Gents,
This problem has cropped up recently where, after the motor warms up, it will sometimes accel on its own for a few seconds. It seems more prevalent after time at speed and will occur more often without a load on the motor. For example, with the clutch in between shifts the motor will rev as if floored. It will also do it at idle.

Blipping the throttle doesn't seem to have any effect, so it leads me to believe something in the carb is amiss. I'm dropping off the car to ship back to the States tomorrow, but if it's a quick fix, I'll tackle it. I doubt it will resolve itself sitting on the boat.

Anyone else experience something like this? Help?

Thanks!

In the old days I once had similar sticking issues because the hand throttle cable and mechanism were fouling the gas pedal connections. Also, the pedal shaft can partially seize.
From your symptoms it might be the clutch cable or mechanism binding on the throttle arrangement under the front heater duct.

So I've troubleshot this for a little while now and still coming up with nil. Pulling up on the throttle with the top of my foot does make it stop, but I lubed the throttle cable inside and at every connection. I checked the throttle return spring and all the linkages as well. I even swapped out the throttle pedal assembly because there was some play in the pedal-to-shaft press fit.

It's still doing it only when hot. I'm thinking maybe it's a carb problem, but I am by no means a carb guru. It'll rev pretty good on it's own sometime and rather than drop off quickly if you let off the gas, will sometimes decel much more gently than it should at idle.

It's drivable, but it's pretty annoying and can sometimes be tricky when you need to downshift, brake, and turn, as it'll rev up with the clutch in, and make it harder to slow down and select a gear.

Anybody?

TIA,
Matt

Matt I had a similar problem where the actual throttle cable attaches to the carb on the end of the butterfly spindle. There is a spring there that acts to close the butterfly when you take your foot off the throttle pedal.

Mine only did it nearing full throttle, it got progressively worse over time despite numerous attempts to fix it. Sometimes it would return by blipping the throttle pedal but other times it got to the stage where I would pull up at lights with the engine revving like mad. I would have to nip out of the car and twist it closed with my fingers. I think it was probably the shaft getting stuck inside the carb body. I changed the carb in the end when I rebuilt the car with a spare I had.

I could actually simulate what it was doing by twisting it wide open and it would sometimes jam but not always.

Tony

Tony,

That sounds like the same problem I'm having. That was my next thought that maybe the shaft is binding inside the carb under heat. It's a recently rebuilt carb, so I was hoping to avoid that, but thankfully, I have a spare around here somewhere.

Thanks,
Matt