Big Block Chevy, Edelbrock Dual Quad system on it... Obviously as you can see the factory linkage is too long to work. I've been looking for hours online...Jegs, Summit, Vato Zone, for either a shorter rod or some sort of cable that I can hook up. All I really need is 2 the two nubs that the cotter pins go through. Need them threaded on the ends so I can just run a threaded shaft between the 2. Or maybe 2 spherical rod ends? Just can't seem to come across anything. To clarify on the pic...the Red line to the left is where the factory rod stops, the Red circle is where it needs to go, and the Red dot on the right is where the factory threads on the rod stop.
Guessing it'd be cheaper to just buy the parts needed than it would be to buy the tools required to do that. Plus if I ever go back to a single carb I won't have to buy another factory style linkage for $40
Get some small heim joints and replicate the set up you have on the progressive linkage. Call a local speed shop. They probably won't have heim joints that small but they can point you in the right direction. My local shop pointed me to a boating supply store. If that doesn't work you can find them on eBay. BTW- I've got the same progessive linkage on my car. If you don't already know, you're set up won't work like that. There's a decent set up guide here: http://www.chevyhiperformance.com/howto/148_0403_dual/index1.html
Buy some 1/4-20 "Allthread" and fab your own linkage... or buy a "Die" and thread the current throttle rod and chop off the excess. Be sure to check if you're getting Full throttle on both carbs by having someone floor the pedal and note the throttle positions on the carbs and loosen the donut on one side and see if you can get more throttle out of each carb. Helps to observe the action of the linkage to understand the proper set-up! I went to a Progressive linkage on my 455 Olds and immediately gained 25% increase in fuel economy without performance loss. Trick is to adjust the secondary carb idle mixture so that it feeds the farthest cylinders away from the primary carburator to avoid a "Lean out" condition. A "Lean out" condition will increase operating temperatures.
The linkage on the carburators was already setup like that when I bought everything. Instead of being progressive with only the rear carb opening, it's set up 1:1. I talked to a couple guys running the same setup and they suggested to run it this way. If it doesn't work I can always convert it to a progressive linkage. Found these on Jegs.com finally... Gonna head down to Lowes and see if they have some threaded rod in 1/4"-28 and make a new linkage. Thanks for everyone's input
On bbc, if you run the linkage as progressive, the front cylinders run lean. When my buddy saw my one to one linkage, he switched his over and now his rod runs 15 degrees cooler.
Use all-thread for the rod and use a sleeve of straight brake line to cover the threads between the connectors. Choice #1 factory type threaded "barrel" shaped connectors (with the cotter pin hole in the stem, like the one on the accelerator pedal arm now). They usually can be found at a real parts store in a catalog or by the brass fittings. Choice #2 lawn mower/ equipment suppliers who sell the ball stud link (called a tie rod by them) in your pic for lawn equipment. Choice #3 Grainger has rod ends and tie rod ends. Marty McF. BTW, I haven't heard good things about the progressive linkage set-ups. Using two carbs originally designed as primaries for progressive dual quad seems to never work out with out a bit of work. Just ask Carbking on here (Jon from the Carb Shop) he has many years of carb experience under his belt.
Dale Wilch has great stuff to fab up your own linkage and the prices aren't bad either. Here's the link to his site http://marketplaceadvisor.channelad...s/deluxeSFshop.aspx?sid=1&sfid=78392&c=613655
Ditch the progressive setup and run the carbs in sync. Throttle response goes up and the car will be much more fun to drive aswell. Half throttle on the pedal means you have already 4 barrels over half way open. Did the same once on a 440-powered motor. Dual 625 Carter carbs. Most fun engine I had driven ever since.
I found some links of "all-thread" or threaded rod at Lowes. It's not quite long enough but I got a couple and some connecting pieces...hopefully be able to figure something out. My linkage is setup to run 1:1, or "in sync". I've heard the same thing from other BBC guys that the 1:1 setup runs much better. Wish I knew of more places locally I could just run down and pick these parts up. Waiting til next week for shipping blows!!
You don't have a tractor or lawn equipment place nearby? They have the very same links and they are a little cheaper than the mega mail order places sometimes. M. McF.
I'm not trying to be an ass, but it's still not right, even for a one-to-one set up. This is hard to explain without pictures but here it goes... For a correctly working one-to-one set up, you need to use the same hole on both carb linkages. The linkage on the front carb needs to be moved from the lower position to the upper position on the carb = so it's the same as the rear carb. What you will get with the set up you have now is this: the front carb is going to open faster because the linkage is attached closer to the pivot point on the carb. This means that the front carb is going to be 100% open but the rear carb might only be open 85%. The rear carb won't even be able to open fully with this set up. The next issue is the brass blocks and the "donut". If you are going to run a one-to-one set up, the brass blocks need to sandwich the donut so no movement is possible. With your current set up the front carb can "blip" independent of the rear carb, the linkage and the foot pedal. I've heard both ways on the progress vs. 1:1. I'm running a full roller small block with a decent cam, I should be making around 390ish horsepower. It took me quite a few tries to get the progressive linkage working but once I got it ironed out - it's awesome. I think it makes the car more docile at part throttle, but it still sings at full tilt.
I see what you mean now. I assumed you were talking about progressive VS 1:1. I played around with the carbs before mounting them. They both seem to open at the same time even the way it's set up now. I'll jack with it some more tomorrow, see if it'll work the way you're suggesting. Thanks for the link earlier too. Great pictures on the linkage setup
The "Service Bulletin" for the '57 DeSoto Adventurer 2X4 engine, also says to adjust the idle mix on both carburetors...and runs progressive linkage...
Very true, and it's not just BBC, either. I run a pair of Holleys on my SBF and while it ran great with straight linkage, the mileage was less than great. I switched to progressive linkage and the thing ran terrible. Hard to start, no power, poor throttle response. I tossed it, put the straight linkage back on and adjusted the front carb's accel pump so there was some slack in it and tried again. I've only driven the car once since then, but I can tell it's MUCH better than progressive and seems to run slightly leaner (better) then with both accel pump arms adjusted how you would on a single Holley.
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