No high rpms now

[Allenk]

I'm working to get my 71t w/2.2L and Zeniths on the road. I'm running 3 psi of fuel pressure with an aeromotive bypass regulator, have checked the float levels, balanced the carbs, set the air flow and roughed in the mixture. The car is a beast to start but once warmed up idles fine and transitions fine from idle via the accelerator jets. The problem is once I try to hold steady rpms at about 4k, the car just starts sputtering and/or just dies as if it ran out of fuel. If I feather the throttle a little I can sometimes get past it but once I do it sounds like a dang Indy car.
I checked the dizzy and it seems free.
All of the warm up set up is gone and plugged.

This thing hasn't been run in a while so maybe fuel pump?

[T77911S]

dizzy free? verify timing is advancing with RPM.

if it has been sitting (or not) perhaps the carbs just need a good soaking, providing you have the mixture set properly.


is the rest of the ignition in good order? its usually a good idea to replace the plugs after a big carb adjustment, they can get fouled.

[daniel911T]

I have a '70T motor in my '69, and I was having the same problem as of last weekend. The car would rev up to about 5k, but it would fall off, then start missing, then give a massive backfire. I thought it may be a fuel delivery problem too, but I was wrong.

For your problem, I have a few suggestions: check out the distributor completely, fresh gas, remove and inspect your plugs.

For the dizzy, obviously, change and set the points (major problem I've had in the past) then try pulling the felt out of the shaft that the rotor is mounted on. Give several drops of oil, and then work the advance mechanism several times. Look down into the dizzy and visually inspect the springs. Are they covered in the crunchy white remains of what was grease 40 years ago? A thorough cleaning is a big help, and not that scary. Here's a link to what I did and saw in mine:
Major rejuvenation of my '69 T see #48-50

After fixing my dizzy, I still had the problem, so I took two actions, and I suspect both were necessary. My plug wires had severe corrosion on the plug ends, and so did the caps on the plugs. A new set of Magnecor wires and some steel wool for the plug caps, and the car magically started running on all 6.

The second thing I did was drain the fuel out of the bowls, take out all the setscrews, open up the progression holes (this is Weber stuff, but I assume Zenith has some equilivant) and pull all the idle jets. I then put all the hardware to soak in carb cleaner, and got to work with a spray can on the carb bodies. I used an entire can of cleaner on each carb. With the bowl drains out, I sprayed quite a bit of cleaner straight in the bottom, to remove any stuff that may have settled. I then stuck the straw thingy in the idle jet holes and let her rip, then I did the same for the air correction and mixture holes. Spraying some down the bowl vent can help a bit, and on my Webers I cleaned out the progression holes (I'm not sure you have access on Zeniths) I did this a few times until the can was empty. Then I did the same thing on the other side.

This is kind of a poor man's carb rebuild. Mine were just rebuilt, but I foolishly exposed them to really bad gas, necessating the cleaning.

If you haven't already, drain the fuel tank, and give it 5-6 gal of premium. That will at least get you clean fuel to work with.

I set the carbs to the recommended initial settings, and it fired right up. It held steady at 6k rpm, and did not seem to starve for fuel. (note: I made no change to the pump, regulator, or anything else)

I really hope this helps!

Dan

[Allenk]

Thanks for the ideas. I need to get out to the garage and get the fuel system emptied and rinsed first I think. I always like to start cheap.

[daniel911T]

Originally Posted by Allenk

Thanks for the ideas. I need to get out to the garage and get the fuel system emptied and rinsed first I think. I always like to start cheap.

Carb cleaner and a tank of gas would indeed be a nice, cheap fix. It also dosen't cost anything to visually inspect in your dizzy, check out your plugs, and set the points. You know, KISS and all.

Good luck!
Dan