Flat top carbs and I need help

[alordzot]

Thanks for the info I have already done the things you suggested. My problem is that the carbs are or seem to be empty of the oil needed in them. The book calls for SAE20 oil to be used. But does not state how much to use. Current issue is that the fuel does not seem to be getting to the cylinders through the carbs. I have good fuel flow through the electrical and mech pumps. So I am not sure if it is just a problem with the oil being missing from the carbs or if the carbs need to be completely rebuilt. So now what do I do.

[kmack]

Zedrally is right. You can get the Flatties to work. I've done it, but I had to disassemble them, clean up everything I could get to, and carefully put them back together. As for his comments that they run better than the round-tops, I have no experience there. I sold the flatties and put in my round tops before I drove the car much.

What you need to do with any carb that has been sitting for over a year, is to clean out every orifice and port that you can get carb cleaner through. Pull out the jet needle and clean it off too. Clean up the piston and all the old oil in the damper. Clean out the float bowl and the needle valve. Also make sure you seal up the float chamber on those carbs REAL well. Otherwise they will leak. Mine did.

Once you've gotten them clean, then they should work pretty good. Like Zedrally said, they are preset (mixture) at the factory. So as long as you don't touch the settings when you're cleaning, it should run when you put it back together. Good luck.

[2ManyZs]

If you can do it legally, I strongly suggest de-smogging it if you plan to run the flat tops. That will help tremendously, and so will blocking off the water to the manifold and carbs.

I had good luck running flat tops on my first Z after I did the above items, it ran like crap until I de-smogged it and blocked off the water.

With a good cleaning and a re-build, and doing the above mentioned items and you should have a set of carbs that are as good as the downdraft Webers IMO.

[alordzot]

Ok I will try it... Should I get a rebuild kit and use it while I have them off the car. An 2manyzs you know that I am in va and if I understand correctly I can desmog the car since it is 30 yrs old.. I guess I need to check with DMV. DESMOGING it. What does that take?

[zerozero]

Why does blocking off the water to the manifold and carbs make them car go better?

[tanny]

Zedrally and/or 2manyzs:

I am rebuilding my flat tops at the moment and was wondering if you guys had any tricks or advice on making these run well. I am desmogging these carbs and was wondering about the vacuum operated accelerator pump. I don't really have any info on how this pump works. Does the vacuum come strictly from the venturi effect in the carb or is there some vacuum line that I need to leave attached to the carb that is the vacuum source for the accelerator pump? I'm removing all water lines and servos etc. and want to be sure not to remove anything that is necessary to the basic operation of the carb. Hopefully you can understand my ramblings, and this info may also help alordzot. Thanks, Victor.

[Alan Pugh]

As Zedrally said if these carbs are re-built to manufacturers specs they will perform very well. As I understand it the mixture is changed by altering the float level and supplied in each re-build kit should be a small cardboard ruler for this very purpose. As far as disconnecting the water from the manifold and carbs goes there are benifets both ways. The carbs sit directly above the exhaust manifold, a great source of heat. Highway driving stops a lot of this heat soaking into the intake manifold and carbs and the water cooling tends to make the whole system run hotter, but get stuck in traffic and the soak time is greater and the water cooling actually woks to cool the whole system and prevent vapour lock. All great in theory.

The water jacket in the intke manifold and base of carbs serves to keep the system at a constant opperating temp which in turn helps to keep the carbs opperating at a constant setting.

Hope this helps and doesn't confuse.

Alan.

[Zedrally]

Originally posted by tanny

Zedrally and/or 2manyzs:

snip

Does the vacuum come strictly from the venturi effect in the carb or is there some vacuum line that I need to leave attached to the carb that is the vacuum source for the accelerator pump?

Thanks, Victor.

Victor, I'm doing this from memory as the car is at home, I'm at work!

From memory the dashpot you refer to isn't actually the acelerator pump. It actually has sometrhing to do with choking.

There is a "U" shape vac line that contects from the top of the carb to the "pot".

The accelerator pump is the round part held onto the body of the carbs by 3 screws.

The rebuild kit contains the rubbers, seals to rebuild these.

Becareful what you remove as far as smog gear, personally I wouldn't remove the water as it has a cooling effect when in heat.

Mike

[Zedrally]

I omitted one thing in the last post and that was those "choke" dashpots where the only thing that I found didn't have a major effect on performance.

In other works if you disconnect them there is no noticable effect.

[tanny]

No, the accellerator pump is what I was interested in because you said it was vacuum operated. I was wondering if I removed the smog stuff this would affect the operation of the accellerator pump in some way by altering it's vacuum supply. I have pulled everything off the manifold(except the egr valve which should stay closed with no vacuum supply) and carbs except the basic carburetor. Obviously I will have to plug some of the vacuum ports and egr openings. The rebuild kits came with the rubber for the accel. pump, gas inlet valve, and various gaskets, but didn't come with any measuring device(cardboard scale or whatever). I did take off the vacuum servo that hooked up to the accellerator linkage. Will be an interesting experiment trying to get these to run if my triple webers fail to improve. Thanks, Victor.

[Zedrally]

Again from memory,

The accelerator pump vac line is internal.

If you haven't removed it as yet from the carb body then you won't see it.

These lines are small are very important to clean completly.

My kit didn't come with a ruler either, I used a dial caliper to check the float level.

[tanny]

That's what I thought. Then my de-smoging at least shouldn't affect the accellerator pump. I hope. I'm not sure what I'll use to measure. I'll have to solve that when I get to it. Thanks, Victor.

ps For some reason, these carbs didn't have the individual choke dashpots that they show in the kit manuals. The slotted lever is there on the choke shaft, but nothing connected to it. One less thing to remove.