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As I indicated earlier, I took my carbs off and have been going through the linkage bits to ensure everything is working properly. Besides discovering that my carb heat tube was completely plugged I found that the Nylon bushings of the bell crank were super snug on the support shaft. I had to pry the bottom one off, its like they shrunk down over the years. I ordered some new ones from MS and they turn like butter.

Ah I see, I didn't know they were solid, that makes a big difference! Yeah I hear ya, with all of the fuel entering and leaving and the car going up hill/down hill over bumps, idling, accelerating, banking, etc. it's a wonder a float system works at all !

It's the sealant that worries me in a long time gas environment.

Not sure how one would bond a weight to the plastic float in that environment, but its worth thinking about. I like the redrilling idea, but I don't think the "towers" would need trimming down unless they interfere with the movement of the float.

Yeah perhaps, but the new valves behave just like the old ones I took out. I couldn't get the long legged cap dialed in with the old tall valve body either. I just find it interesting that to get the correct gas level in the glass bowl required that the black float be nearly touching the inside of the cap. If I were to use the static 12mm, 16mm inverted lid method I'm sure that there would be insufficient gas in the bowl during acceleration (stumbling). Those numbers might work if the needles were solid and not internally spring loaded. IMHO, the spring loaded 3 part needles are just not designed for an inverted static setting. Does anyone know if the original needles were spring loaded, or were they solid ?

Well, I'm back at setting the floats and have fitted them with some new valves I ordered. I'm still using the glass jar setup, but I've eliminated the water pump arrangement and have a small funnel attached to the inlet port by means of some tubing. The glass is marked at 21mm as a reference and I can poor gas into the funnel and watch where the level stops. I was able to get the short legged cap set to stop at 21mm with the black plastic float about 1/8" from touching the inside of the cap when inverted, however, the long legged cap with the taller valve could not be adjusted enough to allow the level to come up to the 21mm mark. I stopped when I noticed that the tang was bent so far in that it was contacting the body of the valve when inverted and the plastic float was hitting the inside of the cap. I ended up using another short valve body and bending the tang up so that inverted the float was about 1/8" from touching the inside of the cap and that put the level at the 21mm mark. I think this is where I'm going to try them.

I agree with you that it does get worse with worn or dry bushings (I think I said that), but I'm guessing many folks here also set their idle RPM higher than they did at the factory. If you're setting the idle to 1000 RPM its too high IMHO, even the E-Type guys with tripple SU's and a 4.2L set their RPM down around 600-700. Also, I think the bushings used in several places are Nylon which is known to produce stick-slip behavior when dry. So combine dry nylon bushings, with higher than necessary idle RPM and you get an initial sticky throttle press. Before I took my carbs and linkage off recently I had the sticky throttle issue. Now I'm in the process of putting my carbs back on and plan to do some experiments and see if what I've been thinking is true.

I still believe the problem is that the manifold vacuum is helping hold the butterflies closed at idle, its just the nature of the design. The carbs have a mechanical advantage over your foot so it doesn't take much resistance on their part to increase the effort it takes to press down on the pedal. What makes it worse is the force of your foot and the resistance of the butterflies causes the linkage to bind in-between, especially at any dry rotating linkage points. You should be able to test this with the engine off by having someone hold the butterflies close right at the carbs and see if the pedal doesn't get a lot harder to press down. My 2 yen.

I was thinking lower than that, more in the 500 - 600 rpm range. Not sure what the manual says is correct but I don't think there's any harm from idling "too" low.

So I created this apparatus to help set the floats accurately and now I have even more questions. To achieve a gas (water) height 23mm from the inside of the lid the float is nearly contacting the inside of the lid, that's doesn't seem correct. Its that way on both lids and floats. Some assumptions : 1. The gasket and the inside depth of the lid adds up to about 4mm. So I marked the outside of the glass at 19mm. 2. Water behaves similar the gas for this test. 3. My valves are correct and in good shape. Since I have them apart I thought I would use my calipers and calculate where the top of the gas is relative to the carb bridge assuming a fuel height of 23mm. Here's what I got : The bridge to the dome surface is 44mm The top of the float bowl to the top of the dome surface is 33mm So from the top of the float bowl to the bridge its 11mm Add 4mm for the gasket and lid and you get 15mm from the inside of the lid to the bridge Subtract 15mm from 23mm and you get 8mm, not 10mm as I've seen elsewhere ? I'm thinking I should replace the values anyhow, where's the best place to get a proper set ?

Yeah I had read that one, that's where I got the idea for the clear bottle, which I think is a genius idea BTW! Thanks for ferreting out those numbers, until I hear otherwise I'm using them for my 72 carbs

Thanks for the quick on point response! What's the title of the thread from July ?

I have a 72 with 3 screw SU's and they have the long and short arms in the float bowl lids. Long in front carb, short in rear. I intend to set the floats on my bench top by setting the lid with its float and gasket on top of a small clear drinking glass with a 23mm scribe mark at the correct spot. Can anyone tell me whether the distance between the inside of the float bowl lid and the top of the gas is 23mm for both the front and the rear carbs on a 1972, or is the front 23mm and the rear something less ? I'm looking for a definitive answer for myself and all my 72 brethren

It's understood that the mechanical linkage isn't ideal, but I can't believe they would have sold the cars new with the linkage as jerk inducing as I've experienced or a lot of people wouldn't have bought them after a test drive. Do any of the early Road and Tracks or other publications talk about the jerky throttle problem ? Not sure, but I don't recall having ever read about it. I don't think that worn linkage is the problem, like most people I've over lubed every friction point in the linkage path and still no joy. I've noticed that the accelerator pedal resistance problem occurs only when the engine is running, if the engine is off the throttles open easily. With the engine running it takes more force to crack the throttles open than it does to rotate them from there on, even when you use your hand to move the linkage at the carbs. I think this is just a function of the throttle plate design in that the manifold vacuum is trying to hold the plates closed at idle, so it stands to reason if you reduce your idle speed the problem should be reduced since less vacuum is being created and therefore it will take less force to overcome it. I currently have my carbs off for a servicing so I can't try it myself yet, but I think idling your engine down should have a positive effect.

I bought some of the Pontiac Blue at O'Reilly's and later the same day saw some Krylon "Bahama Sea" at another place and bought it as well. When I got home I sprayed a couple of shelf brackets with both paints and compared them to what's left of the original blue on my block and other bits, I went with the Bahama Sea. To my eye in direct sunlight it's much closer to the original than the Pontiac Blue.