flow through them to work properly. Low and mid throttle performance particularly comes to mind. There are guys out there that recommend using three Stromberg 85s instead of three 97s on flatties. I take their point. To each his own.
It was just something I wanted to do. "You can do a search for CFM calculators to figure out max CFMs, but I'll tell you right now that 600 cfms on an engine smaller then 300 cubic inches, especially a poorly flowing flathead (no matter how much to modify it) is way high." Tell that to Ken Kloth.. His 267 incher runs a Holley 600 and does pretty good
Like I said, Jimmy, it's just arithmetic. You can mount any size carb you want if it pleases you, and perhaps you can tweak it to work OK, but the cubic inches in the engine aren't going to get any bigger and some fairly-well compensated engineers at companies over the last 100 years have figured this stuff out. You have to consider driveability, unless you just want to run it full throttle all the time. When I was a kid, I mounted a 38MM mikuni carb on a 100cc motocross bike. That thing just screamed but it had no low end power. Full on or nothing, and I eventually blew it up (twice). I see this forum as a place for friendly exchange and friendly advice. Do what pleases you. I won't take it personally.
My computer is down so I'm using my wifes. When mine is fixed I'll try to remember to post some photos. If I don't shoot me an email....
Yes, Terry Please post some pics. I looked on the Flatattack site, but found nothing to do with a dual 4 manifold. Thanks Jim Lou, you're right, no invite, ha ha
Jimmy2Car, I have no idea why you are getting **** over something so cool. Say it doesn't make the exact peak power another set up could, so what. How many flatheads are out there putting around and wheezing through "kewl" looking miss matched aluminum heads making less power than the stock iron units? Some people can't make a standard Holley run correctly... that doesn't mean the rest of us have to be limited to Edelbrock 600's on production intakes.
I don't know either, Algon. Maybe because it's not viewed as traditional, or because some don't have a clue as to sizing requirements for a higher performance engine. The Holley carb site recommends a 600 carb. My max flow IF the engine can use it is 640. Pretty close, I think Have a great Thanksgiving Jim
Jim - one of the differences from the single four barrel Holley 4000 on the 1956 Ford to the dual four barrel Holley 4000 were br*** spacers which Holley inserted around the boosters of the booster venturii. This significantly reduced the airflow on the primary side of the stock 4000's and thereby increased the air velocity, thus the low RPM efficiency. If you have low RPM issues, you might wish to try this modification. Jon.
Jon Thanks. I am aware of the differences between the 2 types, and the uniqueness of the 2. On my engine, the low end off-idle response is nothing short of amazing, revs almost like a 2 stroke. I couldn't be happier. Maybe I just got lucky
Thanks Jim The pictures are awesome and after reading all the posts that thought you were crazy I'm sure glad you ran that setup. I have never found the carb to cubic inch to be anything other than a ballpark calculation. There are people that live by it but after hours on the dyno I have found that every engine has its own personality. That being said I'm going ahead with my carb setup and will see if the engine likes them. I appreciate your help Thanks If you get a chance check out my site pandpvintagerepair.com
Here is a flatattack 2 /4 manifold I have! Just for reference ,it has a 360 dual port iffy top, more detail in his books but it was a record holder and he did a lot of work tuning with it. If I get some time later I will look up exactly what carbs he ran but I believe they were around 400cfm each on a 276 Ci motor.Johnny. And I think your intake is awesome and will run great
Also I believe that baron had a manifold designed and for sale with eight inch runners a while back that could run two fours, it was a successful lakes motor, I pinched their design and made this intake, but never had a chance to run it yet, just needs a top plate change for two fours, also note all these intakes have huge ports for fuel.
Here is a pic of a third intake of mine which I am coincidently putting on an engine this week,it's an offy 2/2 but all three intakes share this port shape designed by Mike Davidson, to get ports this big you need to weld approximately 3/8 of metal around the ports of most stock intakes , the blocks take them no problem
Here's another, this is also a baron as well not the fabbed race intake I was referring to above I kinda copied but what a good looking intake, and then they have that four webber intake
I don't care what anyone says about tradition on a Flathead or any other engine... Dual quads look good on anything and everything. running Holley 4000's as 2-2's under normal running is the same as 2 94 or 97's. Vacuum secondaries only work when the engine needs it and not at the whim of tromping on the throttle. Love it....
Thanks Jimmy6 Somehow this old thread got dredged up. I've had this manifold & carb setup running for the last 5 years without any problems. I did add an electric choke to one carb which made it easier starting. I would add one more, but there isn't room due to the water tubes. I have the carbs jetted exactly like an E code car. Love your setup also. Jim
For some reason guys get all "haywire" on jetting. If a carb is swapped from another engine and the compression ratio is near or near the same it will perform very well. It's an air/fuel mixture deal. Big engines don't need bigger jets as little one needs smaller ones useless there has been modifications to the engine. With that said, fine tuning is always the best thing to do especially with these "out of the box" replacement carbs.
I greatly admire Ken Kloth's work, quite inspirational. Don't know him personally, just what I've read in one publication. No doubt, a flathead V8 can drink a lot of fuel at high rpms. The 2x4 is interesting, vacuum secondaries is pretty smart, well done. Sent from my SM-N910V using The H.A.M.B. mobile app
"I greatly admire Ken Kloth's work, quite inspirational. Don't know him personally, just what I've read in one publication." Ken is probably one of the nicest guys you'll ever come across. Extremely talented machinist, fabulous engine builder, great guy. His record has stood for 28 years. Not likely to be broken anytime soon. Jim
The Jalopy Journal
