Thread: Low idle speed.

I have just done the final touches to my series 3 2.25 ltr, to get a RWC in Qld. While a friend was over doing the timing. (According to the Haynes Manual. He is also registered to do RWC)

We couldn't get a smooth idle. It sits at 500 or at 900 rpm but wouldn't sit at a constant 600 to 700. We used the idle screw to increase the speed but every time I would turn the screw it would be rough then go back to 500 rpm.


Any ideas? It is also a new zenith 36iv carb. and new fuel filter, and pump.

Originally Posted by Blknight.aus

The idle setting is done with the vacume advance disconnected,

if your still having problems when you put it back on apply a touch of choke.

If that fixes it then thats that, Its how I always did mine.

Dont forget that the Idle is set with the engine at full operating temp use the choke to lift the idle from 600 to 900 while its cold.

If its a fresh engine or a really old one thats been sitting for ages, let it bed in/warmup, take it for some good hard work to heat it right up and then do the adjustment.

These motors run quite cold......and often the thermostat can be swapped for a new one that remains fully closed till it's meant to open ......often changing from the "Cold" thermostat (72 Degs) to the "Hot" one (82 Degs) helps low speed running and correct idle.