75 Bay type 4 engine twin dell 40 carbs. When I'm setting the advanced timing at 2500 revs 30BTDC. Then take my foot off the gas it goes back down to around 1500 rpm then it takes about ten to fifteen seconds before it returns to 900 idle. Vac dist with hose off and blocked.
Carbs balanced/sync'd and throttle hitting stops properly? BTW it's not unusual for twin carbs to do this
Yeah done that. Seems to want sit at 1600 a lot. Was setting up the dell 40s too and getting black reak out the exhaust now which wasn't there before.
Make sure the accelerator cable isn't too tight either... You also need to get these set up on a rolling road - you can't just bang them on with book jet sizes and expect them to be spot on... They need dialling in for your engine
Need to be able to drive it to a rolling Road garage first Surely I can get it not far off the mark to at least run half decent? It won't even manage a hill. Finding a rolling road garage that deals with older engines/carbs locally isn't that easy eh.
Managed to get the idle to settle & no reak. Will need to give the timing another go at max advance as it struggled to make it up the hill. Carb idle mixture screw out at 2 1/4 turns.
What jets do you have in them at the moment? If it's bogging down, then that suggests the jets are too big!!
The main seems a little on the small side... you might need a 140/150 main, and the idle should be around a 50/55 Is it making any popping noises up the carbs when you try and drive it?
It did pop a bit before I turned the idle screw mixture screws out as they were all different. so they are out about the same approx 2 1/2 turns. More of a pop from exhaust.
