I wanted something for the 260, not too much like the 2x4s you can find and not the $$ of the new 3x2 set ups. I has looked at the efi lower but the conversions were still out of budget so I did this; freeby 302 efi lower (I had to remove it) Friendly local machinist hogged it out for free too. Then add a couple of the old pickup truck coolant spacers. I will plumb them in. Now my plan was to just weld them on but free advice from free machist is to make a plate to screw to the plenum that the carbs can be bolted to. Then I got another 63 260 carb (you could use 500 holleys if you wanted) I will also use pickup truck carbs to donate the required manual choke parts. Right now I am less than $40 out of pocket for my homemade inline 4 bbl. Autolite. I figure with kits, welding, linkage ect less than $200 to have it up and running Whatcha think?
All four barrels sucking all the time might prove to be a bit much if it's a driver. I'd be curious to try those staged 2 barrels off Ranger pickups mentioned in a HAMB thread a few weeks back.
I've got the same parts around the house, and have been kicking around the same idea. I had figured on building a plemum area about two inches high to mount the carbs on, instead of just a plate. I also considered machining a single, really long throttle shaft. I am looking forward to hearing how it runs. Best of luck.
My original Idea was for the same plenum but cutting out the dividers pretty much did the same thing I figured and simplified the project. I realize that all 4 will be opening at once, they are really teeny carburators, probably not over 200 cfm each. And panic, explain in more detail what you are talking about the mixture bias?? It isn't going to be progressive, all the cylinders fedd all the time.
Very cool idea... I was thinking of Weber 36DCD7 carbs but guess you'd have to use 3 for better top-end breathing. These carbs are readily available locally and have mechanical secondaries.
it will, but shouldn't be a problem if you adjust the carbs PERFECT. when I ran alcohol injected VW motors we had crazy mechanical linkage with butterflies that had to open EXACTLY the same or the motor would shake itself apart. had to use shim stock to set the butterflies at idle and then used a couple of custom cut blocks to check them at mid throttle as well. unless he makes an open plenum he will have a less complicated version of the same thing.
Dang Panic, I picture is better that a 1000 words. Am I right that a larger plenum area will minimize this effect?
Revkev- I had the same experience with a VW: damaged linkage=dead motor. I believe a swore that I would never use multiple carbs again... I never took the motor apart, but I think I burned the pistons on one side.
I understand the theory now. I suppose there are forces in play that I don't understand but if the fuel is getting mixed with the air and the air/fuel mixture goes down the hole then the only real problem is how much fuel falls out of suspension and puddles or forms droplets somewhere along the way. It might be a much bigger concern on a high revving engine making serious horsepower but on a stocker running around on the street I don't expect too much trouble with a bias considering the plenum area is about 1 3/4 " deep. Do you think it would be advantageous to make a plenum that was common to all 8 cylinders? I can weld the egr passage shut from the bottom and just machine out the whole thing. Or build a box.
It's an idea, but I'm not sure it would work all that well running the carbs sideways. If I remember right the float pivots on the side next to the inlet. So fuel slosh when you step on it, would change the float level. Also as noted above one side would be "wetter" than the other. I don't know about the size of the 260's carb, even though I had one once. But I believe autolite's were in 2 sizes, 280 cfm and 350 cfm. Also with all of that area gutted out it may stumble at low speeds, running straight linkage. Perhaps it would have been better to make a top that would have kept the carbs in their normal position, and retain the 180 degree design. (Like a couple of logs that feed each side.) Or you could hunt for a cheap dual quad intake and use the 2bbl's with adapter plates. In any case I do like the idea of running a pair of them on a 260, no matter how you pull it off. Good Luck!
would a spacer help counter that? With a spacer, the throttle blade wouldn't be opening into the plenum, it'd be opening higher up the pipe, allowing the incoming charge to disperse a little more evenly by the time it hits the plenum. -Brad
I have heard some different numbers on airflow for these carbs. I even heard there was one over 400cfm that came on 429s. I have a dozen or so and have 4 distinctive different sized throttle bores. The 260 ones are the tiniest I have seen. Fuel slosh may be a problem. I think it might be best to make a plate so I can redo it and turn them the other way if it is a problem running them sideways. I have seen the 2 Holley 4 bbls mounted sideways, the side hung float style too, I wonder how those worked out. I know they won't go roundy round worth a crap. I also suppose it will make a difference which way I set them.
FWIW, The common plenums would be 1, 2, 5, & 6 and 3, 4, 7, & 8 since it's a SBF. I think there's much adoo about nothing here. Panic's picture is spot on, but all the runners are on the same plane & the same orientation so it's mostly irrelevant for a street driven car. Each barrel would be roughly centered over two ports - one for each horizontal, V-pair (1 & 5, 2 & 6, 3 & 7, 4 & 8). While mixture distribution on the progressive 2-bbl in Panic's post #17 above would put the "spillage" lengthwise in the engine, rather than favor one side of the plenum, I could see minor distribution problems with the pair directly under the primary butterfly receiving more (or stronger) fuel-air charge than those under the secondary ports until WOT. There's tradeoffs both ways, but think the differences would be minimal on a street car with careful jetting.
I still think this is a workable idea, but there's another problem: On these FI intakes, the surface where you want to mount the carbs is parallel with the angle of the heads and the motor. On carburated engines, the surface where you mount the carbs is not parallel with the heads and the motor. The carb mounts horizontal, and the engine tilts down at the back. So if you mount carbs sideways on an FI intake, the fuel level is higher on one side of the bowl, I think this makes for an uneven fuel mixure. Or, I'm wrong.
