You know, I've been watching this, and has anyone thought that maybe this carb just has a pourus casting? This does happen, which is one reason why it's so hard to find good "rebuilt" master clyinders.
This is also a reason why some other things cast in softer metals (aluminum, brass) can cause extremely hard to diag problems.
And it might just NOT be worth fixing that specific carb anymore. Try another one...and let us know.
Either carb you got will work, the only difference is that the metering rods allow only so much fuel into the air horn to be atomized instead just using vacuum, so it's a little more effiecient. However, if you're jumping around from a 302 to a 460, they did take very different jets; but, they also took different carbs, so you should be fine with the one you have.

 

I gutted the lincoln carb and used all the innards from my old carb and dropped the float just a bit lower.I still had moist venturis but they didnt drip.I had also come across a carb from a very early 80s ford pick up with the 5.0 that was already taken apart.I pulled the venturis just for a look inside and found the the check ball weight under the screw that holds down the venturis was metal in that carb not aluminum like my old carb or the lincoln carb.I ran the truck with the airhorn off to keep an eye on things.Everything was fine but the inside of the venturi was still a bit moist.I swapped out the aluminum weight for the steel one and that cleared it up immediately.That extra gram of weight made the difference in holding that check ball down so i left well enough alone.Idle is much improved,truck idled for quite a long time and after it was shut off no more flooding so im callin it good.Id like a little smoother idle but im only using this truck to haul scrap metal and run around town when its to cold to ride and save some wear and tear on my wifes truck so i can learn to live with it for the couple hundred miles a year i will drive it.My daily driver and the only car i have is a 69 eldorado and i actually only drive it when i take a long trip as i ride all year round here in new mexico.
Thankyou very much for the input guys i do appreciate the advice and suggestions.I hope all this will help someone in a bind.A crack somewhere or a pourous casting like greasemark said had to be the problem.I do live at about 5600 feet in altitude and have found anything with a carb here is a little challenging to get dialed in.Especially trying to tune a car at a midway point between higher altitude and sea level.

 

A little FYI from Denver, the home of way-too-fat-running carbs from the factory. At about a mile up, they run a lot better if you step down about 2 jet sizes and about 2mm lower in power valve ratings. We have the IM240 test here, and I've found from the million carbs that I had to rebuild that that seems to be the best balance between power and economy and emmisions.
One thing a lot of people don't think of is that at this altitude, you need the biggest carb you can get; this is done to get the maximum in air into the engine that you can. Then, if you bring down the fuel, you don't waste fuel and it even improves emmisions.

 

Actually i do have the next 2 jet sizes down.I was going to take a break from the truck for a bit and just drive it.I was planning on trying a jet change.As for the power valve where can i get one that is rated different.I never saw any numbers on any of the ones i have.I have the long double ended power valve.I dont think these are adjustable.
This altitude stuff is still fairly new to me as i am from chicago.

 

Yeah, it can be a pain to get used too. As I said, air is the problem with the OE carb. Your using the smaller jets, and if you anywhere near here in elevation, then use an 11" to 13" (vacuum) power valve, and do yourself a favor and use the single stage valve; the 2 stage power valves never seemed to seat right and last long.
Years ago, I used to have a store here that dealt with old stuff like this. I would start asking around or possibly looking on the internet. It's conceivable that Holley has a section on the parts website devoted to old stuff.
I'm sure you'll find something.
Let us know if you need anything.

 

Am i correct in thinking the single stage power valve is the one that is half the length of the long one i have in there now with the deeper bowl?I also picked up the shorter bowl and power valve at u-pull it just in case.The only thing i did notice about the carb with the shorter bowl is that the accelerator pump is shorter also.It doesnt sit out as far as on the carb im using now.The carb with the shorter bowl and pump seems to be for the 302.Oreilly has the different holley power valves.They are inexpensive so ill see if i can get one to work.I ordered a new gas tank which i wont have for a couple weeks yet so i wont be doing anymore till i get it swapped out and install a new muffler as well.Then ill see where things are and keep posting results.

 

We'll wait to hear. GOod luck.

 

Needed some time off from cars and finally got the new fuel tank installed and dropped down one jet size in carb from a 54 to a 53.Thats the smallest i have.Id like to go down one more jet size though just to try it.A new tank helped quite a bit now that im getting clean fuel.I have a slight hesitation at cruising speed say around 45 mph and was wondering if this has anything to do with the 2 stage power valve and should i go to a single stage and swap the deeper bowl for the shallow one when i make that change?Stands to reason i should.Truck runs suprisingly strong for close to 150 k and goes down the road good.Just need to get it smooth at cruise speed.I adjusted carb air idle with vacuum gauge and the best i can get is between 11 and 12 inches of vacuum.Cant find any vacuum leaks anywhere.
Also the electric choke wire has no power going to it.It should right?Im used to q jets and this wire is hot with key on.I ran a hot wire to it and it works fine so im assuming i should leave it like that.Ford shouldnt be any different.It doesnt run like new but runs suprisingly well for a truck sitting for almost 12 years.Am i being too picky?

 

I believe Ford used a terminal on the alternator to energize the electric choke. Did you check that for power with the engine running?
Where are you taking that vacuum reading from? If it's direct from the intake manifold there is a bigger problem.

 

I agree w/Hanky; 12" of vacuum is a bit low, even at this altitude (it's usually about 16 on a good day here in the mile high city).
I'm sure the power valve will get rid of the performance problem; however, beware of an ignition miss, which this could be describing, especially at this driving style and speed. An ignition miss would show itself as a hesitation under a pretty good load in high gear.
As for the jets, you're just about where you should be. If you went down one more notch, you'd probably notice a slight power loss under load, but nothing really very notible. However, it would have a more positve emissions impact, and it couldn't hurt fuel economy.
And no, I don't think you're getting too picky. Back in the 80's, I used to start up our beater which was a '67 F100 that was given to us for free. Never did a tune up in it, and with the manual choke, it was the only car that would start (with a set of points and carb) when it was -20F. Just don't forget that nothing you do will ever make it run like fuel injection.
But there are times I would still give anythint to drive that old truck again.