Ok
Vacuum leak keeps coming up as a reason for the pilot screws not functioning normally.
This from post #1; " but it starts beautifully'
This from post #6; "It starts on the first half crank. very fast."
This from post #9; "The car starts and runs beautifully. I am quite proud of myself"
This from post #16;"'I saw it and checked it. No vacuum leaks. "
So, if it starts and runs beautifully, but the pilot screw setting makes no difference, the problem is NOT a vacuum leak.The problem IS a faulty standpipe in the pilot circuit. Very probably the engine is getting the correct amount of fuel through the leak. I believe they are related. The standpipe is likely dry and now providing the emulsion air to go with that leaking fuel.
From post #8
"Well there is no way that the bowl can evaporate overnight. So
Your carb is junk. It has a hole in the bottom, and its not easily repairable.When you take it apart look for the hole.Do not put it back together and hope for the best. Look in the lowest part of the bowl, under the mainjets."EDIT or at the bottom of the low-speed well.
When you test for the hole;1) do not use gasoline; its way too volatile.2) do not use water, the molecules are too big and love to stick together. 3) use kerosine, or diesel, or a penetrating oil.The P-oil will wick through just about any crack.
----------------------------------------------------------------------------------------------------
I have a 45 year old HolleyDP on my 367. It runs beautifully. I also have a 40plus year old TQ, that runs beautifully. I have several Carter 2bbls about 30 to 35 years old, that run beautifully. I have tuned carbs that are 40 to 50 years old and worn as can be, and they run beautifully.
Now I'm no carb genius, but it seems to me some guys give up too soon.And I admit ,I havent worked on hundreds and hundreds of automotive carbs. But I have worked on a lot of old carbs,especially in the last 15 to 20 years or so.And that includes multi-carb, and dual throat, set-ups fitted to motorcycles.
I remember one carb I couldnt fix. It was off a Lawboy lawnmower. It was a plastic body. The T-shaft holes were so worn, it wouldnt idle down properly.Who cares, its a lawnmower.Ya pull the rope,ya mow the grass. All its got to do is start and bring the blade tip-speed up high enough to do the job.
Ok rant over.
First, carbs can be tuned to work just fine with a vacuum leak. For example, one called a PCV valve. So, starting and running fine does not eliminate the possibility of a vacuum leak. It depends a lot on where it is, how big it is, etc. Neither does checking for one, since internal vacuum leaks are notoriously hard to find. That also doesn't mean that it isn't a leak in the standpipe of the pilot circuit, because that would explain it too.
Second, do a search on this forum for Carter's with dry fuel bowls. Or hard starting Carter's, or bowl vents, or vapor lock, or whatever. You will find that there are dozens of threads regarding both Carter's and Edelbrock's having the fuel in the bowl's evaporate through the bowl vents. Mostly 4 barrels, but some 2 barrels as well. I know because I've done those searches myself to figure out why I have that issue with the Carter 650 on my Challenger, and why I've had it with two completely different Carter's on the same engine. And an Edelbrock brand new out of the box on a completely different engine in a completely different car. Again, I'm not saying this is absolutely the issue in this case, but it
is a possibility. Keep in mind that in Canada you don't typically see 116*F temperatures, or overnight temps that stay in the 90's. Expected high in Scottsdale today is 111*F. Might have something to do with it.
Finally. You seem to assume that you know more than me about carbs, and that may in fact be the case. But that doesn't mean my input doesn't have value. There's a limited amount of info that we've been provided, and usually on the internet it comes down to how well something is explained. There's a lot of variables, and only one person here has actually seen or heard the car run. When I say a car runs "well" it might not mean the same thing as when you say it, or the OP. I've had people tell me that an engine with a completely dead cylinder "runs fine". And no, they weren't trying to rip me off, they just honestly didn't know.
I also have tuned plenty of different carbs and have done so for over 20 years. No, I am not a carb "guru" and wouldn't claim to be. But I can sync a pair of single barrel SU HD6's with nothing but a piece of fuel hose and a screwdriver. I've tuned SU's, Mikuni's, Keihins, Webers, Carter's, Edelbrock's, and Holley's. Some on multi-carb cars, some on multicarb motorcycles. Everything from single, single barrel set ups to 4x1's, and of course 2 and 4 barrel carbs. I've done so using tools as simple as a piece of hose, a screwdriver and a plug wrench and as complicated as a wideband A/F gauge. And I also have a couple old Carter carbs that run beautifully. And a couple of edelbrocks. And a brand new Holley Ultra 750 DP. And I have absolutely made mistakes tuning all of them, and probably still have a lot to learn about each and every one of them. Typically, when I offer advice or make a suggestion of something to check, it's because I've personally experienced that issue. Or at least an issue that has similar symptoms as described by the person posting about them, which usually gives a pretty wide range of possible issues.
