MGB: Engine Idle and RPM questions

I have 73 MG Midget and so far I only have minor problems. Last one was to replace the fuel pump and after that everything runs smoothly.

However, lately I experience some problem with engine idle. Even when I adjust the idle around 1500 rpm, the engine still shakes. When the car is moving, it is fine.

The second problem is that when the engine has been running for a while, the idle rpm goes down (for example from the starting 1500 rpm to around 1000 or sometimes less).

I believe these 2 problems might be connected. Any ideas? Any help will be appreciated.

I've had problems with my 79 also. Much better after finding all vacuum leaks, rebuild carb, adjust valves, adjust water heated choke as per specs. I then started messing with the choke adjusting both ways until it runs best warm. My problem was the choke. Didn't mind going through the rest of the stuff as I just purchased the car and wanted to tune it anyway.
Check the air filter also.
Wish you luck!

I always thought Idle should be at 800 RPM.
I would do a complete tune-up for starters. Points/rotor/condensor/plugs/timing/set carb
Rik

idle should be about 900 rpm on the tach but it will vary abit when on the road.

at 1500 you may experiace runing on or "deseling" when you shut it off.

the guys are right look for intake leaks if it's allover the board esspecially intake manafold gaskets (my 67 midget would go through these every couple years.)

Thanks for all the answers. I really appreciate it.

I had a similar problem. It ended up being my choke wasnt working correctly. It was sending in too much fuel which caused the idle to increase and after driving a while, the mechanism would get hotter and move and flood out my engine, which in turn lowered my RPMS... an easy way to check is to just push the choke down on the carb at idle and if the motors changes RPMs you may want to look into that....