Sticking throttle but not a mechanical problem ?

[retroboy]

Howdy
In 12 days time I'm driving 4 hours each way to make my first runs since 1989 but I have a problem and I'm needing a bit of guidance please. I had a  little test drive yesterday to check brakes steering etc on a quite country road and I couldn't help notice my throttle would not return when the engine is running. I have a very basic Mopar small block with a solid flat tappet camshaft. I have a Vertex internal coil magneto that has just been serviced. It has 10 degrees advance in the Maggy and is set on 36 overall. I have new Enderle 80A pump fed by a dash 10 line and a dash 6 from the pump to the injector which is a single 4" venturie similar to a Rons or Enderle single butterfly injection. I have a dash 6 return line and a 3/8 breather in the tank filler cap. When I start it the idle seems to increase as the engine warms but the bigger issue is the throttle will not come back from the highest rpm I hit. The throttle lever is firm to pull back to idle - I sort of think there is a hydraulic feel to it. I have checked the check valve in the return line and it is fitted facing the correct direction and seems to operate with out any sticking. Could a too small a return line cause this?  The cable and butterfly shaft move freely when the engine is not running. Anybody come across some thing like this before?
Cheers

[dreracecar]

Engine off but motor is still warm, back off the idle screw completely, loosen the screws that hold the blade and tap the blade with the end of a screwdriver to set the blade in the bore and then reset idle stop.
 another thing is that you should have to depress the throttle peddle a little in order to attach it to the throttle arm, This is dragracing not F1 a little slop in the linkage is OK

[alkyal]

Is it on gas or alky. It DOES make a difference as to the procedure used to set the butterflies. Gas do when HOT alky do when Cold. Spuds website had a paper that gives a detailed procedure for a beginner. Hope this helps. Al

[BK]

-6 is fine for the return. If the return was too small it would tend to lower the idle because of a rich condition. Along with what was suggested make sure you don't get a vacuum leak when its warm. I had terrible problems with Felpro printoseal gaskets leaking. Changed to a cheap plain gasket problem solved.