Question about 1966 Ford Mustang
HI Guys This problem is continued from the other post I created below which has a a video fo the engine. I cant understand after struggling to get the engine running why the thing runs so high.! I have holley 425 cfm 4bbl vac secondary heat spring choke. I opened the carb to clean it . going thru everything....its a virgin carb that sat for many years and did not need the rebuild actually . I was able to start the car , running it in the garage regularly, not problem but I wanted to clean the fuel system. But I cant understand why it wont settle down. Its basic idle is dangerously high at about 4000 rpm. I my friend told me its not a fuel problem, but air. I am sure it's not a vacuum leak . But the car would not shut down when we completely closed the choke plate. no effect its a runaway. Its a simple carb what could I have done wrong? 1966 mustang stock no smog. http://www.shelbyforums.com/forums/shelby-automobiles-history-related-topics/19712-fuel-pump-failing-i-need-advise.html#post63255 Thx Lawrence
I am not familiar with this Carb but wanted to answer with experiences I have had with Holley carbs. Maybe 1 will lead to solution.
Your friend may be correct about air flow. But anyway, the throttle shaft and rear butterfly shafts have operating levers on one end. Some are pressed fit and some are held in place by a screw. These operating levers can be put on 180 degrees out of time if you have the removable type.
Even the fixed lever type can be clocked wrong if you have removed the butterfly flaps to disassemble the carb to get the shafts out. The screws which hold the butterfly flaps are smashed to prevent them from loosening up. You do not want to have one drop into the venturi.
Checkball- One is under the venturi housing inside the primary discharge.
Metering rods- As metering rods are lifted out of the jets, the taper becomes thinner and thinner to allow more gas flow. If the metering rods fall off their hangers, you have no throttle control.
Secondary-The vacuum secondary has a spring. These are color coded for a certain PSI. Missing this spring will make you lose control of the rear throttle plates. This can be checked with the carb on the car as the springs can be switched for performance adjustment. Just look to see if the spring is missing.
Choke housing- There is a vacuum passage where the housing attaches to the main carb housing. It has a very small gasket. You can have a vacuum leak there.
Pump lever/throttle- There are several mounting holes for the power valve pump lever. These would be where the operating rod attaches to the throttle. If you put the rod in the wrong hole, it keeps the power valve partially cracked open.
Would enjoy knowing if any of these was the cause.
Posted on Oct 17, 2013
You need to set the idle pin. there is a stopper on the throttle you need to screw it back. as it has never been used therefore it has never been set. screw it back until it is at the right revs then lock it off.
Posted on Oct 17, 2013
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Posted on Jan 02, 2017
SOURCE: 1976 Gran Torino motorcraft 2150
Are you sure your idle ports ( size of pinhole) in carb aren't plugged with something? What happens if it starts to die, and you give it a quick squirt of WD-40 , down throat of carb?
Posted on Oct 18, 2008
SOURCE: 1967 Ford Mustang-- idle problem
If I had to fix this, I would use a tiered approach. You have several issues to deal with. 1st- is the engine timing correct (lets assume it is), try adjusting the choke (blackdial on the ffront of a single barrel, turn towards lean) this should bring down the idle. Turn it till it almost dies then turn in the opposite dirrection SLIGHTLY until it steadies out. The engine might shake more now (it did w/mine) so now you losen the 1/2 bolt that is behind the distribibutor. Now that the dis. is lose turn the whole diss. assembily slightly in either direction. One way will steady out the engine, this is adjusting the ignition timmiing. If all that works out you should be golden. Of course there is a lot of possible causes connecting rod length between the gas pedal & carb, vac. leak(through a vac. gauge on it, that will help finding wether or not there is a leak). if this doesnt work repost with results and a vacum reading. I'll check back
Posted on Nov 23, 2008
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