If you get the manifold hot enough the mixture bias is gone, the plenum will take care of it at the velocities you are working with, the float pivot deal is most likely a moot subject as well, an old ford mechanic in our area used to run 3 autolite 2 bbls on a 300 6 in a sprint car and someone said the carbs would work better if he turned them around and he bet them it wouldnt make any difference, he took the time to turn them around and won the bet but turned them back around anyway! I say go for it! (use could use the shaft joining devices from a twin su setup from the british cars, slightly flexible for slight offset but twists the shafts in time....
interesting idea. I have a truck lower and part of the upper I want mount 4 94's on top, but the fuel distribution has had me wondering for a while how it would perform.
That was part of the idea to run the coolant heated spacers, also to prevent icing ect. since there is no heat crossover. I do believe I will make a way to connect the front and rear so I don't have 2 seperate plenums, might help ease tunability. Any Ideas on power valves? Just run 'em and see I suppose but I was thinking some Holley power valves around 3 (or half of what they now have). Any opinions on using the power valve blockers and just jetting up?
There are so many venturi sizes of 2100s I'm surprised you found two that match These are annular discharge carbs too, so signal will be strong. 7 and 8 are your problem children on a Ford single plane with the 154... firing order. A spacer will help, but really I don't think you are going to hurt it any. It will run fine off of one carb since there is no divider. The signal will increase if the other carb is unhooked, and it should be fine with an annular booster, you will just get on the main circuit quicker on it. What are the venturi sizes of the carbs? Its a number like 1.17 with a clock circle around it down on the drivers side front of the carb. On placement, centrifugal force will be pushing the fuel toward the needle and seat. A baffle in each will help some . The 2150s are similar and have a slosh baffle that is made to keep the vent from splilling, if you pull the top off of a '70's smogger you can see what they did, but it is a front to rear thing on them opposite yours. Mounting them as they are is advantageous if you can keep the needle and seats flowing and shutting right when you let off. That is about the only challenge I see there.
These venturis are .98. I can mount them either way so which would be better, to have the fuel sloshing toward the needle or away from it during acceleration? Right now there is a divider, the front and rear plenum areas are seperated by the egr exhaust port. I think a common plenum will be a good thing but if I run these sideways as planned then all 4 barrels will open simultaneously, not progressive.
I have a couple of those in that size and I have been tempted too. I would think that you want to turn them around the other way. The fuel control would be more natural, as your G's decrease the floats would level the bowls on braking more effectively than at WOT where you need the fuel. You can drop the floats as needed to control any slosh at braking, but the needles will be flowing balls out under acceleration because of the natural flow of centrifugal force. As long as you keep the jets covered and don't flood it every time you hit the brakes hard its money. I would try to lose the divider if possible, 7-8 fight pretty hard for wet flow, if it was EFI it would be different because you would be adding fuel downstream of the plenum resonance. If you tear down a few blown up motors that have run single planes you find that drivers side rear corner 7 on other makes, and 8 on a Ford will be hurt. The resonance dictates some kind of balance, your solution is a good one. But I think I would whittle the divider down to let the front carb fill the resonance gap. If you know someone with a flow bench, have him put it on and listen for whistling. That's turbulence. Eliminate it, and I am betting the divider will cause some, and it will be well balanced. As an aside, I used to fool with the Autolite inline 4 they made for the Boss 302. You are on the right track. If you can find some info on one of them, look at the science involved and you'll nail it dead on the numbers.
Do you think I should slide the rear carb back a little to be more directly over the runners of the rear cylinders?
One more thing, firing order makes a big difference. Your LS GM engines and the 351W firing order are the same if you renumber the cylinders, just like the 154 and 184s are the same resonance pattern in the intake. The late pattern puts the two problem children in the front on the drivers side instead of the rear. The main reason for the change was to put the pulses to the mains more evenly, 5 and 6 on the Ford firing on opposite sides of the 2nd main instead of 1 and 5 hitting the front main 90°, or 2-1 at 90° of other makes V8's. To me the Flathead and Y-block firing order is the only perfect one, for both main loading and resonance, as there are really only three patterns for the V8 as it is.
I don't believe it will hurt a thing, and the resonance would be further spread for less turbulence with the crossover there.
I'd keep the separate plenums myself & go with your original idea. But you won't know 'til you try it, really. I'd come down almost half on the powervalves - if they're 7.0, I'd go to 4.0 - as a starting point.
The Carter AFB has the needle and seats in the rear of the carb, they also have a baffle. If you pull the top off of one that would be a good example, because they are like a pair of siamesed bowls like yours, they just have a secondary split. What got me thinking on that was a fellow HAMBer with an AFB problem I just got a PM from, the baffle was giving him trouble and needed a trim. Using a similar baffle could help if yours doesn't already have them. Like Flat Ernie said, you won't know until you try. In testing, if spacers help, then the divider may need a cut.
Great advice. Thanks guys. I haven't got into these carbs yet to see what power valve they are. These are the early design with a drilled passage and a ball for the accelerator pump check instead of the little red diapahram. I have a dozen or so of the old autiloites so maybe I can find a couple baffles. This is what hotrodding is about for me.
Well, I started building one of the carbs ysterday and I can't find any numbers on the power valves that mean anything. Only the one in the kit had numbers and it had 4 digits all spread out 7 5 7 3. I pulled a couple old carbs apart too. I even found one in my pile with a 1.33 on it and some weird huge needle and seat. I think it was like 6 ME or MA. Also I am wondering about ported signal to the distributor, that will change now. How do they do that on multiple carbs that open simultaneously? Should I try to find a vacuum advance diaphram from an origina; 2x4s car? I plan to run the original distributor with a petronix.
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