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I decided because our '53 wagon needed exhaust, it was great time upgrade to dual carb, dual exhaust setup. Got the parts from Langdons and put it all together and had new exhaust put on.

The first problem was both the carb adapters at manifold side, and manifold at carb were both very un-flat causing vacuum leak. Langdon said to file both surfaces and all was well, no more leak after substantial machining.

The car starts perfectly and runs under no load perfectly. It will rev up, never stall or backfire, no problem.

If you go drive car under load it will backfire out tailpipe, backfire out carb, buck, vibrate, ect. It will literally not go.

I checked for more leaks at manifold to head and no leaks. We isolated just distributor with vacuum and also checked it to make sure it holds vacuum. no problem. Also confirmed choke was not on and also have heated coolant running thru manifold.

The car ran perfectly before. Like everyone else, I thought I would be cool and have dual carbs.

Any ideas? I have zero experience with 740s but It seems the mixture isn't right. I understand these carbs are nearly set it and forget it.

Thanks!

There is a reason GM only put one carb on these engines.

Ed

Gosh, if people only did it the way GM did it, this forum would not be necessary?

bigblack'74,

I had those dual Holley-Weber/Ford-740s and they were wonderful (from Tom Langdon).

"set it and forget it"
Luckily I never needed to adjust them. (I just "set it and forget it"; I just installed them and drove with them for 3+ years).
That was good because I would never try to clean/rebuild them.

I sold them in perfect-running condition, installed on my dual-port intake manifold. The new owner's mechanic installed them with the linkages that I provided and they ran beautifully (bolt-on and go).

Then, the new owner's "mechanic" played with them and totally screwed them up. He could never get them right, and he could not find an expert to work on them.

So, just like Ed, I can be of no help.

I checked and adjusted the linkage for each carb and realized one carb was not opening far enough causing a lean condition. I took linkage apart and made the rods exact same length, realigned everything so it was equal and the problem is gone.

I would stress to anyone reading, make sure both carbs and linkage are set exactly the same. I counted threads on rods, fast idle and idle screws as well.

It made a vast improvement in mid to high end power.

Congratulations

The linkage was the toughest part of my install with those carbs. It took me days to get it right, modifying the bell crank bolted to the engine block over and over... I also had to remove the additional spring on the left side of each carb (as suggested in the instructions provided), in order to reduce the force required to open the butterflys. After that I was able to get more "natural" feel at the pedal after finding the right linkage return springs to use. Glad you got it working.

I think a future concern for all of us with these carbs is- where are we going to get rebuild/replacement parts? I have searched and thinly thing that I found was a gasket kit for some ridiculous price, which I am not sure will even fit this exact carb....

If anyone finds a rebuild kit for these, please post your findings!

Dave what did you do for the return springs? My kit did not have any advice on the return spring. The pedal does feel very "heavy" as is now. We use our wagon for trips and that pedal is going to kill my leg.

I also already bought new two spare carbs to keep on the shelf when problems occur.

Removing the circular springs made a huge difference. What you are left with is a very weak spring on the other side of the carb that will barely close the butterfly. Prior to removing the strong springs, my linkage (the one supplied with the kit) was bending under the force required to move it from idle to WOT and my gas pedal was ridiculously stiff, even after making sure that I had all the geometry correct....I assembled the linkage pieces in 4 different arrangements to find the best result that I could get with those parts, then I fashioned up an extra large bell crank from parts from an old GMC that I have in the yard, and then used a couple weak springs that I found at the hardware store. The pic with the spring inside the spring is what I ultimately ended up with. I already had a bracket on my bell housing that I could use to hook the other end of the springs into.

You must add a spring somewhere to the linkage after removing the springs at the carbs, because they don't really want to close all the way to the idle stop after you remove those stiff spindle springs. In my experience, the reason that the gas pedal feels so heavy, is because of the spindle springs on the carbs, combined with the horribly small lever on the other side of the carb spindle that must be pulled to get it to open all the way to WOT- it probably worked great in a Ford Escort with a single carb and a throttle cable with a lot of leverage, but rotating that tiny link with bad geometry a full 90 degrees with the linkage provided is asking a lot.... of course, it's entirely possible that I have arranged everything in a manner that is not optimal- but I could not discover a better way to use the parts provided.

I'm not sure what the original throttle linkage setup was, as mine was badly deformed and rusted when I got the truck, but I decided to make my new linkage so that when the gas pedal is pushed to the floor, the vertical linkage going up to the carbs is pulled "down". That's what I ended up with after juggling the parts around and getting tired of dealing with it.... I might have done something else if I had decided to just start from scratch and build a completely new linkage.

What I wanted was a gas pedal that felt just right, and the carb to go from idle to WOT with as much gas pedal travel as I could get, so that it would be easy to modulate my super duper hotrod 261engine. The result is kinda ugly, but it works great.

Hope that helps. Here's some pics:

Weber linkages

[EDIT] Jeese, all that and i never answered your question....I got my return springs at a well stocked True Value hardware store.

big,

Is that the carburetor that was used on '83-'85 Ford 1.6L engines?

No definitive, but maybe helpful?

1981-1985, at least - Ford Escort 740
http://www.nationalcarburetors.com/cat-fordcar.html

Yes. I hate to say it but often you can get these carbs on eBay much cheaper than Tom, but they still have the solenoinds on them. His are blocked off when he send them. Frankly I like the solenoid. One is anti diesel and one is fuel shut off I think.