car stumble and backfire when accelerated!

[Cali71z]

Ok! I check my alternator and its a 12v 60a alternator! I believe it's a 280z or 280zx alternator? The previous owner Bridges the connector where it suppose to plug into the voltage regulator! He jump two wire for the light and one wire on the connector back down. I don't know if that's right? I don't see any wire coming back from the alternator to the battery! The only wire that's connect to the battery is the big red wire from battery positive terminal to the starter motor. Any one have the charging system diagram to convert external to internal voltage regulator for 1971 240z?

[SteveJ]

It sounds like a PO did a swap for a later model alternator. Here is a link to the alternator swap for a 240Z: http://www.zhome.com/ZCMnL/tech/280Alt.html.

[Cali71z]

Thanks! I'll try that converting!

[Cali71z]

OK! I have fix the issue! It was the alternator! The previous owner wire it wrong and it did't charge my battery so the car was only running on battery with nothing charging it. With that issue! My MSD ignition set didn't have enough juice to run properly. Thanks to all ya help! Now if anyone can tell me where's the idle screw for the Mikunis? so i can do my timing or can i just have someone rev it to 3000rpm?

[Travel'n Man]

Now if anyone can tell me where's the idle screw for the Mikunis? so i can do my timing or can i just have someone rev it to 3000rpm?

Have somebody hold your RPM's at 3000. If you are running triples you really need to get a wideband to know where you are. Lots of recent posts on this topic.

[Cali71z]

Thanks for the info! but i would like to adjust my idle, it's setting at 1200-1300 rpm. Any one help!

Edited April 22, 2012 by Cali71z

[Cali71z]

OK! i adjust my timing at 3000 rpm with 35 degree and at idle it's showing 20-22 degree is that right? I think i did it right? Anyone help?

[beermanpete]

If the idle speed is still to high the base timing will seem too high because it is still advanced some. Did you get the idle speed lowered properly?

[Cali71z]

Thanks! I forgot to check the idle speed! yup i believe it set around 1200-1300! I still couldn't figure out how to adjust the idle! Any help well be appreciate! But i'll do more read and hope i figure it out some day!

[Zedyone_kenobi]

Odds are your carbs each have an idle speed screw that adjusts each carb independently of each other. You will need to resync the carbs carefully. Which from the sounds of it you may not know how to do. You need to find an article on setting mikuni carbs up for the first time and do that. It will require patience and a flowmeter.

[Cali71z]

Thanks! I have been reading and have fix my issue! Car is running strong now!

[LeonV]

Thanks! I have been reading and have fix my issue! Car is running strong now!

How did you fix it, it would be nice to know.