mcfly94 169 Posted May 17, 2013 Hey guys last few days the 250 has been doing some wierd shit with its running. I rebuilt the webber probaly 7000km with a major kit. Its a good running engine (before the manifold), dosent blow smoke etc.. has a fully overhauled head (larger valves), new fuel pump, new leads, new dizzy rotor, new water pump, new thermostat and housing, so yeah good oil pressure temps, never over heats, you get the point. Problems im experiencing is tuning and how it runs. I set the fast idle screw and get it to idle up around 800rpm in neutral, then set the idle mixture to when it just hits max vacuum. Drop it into D and it comes down to like 350/400rpm, leave it for 15 minutes go back out and start it and the idle rpm in neutral has dropped to bloody 400rpm and in drive its about to conk out, well it would if i didnt keep the petrol pumping. As far as im aware i dont think its vacuum line, everything is hooked up and whats not is plugged off. Trans is c4 auto if it matters with std 6 converter, modulator line straight to front vac manifold source. I think its either the carby, maybe the dizzy/coil, or somehow vacuum line setup, or possibly the converter speed may not be correct and playing a part in the rpm dropping almost by half when engaged in a gear. Hope you guys can guide me in the right direction, its my daily driver and need it fixed asap! Share this post Link to post Share on other sites
mcfly94 169 Posted May 17, 2013 What should the car be idling at, vac reading at idle. How much should the rpm drop by when going from neutral to park. Share this post Link to post Share on other sites
revhead 1,392 Posted May 17, 2013 i thought autos idle was set at 950rpm on idle also you need to take into account the size of your cam if not stock as well. Share this post Link to post Share on other sites
jamie247 542 Posted May 17, 2013 just fuck it off and buy a 351 2 gromet88 and revhead reacted to this Share this post Link to post Share on other sites
KRUPTOR 929 Posted May 17, 2013 Best way to adjust the mixture screw is to have it idling at around 800-900rpm and then slowly screw the mixture screw inwards not to stall but going to stall and then slowly unscrew it till it will rev at its highest and stop unscrewing it there.You can unscrew it alittle and then screw it back in and you can observe the difference in the idle.Then readjust the idle stop screw.Also check your timing aswell,adjust if necessary.I would also check for vaccum leaks around the carby and the intake manifold gasket. Share this post Link to post Share on other sites
xeeclipse 37 Posted May 17, 2013 Have you checked the idle stop solenoid for operation? Share this post Link to post Share on other sites
xeeclipse 37 Posted May 17, 2013 Idle stop cuts fuel to the idle circuit. Your car is only running off the progression ports and the lean mixture is what causes the poor idle. Kicking the accelerator pump cam in the guts is the only way to keep it running.......been there done that Share this post Link to post Share on other sites
mcfly94 169 Posted May 18, 2013 yeah its not the idle solenoid, i know when thats not connected haha, dosent run what so ever. Ive retuned it and its running and idling much better, set it to 700/800rpm in drive, only thing is it revs at 1100/1200 in neutral. cant find any leaks either. Share this post Link to post Share on other sites
KRUPTOR 929 Posted May 18, 2013 yeah its not the idle solenoid, i know when thats not connected haha, dosent run what so ever. Ive retuned it and its running and idling much better, set it to 700/800rpm in drive, only thing is it revs at 1100/1200 in neutral. cant find any leaks either. Is the choke flap fully open??Is the choke working?Make sure the adjustment is good aswell. Share this post Link to post Share on other sites
mcfly94 169 Posted May 18, 2013 Fully open so it never closes choke dont work cause I dont have the alt 9v supply Share this post Link to post Share on other sites
KRUPTOR 929 Posted May 18, 2013 Fully open so it never closes choke dont work cause I dont have the alt 9v supply On mine i run a 12v supply lol. Share this post Link to post Share on other sites
mcfly94 169 Posted May 18, 2013 Tried that but the choke didnt close at all, nor start opening in any postion after removing 12v maybe I need a new choke? Share this post Link to post Share on other sites
xeeclipse 37 Posted May 18, 2013 few gaps in your understanding but you definitely know more then me at your age.....Read much street machine Mcfly94? I'm a street machine mechanic 80% of the time lol! Share this post Link to post Share on other sites
mcfly94 169 Posted May 18, 2013 Nah not really only when theres an xf in there haha Share this post Link to post Share on other sites
Falcman007 100 Posted May 22, 2013 shove a holley on it. great carbs that the 250s love! 350 will do Share this post Link to post Share on other sites
mcfly94 169 Posted May 22, 2013 Got my choke working perfect of 12v on the ignition! However im still really lost on the idling? surely the revs shouldnt drop 500rpm under load? its a bit harsh going to park to reverse because of the bloody idle. 1200rpm to 700rpm Share this post Link to post Share on other sites
gerg 10,871 Posted May 22, 2013 Maybe you could set the mixture while in drive? Maybe squirt something flammable down the carby at idle in drive and see if rpm comes up. WD40 works. Aerostart is better Are you 100% of no vac leaks? Brake booster ok? Pcv doing it's job? I had one on mine recently that was leaking too much at idle. They get carbon in them and stick open, causing too much air to be sucked in. Pull it out and stick your finger over the end. Rpm shouldn't drop too much. Share this post Link to post Share on other sites
