Well I gave up on the Tri-Power.....

Hey Mutt.....I saved the photo of your linkage for future reference. Did you whip it up yourself? I may borrow the basic engineering to use on mine when I get a little closer to actually finishing it and running it.

 

I had a pair of compe***ion 500 carters on a warmed over 327 back about 25 years ago. It was in a '55 chevy with a 4 speed muncie and a 12 bolt posi rear. The car ran great and still had respectable fuel mileage. I don't know if you can still get the 500 carters but the 500 edelbrocks would probably be about the same carb. You pretty much just change the metering rods to fine tune them. I have always run progressive linkage on all my multible carb setups.
C9 has some good ideas...makes you want to try some different setups out of the normal.

 

Rocky - That's Edelbrock linkage. Works great, and easy to set. The carbs are really foolproof - as I said, just figure the CFM you'll need with your motor/tire/rear/driving style combo, and run them out of the box. Check your plugs, and adjust fuel with a strip kit, using metering rods and/or jets according to the charts they give you with the carb manuel. Make sure you have them set up with the air cleaners you will be using, when you adjust them.

I've got 750's waiting to go on the motor when I add the blower.

By the way, the small 2G two-barrel carbs flow 275 cfm each, which I thought would be plenty for this motor with three of them, but after noticing the car running flat at the top end with tri-power, and switching to this setup and a set of Edelbrock heads, I picked up .5 second at the strip. The old heads were 441x, so the flow is about the same, I just saved weight.

Mutt

 

That is nice linkage on Mutts dual quad setup.
I'll bet that's an engine/setup that responds very crisply when the throttle is whacked.

More than likely the vertical square pieces the rod slides within do the job just fine. I'd thought about making something similar and the plan was to use slightly wider vertical pieces to aid in keeping the alignment. Wouldn't want anything ****ing and binding up although Mutt's linkage doesn't look like it would.

I'm curious if the sliding rods are lubed with anything or just run dry?

I've also thought about setting up a progressive using circular pieces of differing diameters and parabolic curves, but the trouble with that is, even with the primary carb open 1/4, the secondary is going to start coming in unless there is a sliding gadget with a stop.
Maybe it wouldn't hurt to have the front accel pump disconnected, run the variable radii linkage and only have the front accel pump come in when required. Trouble with that is, a velocity sensitive device would be needed. Perhaps driven by vacuum, but then we run into complexity problems.
Hard to beat the simplicity of a well thought out progressive.

Some of the guys running trips with bent wire linkage ought to take a look at Mutts linkage and do some conclusion drawing....

 

In 1962 a friend had a 57 ford 312 ragtop with three speed stick. Bored, Isky cam and 4.30 rear. Kinda salty, all the sbc boys around the area were green in the gills.

I cut up a dual four intake and mounted a single four in the mid section and a two barrel Rockester on each end from a J2.

As C9 spoke, the end two kicked in when the secondary on the four barrel got started. Used a mico switch and solenoid to yank open the Rochesters indexed off the secondary of the four barrel.

Strange looking deal, but worked great. Been outside the box most of my life.

 

C9 - I spray the top rod with WD40, but it's more for corrosion prevention than lube. The horizontal rods are level, and there is no binding since the front linkage swivels as the rear is opened, until the stop contacts the rear upright, then the whole ***embly rises with the rear to become level again. I added a spring to the front to make sure that it shuts quickly, in addition to the dual springs on the rear. Here's a series of pics showing the relation of the angle. Ist is closed - the valve cover fins provide a base point.

Mutt

 

This is when the slide contacts the upright at point of cut-in

 

WOT

 

Pretty neat Mutt.
Thanks for posting the "in action" photos.

Looks like you're running a minimum pump shot on both carbs as well as the idle screw on the front carb backed off.
I'm guessing you set your idle speed from the back carb - which makes sense.

About what does you car weigh?
As well as what size engine and diff ratio?
Wondering about gas mileage.

My 32 - about as aerodynamic as a brick - got 10-11 mpg in combined city/highway with the straight linkage dual quads and big cam (294 degrees adv duration).
Highways it ran about 15 mpg.
And I usually stick my foot in it 2-3 times a tankfull.

With the milder cam (262 degrees adv duration) and a 750 Carter on an Edelbrock Performer - as well as having the carb one step lean according to the Edelbrock charts, the car gets around 11-12 city/highway.
Highways it runs about 16 mpg at 70-75.
The same un-cl***y-to-hell-with the mileage driving technique fwiw.

The highway mileage hurt a touch (in both cases) by the 3.70 diff.
Been thinking about changing to a higher ratio, but the car is so much fun with the 3.70's that I'm not sure I will.

I may have a change of heart when I get to Arizona and start running the long desert highways with the so-called 16 gallon fuel cell that seems to hold about 12 gallons.

It ain't the mileage so much as it is the miles....

 

The car`weighs 1975 lbs with a tank of gas and without me. I now weigh 250lbs. I run a 4.11 rear and 29 in. tall tires. I remove the top half of the windshield to race, but have a full T windshield on the street. The motor is a 406 SBC with hypereutectic dished pistons, which with the 70cc Edelbrock aluminum heads give me about 9-1 compression. The cam is a Summit (Crane) 224/234 Dur. at .050 and .465 int/.488 exh lift, and I use roller tip rockers. The crank and rods are stock GM. It has a B&M T350 that's shifted at 6200 rpm. I use a B&M Torkmaster converter that I got with the transmission - it's really too big, and I'll push the front tires through the staging lights at about 1700 rpm. But I have to keep the car dialed back because I don't want to get into the ten second range, and have to make changes to my rollbar. It's very consistant in the 11.2 - 11.3 range now, and 117 - 118 mph.
It has a home made 4 bar setup on the rear, and launches very straight with no tire spin on 10 in. slicks

I've got an 8 gallon boat tank in the turtle deck, and I cruise on the hiway at about 3200 rpm, IIRC, much too high for my liking. Mileage ****s, but the fun factor makes it worth it. (About 6-8 mpg hiway - I actually get better mileage in town at lower rpms)

Mutt

 

Good stuff.....keep it coming....

 

We gave up on the tri power too, this is better..........


than that.........

 

back to jets. would 50s be good for outers? and what about the center, should it be larger?

 

still have my question about jet size