Wedge TR7 Carb adjustment?

[johnrip]

My TR7 engine has been rebuilt. It starts and runs great. After it is warmed up, if I turn it off, and just turn the key, it idles at 900...nice. But if I give it gas, or when I am driving it, it idles at 1600? I dont think the acc cable is sticking...? Any ideas?

 

[poolboy]

That's a big difference. If it were only about a 300 rpm increase I'd say it sounds pretty typical of what the throttle bypass valve will do if it's either out of adjustment or the diaphram surrounding the valve is old and brittle, having lost it's flexibility, allowing fuel to slip past the valve.
Don't go chasing that lead right now though, just keep it in the back of your mind while some others come up with a more fitting scenario...700 rpms..that's a lot.

 

[tr8todd]

Maybe the needle is sticking. Try whacking the carb when it's idling high and see if the idle drops. I've seen dirty or bent needles cause that issue because it won't let the piston drop back into position with the air flowing by. Once the engine is off, the piston drops all the way down and the carbs resume normal operation. You could have a weak spring for that matter as well. Clean the needles and then look down the throat of the carbs to see if there is any difference in piston height at the different idle speeds.

 

[tdskip]

Try whacking the carb when it's idling high and see if the idle drops.

But don't do wild when whacking it

Also, don't go crazy with carb cleaner either since it eat the rubber diaphragm and cause other issues.

 

[Brosky]

Make sure you whack it with a plastic hammer or wooden mallet....not anything made out of steel.....

 

[TR3driver]

Can you get the idle back down by pressing on the lever where the throttle cable pulls? If so, the throttle plate may be dragging on the bore, due to not being centered or excess wear in the shaft.

Not a common malady, just something to look at.

Does your car have vacuum retard?

 

[johnrip]

No vacuum retard. Maybee it should?

 

[johnrip]

It has two carbs, could just one of them cause this?

 

[TR3driver]

Sure, could be a problem with just one carb. If so, you should be able to pull off the air filter box and see that one piston is higher than the other (when it's idling fast).

I doubt the lack of vacuum retard is the problem, was just thinking it might be the source of the problem if it was connected.

 

[mgbmedic]

Check to see if you have return springs. Sometimes they break or fall off.