Throttle issuses

[manladypig]

I bought a used 1976 fiat 124 (for $1400 so its not in the best shape) It ran and drove and it was able to be driven off the trailer (its not registered so it had to be trailered) and into my garage. I revved it several times to redline and it sounded great. Next day started it up to show my friend how it sounded, went to give it some gas and and about halfway down the gas pedal lost pressure and I let off. Gave it one more go and then a loud snap from the engine bay, at that point I turned off the car. At first I thought it was the throttle cable but then looking in the engine bay I could see it still moved the throttle lever
but it doesn't move the butterfly valve now I don't know much about this but I'm quite sure there is supposed to be a cord right here

So what I'm asking is to confirm for me that there is supposed to be a cord there and how to fix that, if it has snapped, as you can probably tell I don't know what I'm doing and any help would be appreciated thank you

[blazingspider]

There's not supposed to be any cord there, so the snap you heard is from something else. The butterfly valve you see at the top of the carb is for the choke and the bi-metallic spring it is attached to is what opens and closes it and that's based on how cold or hot the outside air temperature is. The spring tension can be adjusted by loosening the 3 screws around that capsule with the 2 hoses. Turning it one way increases the tension and makes the butterfly valve for the choke take longer to open. Lessening the tension will allow the butterfly to open quicker. The long screw your pointing to is for setting the idle speed but ONLY when the choke is engaged.

[manladypig]

Ooooh thank you I didn't actually know what the choke did (I dont know carburetors) Well besides that would you have any idea what that snap was? thanks

[tima01864]

Timing belt break?

[blazingspider]

went to give it some gas and and about halfway down the gas pedal lost pressure

I'm not sure what you mean by this statement. If you're referring to the fact that while pressing down on the pedal you felt the tension give way then I would look closely at your throttle and cable setup for the carb. I believe that the 76 has the cam cover mounted throttle assembly which does have a spring. Could you post a pic of that?

BTW starting a new for you car that's 42 years old and running it up to redline isn't a good idea unless you happen to know the maintenance history of the car like the last time the timing belt, oil, plugs, distributor cap, rotor etc. were changed and when the last valve adjustment was done.

If I were you I would not start the car again. Pull the plugs, get a socket that fits on the crankshaft nut and rotate the engine by hand in a clockwise direction when standing on front of the car making sure you see the timing belt rotate the crank, auxiliary, exhaust and intake sprockets and ensuring it rotates smoothly.

[manladypig]

Quick question, what is the size of the crankshaft nut? if you know I gotta know so I can buy the socket, my socket set only goes to 1 inch. The nut feels about 2 inches but I wanna be sure

[blazingspider]

A 1 1/2 inch socket will fit the crank nut.

[aj81spider]

It's 38 MM. That's almost exactly 1.5 inches (1.496) but it is a metric nut.

I got a narrow socket so I could access it without having to pull the radiator. This is useful if you are just turning the crank and not removing the pulley (on my car you can change the timing belt without removing the pulley, so I just need to rotate the crank).