Mustang Running Rough - Videos

[mphJ]

So i've had a problem develop in the last week or so where the car will start up ok but will run rough, shaking etc, after 10 or so minutes of driving it would clear by itself and run perfect like it always has done, it been gradually taking longer to clear itself as i've been driving it this week, 20 or so minutes etc

So today it's begun to start ok when warm, but when you give it some throttle it will go back to running rough again, see below video links, i've taken the videos of the vacuum gauge because you can get a good idea of the problem

There is some carbon build up on top of the carb, see below pics

It's a 70 Fastback with a 351 Cleveland and Holley carb

Any ideas ? Thanks

https://www.youtube.com/watch?v=nFij7iVA5WQ

https://www.youtube.com/watch?v=Blak1mPGTdY

https://www.youtube.com/watch?v=dA55x65PHNk

[mphJ]

[steveo3002]

carb looks a bit black doesnt it?

[ch427]

Lovely engine that, id start by stripping and inspecting the carb if you feel the ignition to be in a good state.
Is the choke manual or electric?

[Athlon]

Could be a slightly sticky valve although you would hear a tap with that, is it an auto? if it is try capping the vac pipe to the modulator to make sure it isn't leaking. if all good so far stick a timing light on there and check the advance plate on the dizzy is not hanging up.

[It's fixable...]

Centre lead to the dizzy looks a bit dark and discoloured in one of the photos?

First easy check is the coil, leads and plugs plus check the dizzy is properly clamped down and not walking about then check the carb over as suggested by Chuntington.

Is that a mechanical dizzy? If yes check the shaft and counterweights for free and smooth operation. What about the condition of the dizzy drive gear and the bevel gear on the cam?

[daveenty]

Bit late replying here, only just found the post, but the tickover looks high which, combined with your miss-fire, would have me looking for a split vacuum pipe as a first and inexpensive step.