After rebuilding the Zs on my 70 T because of two leaky accelerator pumps the car will not run right.It pops and spits out of the stacks and exhaust and is runnig way to fat,even if I turn the idle mixture srews all the way in It still does it!! the engine refuses to idle smoothly if at all and will stay at 2000RPM for a few seconds before idling down.Take into consideration that the car ran like a peach before,the only reason I rebuilt them was the leaks,I figured I should replace all the 35 year old gaskets and o-rings,I think I figured wrong! I have exhausted almost every possible resouce Ican imagine.I have checked everything I can think of including,compression,valvelash,vacum leaks,timing,(the distributorwas checked on a dist machine for proper advance and curve)fuel pressure,and so many other things I cant even remember!!! I have dipped the bodies and the jets in carb cleaner 3 times now with the same result!! nothing seems to make a difference. I have contacted the people at motormiester who are recognized in rebuilding porsche carbs for years,the onlt fault the can come up with is they are dirty or clogged.they were not dirty or clogged two weeks ago before I rebuilt them,see what I mean. SOMEONE PLEASE HELP

 

Sometimes when cleaning carbs, dirt that otherwise was 'anchored' well to the little passages in a carb are released and end up getting stuck in places that are really bad for the job the carb is designed to do. Have you tried blowing the various passages and jet seats out with compressed air? Try putting air through the passages in both directions. It's amazing how sensitive carbs can be to a little bit of dirt. Also, a gasket leak will cause real problems. Are the gaskets seated correctly and sealing right?

 

YES I HAVE TRIED THIS,I INSTALLED NEW GASKETS THE LAST TIME I PUT THEM TOGRTHER.AFTER DIPPING THEM I SPENT TWO HOURS AND 4 CANS OF CARB CLEAN BLOWING THEM OUT TO NO AVIL!

 

popping out the stacks suggests it is running too lean, but you say it is running fat. You've checked everything else, and it is the carbs that changed so I think its fair to say you have a carb problem. I wonder if somehow you have a massive vacuum leak under the carbs that is allowing air in? That would explain the slow return to idle from 2000 RPM. Good luck!You'll beat it.