460 giving problems

[jase386]

72 mark iv, with motocraft 4300 carburetor giving all kinds of problems. Im hoping this time its water, but this thing has been aggravating as the devil for years. Was on my way to a big cruise in Friday to show off my new paint job and vinyl top, and ended up showing it off for two hours on the side of the road instead. (while waiting on a roll-back)

It was running fine until it got hot. Now, the 4300 that i bought to put on it, doesnt have a hot idle valve. But the original does. Does anyone who reads this forum know much about the 4300 Motocraft aggravation carb?

It acted like when an 80s car had problems with the electronic ignition. When i would push the pedal it wanted to die. When i was off the pedal it wanted to die. The only time it would try to run was when i was actively raising my foot off the pedal. Then it would finally peter out. It restarted 3 times, and after that, nothing.

So after a 2 hour break and a ride home on the truck it started fine so i could park it. but i didnt venture out again.

[ericpmarkIII]

Sorry to hear about your troubles. I rebuilt a simuler Carb on my Mark III, 1971 460. Mine also did not have hot idel Comp. Check Basics first- new fuel filter-choke not stuck- links and leaks. That little anti-Diesel Solinoid that halds your throttle at idel can be troublsome, but your troubles sound worse. Possible major Vac. leak. Make sure you have good spark when acting up- old coils, etc. may be OK only if cold. Good luck.

[Fordace]

vapor lock??

pulling at strings here....definitely no fuel....

[ImTheJoker4u2]

distrib vac advance?
+2 on the linkage & choke setting
tossin ideas as well

[Dereck]

Hi

What about some dirt in the fuel pump keeping one of the valves open or a bad fuel pump even?

Regards

Dereck

[gadget73]

Has the carb been rebuilt? Is the filter clean? Have you checked the fuel pressure? Does the motor run hot?

[Steve Moran]

Sounds like accelerator pump is or power valve. Has the engine backfired through the carb lately?
Of course it has, it is a BB ford. :rolleyes:

[ericpmarkIII]

Some more brief thoughts on 4300
You may have an interlock- secondaries locked with chock shut- would hurt preformace if closed- raize hell-lean if they don't shut.
Floats- you may have bad float-stuck vlv/ . My book listed a funkey duel inlet (fuel). My 71 carb had a machined plug for this "aux Fuel" passage. I think I installed the aux inlet from rebuild kit. I digress- was curoius re why they had aux fuel inlets in past- most (Holies, Q Jets) do not. ### Rebuild your carb and I hope you will find it a few hours and $40 well spent- Discount stores may not stock your floats.
Timming- This and many V-8 Fords sometimes run for years with Vac adv. Diaphram torn- Check now, or after carb better (have wife hold steady 2000 RPM, disconect/connect vac line while holding time light on marks). If needed go with (69-71????) adjustable vac can- cheap and a big help when needed/ Good luck-rock on.

[jase386]

and why are none of you close enough to come help??

The carb thats on there is a motocraft core remaned by hollie, the little solenoid is not connected right now, its still on the old carb. it did backfire once thru the carb, thats when i quit trying to crank it and called the flatbed. I thought the filter was changed when i put the new carb on, but i think there may be another filter somewhere that im not thinking about. What im calling the filter is that thing right on the front of the carb, but someone told me there is another filter in line somewhere.. ill look when i get a chance.

the real aggravation is that after the tow home, it cranked like it did show room new. so its either water in the gas, or some kind of heat related issue. the engine isnt running hot. i still wonder if the hot idle compensator has somethign to do with it?

[ericpmarkIII]

Just a few more thoughts- I really do not think it is Hot Idel Comp issue. I/m no mechanic but am Ford guy with simular cars. I do not think Ford bothered to run the hot Idel comp. on many of there own Carbs., at least past 1970 or so. In any event, a 4300 passages (hot idel) look small to me compared with engine and carb. size. Could make you run off a bit- hardly enough to stop you. I have a 76 4350 on my shelf (and may buy a 75 Town Car tommaro..) Those have other stuff like Altitude comp. etc. that could foul a guy up. A 4300 looks easier to me- a float-needle problem could explain all..
My advice is treat trouble in simple terms...Mower or Jagurar, an Ottle Cycle needs Just 1-Fuel, 2-Air, 3- Spark at about the rite time and 4- Reasonable Compression to run. Figure out which of these ya don't have when you have troubles, and fine tune latter. Hope ya get her going quick and cheap-Rock on. PS. The $3 screw in gas filter is what we basicly mean by fuel filter, screws in at carb. change yearly and at any problem is mey unsolisited advice!

[jase386]

i havent gotten to fart around with it yet. ill update when i find the problem. i have so many cars and so little time. This weekend im Taking my 75 GMC Motorhome on a trip to a work rally in TN. so i spent all week making sure it was going to be good for the trip. Will work my way back around to the Lincoln sometime. i hope before it gets hot.

My neighbor told me it might be the thing under the distributor, i cant think of the name, its not a module, but the cylindrical thing that makes it all work, or either its the ignition Coil.

[jase386]

STUCK NEEDLE... a few taps at the neck with a wrench and she fired right up. ive driven her to work, and she runs decent, my idle is high, soi still need to correct that, but she cranks like a champ and runs well.

even though the carb has less than 200 miles on it, its 3 years old and been sitting with gas in it, so im guessing it was sticky in there. Poured some seafoam into half a tank, hope it cleans it out.


thanks for all of the suggestions, i checked most of them out before finally giving it a wack. Checked fuel pressure, new coil, new condenser, new filter, poured gas in the carb, it ran, used gas from the tank, down the carb, it ran, hook fuel line up, no run... so finally tapped it and viola! it cranked.