Running super lean off idle

[dutchzcarguy]

On 5/13/2020 at 5:03 AM, RS02 said:

freshly rebuilt L28 Flat top engine with E31 head 

Before balancing carbs you have to check all the other variables, you have done that exept a compressiontest. (?) Now i hear you say.. but it's a new rebuild block, yes but people make mistakes. I once asked the same a mercedes driver with a new not working rebuild engine, at first he got a bit angry.. IT'S A NEW ENGINE.. yes i sayd but people make mistakes.. later on it ran and the engine builder had made a woopsie.. my advice is check and double check.. don't assume, just check a list of things that could be wrong. Everyone is blaming the carbs, they could be right but it could be so much other things why the car does not pull..

On the old carbs you have.. rebuild them, use them on your block for testing and later on you can sell those for more than you paid for the rebuild.. you can get rebuild sets easy for them!  good luck!

Mart.

[7tooZ]

I have agree with @dutchzcarguy some. I recently was helping a local owner he drove my car then said wish mine ran this well. I drove his it just seem sluggish. I had him do a valve adjustment and he discovered that he had low compression on two cylinders. So he pulled the head and found the head had a crack and bent valves. They were not closing all the way. 
So if you haven’t, test compression, adjust the valves, test compression again if needed, check distributor ignition system, check timing, check for plugged filter, check for vacuum leaks, check fuel pressure, unhook all of the throttle linkage. Make sure is opening al the way. No binding or stops. Once you are at this point I would mail those carbs to Ztherapy. 
I know it frustrating, but you will find the problem. Them you will love that car.  

[dutchzcarguy]

10 hours ago, 7tooZ said:

I know it frustrating, but you will find the problem.

Yep, be sure to make all the checks.. (and use a serv.manual thats what they are for) 

The day after tomorrow, it was a year ago that you started this thread!  I would also get a bit frustrated, but you have to persevere and be precise in what you do. 

Success, and tell us what you find and pic's tell a thausand words..