I went through the same thing on my 57 a few years ago. What eventually fixed mine was I purchased 2 new throttle bases (from Charlie Price) for the outer carbs. I still have a whole shelf full of Holley 94 carbs I tried to run on the outer ends of my 3x2 set up to fix it from drawing vacuum.. The new bases was the only way I could stop the outer carbs from sucking air. As others have mentioned, I blocked off the outer carbs and adjusted the center carb to run correctly first. After that I installed the outer carbs with the new bases and it ran great. It's been a few years but I think I was running 57 jets in the primary carb and 55 in the secondary carbs. I was running a good size Comp cam in it to so I was dealing with low engine vacuum also. It was a lot of trial and error but I eventually got it to run good.

Dan      Kingman Az.      86409

I  have been following this Topic with great Interest. I bought a complete 3 x 2 Setup off Ebay. .Professionally built . Offenhauser Manifold. 3 matched "59" Carbs. Never installed.The  end Carbs have both Power Valves and Idle Screws intact. #51 Jets.  I don't know what Jets are in the Center Carb yet. I have a new Progressive Linkage  from Charlie Price. What is the preferred Base and power Valve setup for the end Carbs? No Power Valve? No Idle Screws? Or try it the way it is now and see what happens? There is only Choke on Center Carb. The Vacuum outlet for Distributor is plugged. Does that only work with the Original Loadomatic Distributor? Currently I have a 4160 Holley with later Distributor. Looking for a little more " Bling" not really better Performance. Stock Engine.

  

Assuming you have a '57 or later distributor, your trips should work. Make block off plates for the end carbs.  I made mine out of sheet aluminum.  Install the center carb and tune the engine to idle smoothly and drive without hesitation.  This will flush out any major issues.  When you are happy, install the end carbs and hook up the progressive linkage.  The end carbs only open at full throttle. 

I had all three carbs stock after the initial instal. I personally had a difficult time tuning at idle and low speed since even with the outer idle screws adjusted all the way down, they were still sucking enough air to make a rough, rich idle. I bought the kit from Charlie that includes all three base plates with idle screws removed in the outer's, and seal up great. no power valves in outer carbs, 51 jets in outer, 52 in the center carb, progressive linkage, 1.5 lbs of fuel pressure, no vacuum advance to a Mallory Unilite dist. Works great for me with 15 mpg

What did You use for a Fuel Pressure Regulator? Most of the Ones I found Online won't regulate down to that Pressure.

  

old car mark, .make sure that your intake ports match the ports in the head.  some if not all of the offy manifolds have small ports. they are also the worst performing manifolds  according to tests made by Ted Eaton. 

A pressure regulator is required if a non stock fuel pump is used.   Those old carbs don't like a lot of fuel pressure. As I remember, Charlie told me to hold it at 3-4 pounds. Check with Charlie.

Mark, my Y measures 283”. I’ve been running a tripower since 2003. I plumbed it with shut off valves for each carb. Ran on the center one initially. I have a 6.5 power valve in the center carb and plugs in the end carbs. Running .51 jets in all three carbs. I had a problem with the rear carb leaking last fall when I was up in the mountains. I could turn the end carbs off and just run on the center one.

  Dennis in Lititz PA

Let's shift gears here a bit. Want to discuss distributors? I have an MSD electronic distributor. It has a vacuum canister on it. I currently do you have it functioning. Been reading some of these comments, and see some of you guys have yours blocked off? If it has a vacuum canister on it ,it should be working, correct? If you have it plugged off , then ,it's not advancing? What do you guys think about this?

The vacuum advance on a dual advance distributor is an economy feature and is not required.  On a street vehicle, it is best to have it functioning but it's fine if it is not.

The problem with using it with older carbs is that the older carbs will not provide the right vacuum signal.  This means that the carb has to be modified to produce a correct signal or manifold vacuum can be used.  Manifold vacuum might require the use of a spacer with a vacuum port or drilling and tapping the manifold if a source for manifold vacuum does not already exist or is not available.


Lawrenceville, GA