Quote:
Originally Posted by Burdekin
How have you set the idle mixture? Did it idle nice after you rebuilt the carb and reinstalled it? Did you replace the seal and bushes on the butterfly throttle shaft? What oil have you got in the dash pot?
My 71 B20A specs are 21 to 23 deg at 1500rpm for ignition.
My isolation plate between the carb and manifold was cracked and my spare was also cracked. It idled nicer after it was replaced.
It should idle lovely. I think they will always fluctuate a little with the Stromberg with the carb piston but nothing too much.
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Thanks for your reply. It was a full overhaul kit from Burlen (Diaphragm, Shaft, butterfly, seals, float valve, gaskets etc. plus a new needle and jet. My isolation plate wasn’t cracked but I replaced it anyway just in case with new gaskets. The needle and jet are the fixed type and fitted the needle flush with the bottom of the piston and the pressed in the new jet 2.5mm (100 thou) from the top of the internal surface of the carb. I tuned the carb by the book. The idle trim screw fully closed seems to give best idle results.
The old seals/shaft were well worn and needed replacing anyway. I could have bought the 3 special tools needed but couldn’t justify the extra £100+ for a once off job. I was thinking there may have been an issue with the temperature compensator, I only cleaned it and installed it with new seals without fiddling with it.
Overhauling the carb, 123 distributer, new coil, replacing leaking break booster, new hoses, head off, cleaned & lapped valves, decarbed the cylinders, 2mm head gasket improved the idling but didn’t cure it. The only thing that’s worked is sticking my finger in the hose and like magic she runs smooth and steady @ 700rpm