Zenith Carb setup on a 2.4T questions

[shootmyex]

My son and I have been working on a 72T with a 73T 2.4 engine. The carbs are Zenith. We needed velocity stacks and a few nuts and bolts for the carbs on the engine so I bought a set of used Zeniths for the parts. The spare Zenith's have extra pieces on them so am wondering if they are needed for what we are doing.

Right now we have a problem with not idling. The engine and carbs have sat for several years. I just started pulling the jets and spraying carb cleaner on them and in the holes. Is the jet size in really small print on the end of the jet? Does 0115 mean anything? I've read alot of the posts for Zenith carbs and that doesn't sound like the sizes I was looking for. My thoughts are they might need to be larger by drilling them but can't do that until I get a wire guage.

Can someone tell me what number 1 is and what is does? Number 2 is the idle sylinode but the carbs on the engine do not have that and are actually plugged (number 4). Is that good or bad?



Number 3 is the enrichment valve. I don't have it on the carbs on the engine. Is that good or bad?



Number 4 you might be able to see that they have been plugged, it looks like soldered or JB Weld?
Number 5 are the idle jets, right? Just wanted to check.





The last two pictures are of the insides of the carbs on the engine incase anyone has comments about them.





Any and all help on these carbs would be appreciated. If the parts I mentioned are not needed for my setup and someone needs them PM me. Thanks, Kevin

[project 911]

Kevin-

Maybe I can help a little.

Number 1- I've never seen before, but mine had something similar. It can go away.

Number 2- Most people have removed those and plugged all the
number 4's. Make sure they are plugged well or they make for big vacuum leaks.

Number 5- These are your main jets (they screw in under the bowls right?) 0115 is a normal jet for these.

The idle jets are just below the seam where the top section of the carb screws down. These may be in the 45 - 50 range (number on the exposed end).

I still have number 3 on mine, but I don't think I need it. It is activated by a switch below the drivers side carb. The linkage contacts the switch at 0 throttle.

These things are tricky, and it took me ages to get mine right. I'd say you should clean them like crazy and get some canned air or a compressor to blow out the passages. Also, if you haven't already done it, there are screen filters inside the large bango bolts that connect the fuel lines to the carb body. Make sure they are clean. Rebuild kits would be in order. Check carefully for any leaks around gaskets etc. Some starting fluid spayed around the bases while running will find the leaks. You may also want to check for excessive throttle shaft wear which can make them very difficult to tune.

There is some pretty good information around here on where to set all your needles to get you started.

Hope that helps...

[A Quiet Boom]

I almost hate to say this but MotorMiester was very helpful when I was setting up my Zenith's for the 3.0. I purchased their 36mm venturis and followed thier recommendations for jet sizes. They have some info on their sight. Next #4 should be plugged, you don't need those tubes. you can also remove the other stuff and plug it. #5 are the main jets and the number means 1.15mm the idle jets are higher up near the top gasket, take them out and soak them then blow them clean with compressed air. I drilled my idles to .65mm for the 3.0, I forget the stock size but you might want to go .05-.10mm larger but for now just get them clean. Next adjust the accelerator pumps so they all shoot at the same time. Then open the throttles a bit with the throttle stop screws and synchonize the carbs, I've found a richer idle makes for a more pleasurable cruising range so don't go directly by the book. There are two screws for each idle circuit located near #4 the small screw is the correction screw and the large one with the spring is the mixture screw, turn both of these screws all the way in. Next back out the mixture screws about 3 turns. Start the car and using a sychro tool find the cylinder with the highest reading, leave it's correction screw all the way in, then adjust the others to match the reading of the first cylinder. Oops forgot, when adjusting the throttle stop screws back them out and then move them in until they touch the stop, then go a bit further equally on both sides until the car will idle, do this before anything else. The book says to then adjust the mixture screws for the highest idle and vacuum, I prefer to be just rich of that. As the idle raises you'll want to back out the stop screws to bring the idle back down. Once finished verify that each barrel of each side reads evenly, then adjust the stop screws so both carbs read evenly and take her for a test spin.

BTW I'm going mostly from memory here so double check the book on this, but do take my advice on a rich idle, you'll be much happier and the carbs won't pop or surge.

[A Quiet Boom]

Forgot to add, I'd be interested in a carb body if you'll let one go.

[cnavarro]

#1 is the sportomatic control valve. I'll take it if you don't want it :-)

[austin552]

Here's an explosion if it helps

[nabilious]

I too cut my teeth on a set of Zenith's last winter (3 times before I got it right...patients) Everybody had great advise, cant top that. but something not mentioned that should be (and would have saved me the first two attempts) is to just remove everything you can off of them (take lots of pics) and soak it all in SafetyKleen or some other industrial strength solvent for a good long time (careful, stuff is toxic). save your carb cleaner sprays for the lawnmower. do follow up with compressed air though, bump on that.
now you'll have a clean sheet of paper to start with, no more wondering if dirt is causing you problems in hidden passage ways.
Nabil

[shootmyex]

I'd like to thank all of you that have responded to my questions about the carbs. This past weekend my son and I removed the idle jets, sprayed and soaked them in carb cleaner and then used an air compressor on them and also sprayed and aired where the jets go and what a great difference. After we did this we started it up and it idles now. Now we'll do the fine tuning but it's idling. I will be PM those of you this week sometime that inquired about parts off my spare Zeniths. Thanks everyone.

[cnavarro]

Sounds good! Best of luck with your Zeniths! Let me know about that #1 sportomatic part if you want to part with it.

[trak ratt]

The manifolds are also from a sport-o-matic. Getting harder and harder to find these. If you haven’t even driven a car so equipped they are a hoot, and make a lot of sense for some drivers and situations. Typical well thought out engineering solution unlike almost any other.