Hi. I was advised using this intake on my 59AB was a bad idea since I’d be putting too much carb on the relatively stock engine. I really want to use all carb ports and not block any of these off. Any suggestions or comments? Thanks.
First off, before we can make any recommendations, we need more information. Engine size, cam, porting/relieving, carb type (81 vs. 97 vs. 94), etc. Three Holley 2110's are a lot more than 3 Stromberg 81's.
So just use progressive linkage, with the secondary hooking up really late. Make sure the butterflies in the outer two seat really well.
Stock cam. Likely 81’s. 221 cu in. I may stroke the engine with a Merc crank and change over to Weiand heads. Ditto with a slightly hotter (RV 3/4 race?) cam.
A 221ci 59A? They did make them, but they are by no means common. I think you can get by with 255 ci (bored to 3 5/16") and 81's. on an otherwise stock engine, but I think firming up your plans first may help.
If this was a "replacement 221" cubic inch (3 1/16 bore) 59 series block, then from what I've heard you may not have enough cylinder wall thickness to go to 3 5/16. No matter what you think the block is, I'd have it sonic tested --> 12 spots in each bore --> so that you know what you have to work with. If you're running Stromberg 81's, you should be able to run all three in unison . . . if you're running 97's, you might think about a progressive linkage. It kind of depends on the final cubic inches of the engine.
I was at Joe Smith's speed shop in Atlanta. He did a lot with flatheads and at the time I had a 47 Ford coupe. I spent some time with the engine guy and he said that more than 2 carbs on a street driven flathead was over-carburetion. As he said this I was looking at a car they were building for the boss with 4 carbs on it. He said it was a pretty hot street engine. Then he took me over and explained that while they all looked functional, the end carbs were inoperative. No fuel to them and the manifold inlets were blocked off. They were only there for looks.
I’m not sure you’re looking at this from a cfm perspective. You can’t declare a multi carb system to be bad without looking at the details.
I’m no expert but I do have experience running 2 97s on a relatively stock engine. 2 97s is 500 cfm I believe. 81s are 116 cfm each. So if you were to run 3 81s you’d be dealing with considerably less cfm than the 2 97s which for better or worse is very common to see on a small displacement flathead. So the short story is I’d do it haha.
The old wives tail (tale? ) was always cubic inches of the engine X 2 (327 x 2 = 654 cfm carburetor). There are of course a ton of variables to be considered like cam specs, CR, porting, etc. Stromberg 97's are 150 CFM according to the book. Lets say that the OP has 239 cubic inches, 478 CFM would be a good starting place, a trio of 97's (450 CFM) would be about right...By my crude calculation. I run mine progressive, but that depends on the intake configuration. I sure wouldn't run 3 "big 97's" on it. IMO.
If it is a stock or mildly modified flathead, I still believe that more than two carbs is overkill. Flatheads are not real efficient air pumps.
They were also made after WWII in the 59x series as replacement 221 engines for earlier cats. The primary reason is that many cars/engines were in bad shape from lack of parts/maintenance during the war, so Ford decided to address the situation by making 221 cubic inch versions of their later 59 series blocks. I've never built one, but I've heard they MAY have thinner cylinder walls than the standard 239 cubic inch versions. I always sonic test any block I'm planning on putting a larger bore in.
I've ran dual 97's on quite a few flatheads. Two works really well on up to about a 276 cubic inch flathead, though you probably need 3 or more if you're over that size (especially if you're building more of a race engine). If the OP is going to be running 276 cubes or under on the street, he should consider Stromberg 81's or a progressive linkage with 97's.
The total CFM of a multi carb setup is not simply adding the total CFM together . As I understand it it's closer to 70% of the total . Ask someone smarter than I . Tubman alluded to this on his post .
They're not super easy to find in used condition, though I've bought quite a few over the years. Also, one has to make sure they have all the correct 81 parts (as many seem to have been bastardized over the years with 97 parts). They're not any more difficult to rebuild that 97's as long as you start with good quality cores. If one has the money, going with a brand-new set is surely the way to go!
Hello, As a teenage first time buyer of a Flathead 1940 Ford Sedan Delivery, it was all open road ahead for my surf adventures. I now had a vehicle, the means to make a run to the local beaches and get to our high school on time. But, it was the weekends that allowed me to fully explore our longer road trips north to Santa Barbara area and South to the San Diego region and yes, across the border to the Baja, Mexico surf spots that were relatively empty. The one thing I wished was that the builder/owner of the sedan delivery had kept his 348 motor in place. That is how I first saw the hot rod and instantly, it was going to be my ride. The 348 included cost was too much and after a couple of weeks, the owner lowered his price and said the 348 would come out. at the time, I wanted the full power of the 348. (my brother owned a 348/280 hp motor and it was fast.) but, I settled for the money I had and bought the Flathead powered sedan delivery. Having driven the 348 58 black Impala many times, I knew the power. That sedan went everywhere from sea level to 8000 feet mountain ranges in the snow and dry weather. So, I knew what I was missing. The Flathead was good 90% of the time but, there were several steep hills on coast highway along the So Cal coastline. That gave me problems going up the steep climb, fully loaded with surfboards and gear for several camping days or for longer trips to Baja, Mexico, more food/drinks, etc. By the time we started up the steep climb uphill, within 30 seconds, I had to shift to 2nd. Then climb the rest of the way in 2nd. If there were cars around and I had to spent time in the slow lane, then it was even a 1st gear downshift so we could clear the highest peak of the road grade. Laguna Beach-El Morro Beach, Torrey Pines state beach in the San Diego region, and the Camarillo City highway headed into Los Angeles coming home from Santa Barbara. So, I went to our local speed shop to get pointers on how I could get my Flathead a little more power. The Reath Automotive folks had a complete Flathead motor on display. That was out of reach, so, they said a two carb set up and or a progressive three carb set up with the center carb working 100% of the time. So, it was a two barrel carb on a Flathead motor most of the time. For all around daily driving, the two barrel carb was fine. But, if I had purchased the 3 two barrel carb/manifold, then when the throttle was pushed to full acceleration, then the other two carbs would have kicked in. Simple way to make more power. Jnaki The solution was at hand, but I had to make a choice with the very limited income flow and the full week of surfing South of the border, like this week in the school districts’, Thanksgiving Holiday vacation. So, I opted for the week long surf vacation vs spending the last of the money saved for the three carb addition to the Flathead motor. But, knowing how the three carburetors worked on my brother’s 348 Impala was good and easily adjustable. The progressive linkage could only run the center carb all of the time. we even used it on our6 carb SBC motor build when we were drag racing our 40 Willys build. But, that was set for full throttle of all 6 carbs at one time. Not for everyday street driving. The final thing was my high school friend had secured a three carb set up for his 4 barrel carb replacement in his 57 Chevy Bel Air hardtop sedan. We used the progressive linkage and it worked fine. Two barrel center carb 100 % of the time and the two outside carbs only came on when the pedal was pushed down hard. (throttle response was fully adjustable…) So, the choice is yours. YRMV
A 274 cu inch flathead producing 200 hp at 5000 rpm only has about 65 % volumetric efficiency or 250 cfm
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