popping through the exhaust at 4500 rpm or so.. HELP!

[Zedyone_kenobi]

Yup, but I have had a really hard time getting through to Steve. I have talked to Bruce twice, and he suggested I call the shop, but the shop must be swamped with work. I cannot get any feedback

[Zedyone_kenobi]

UPDATE:

I have thrown in the towel guys. I finally got a hold of Steve @ Ztherapy, and I am sending these carbs into him. He said he will look at them and bolt them to another car to see how they behave on that one. This is it. If these do not come back with some useful information, then I am sunk.

By the way, the straight 30 weight, did nothing to help alleviate the problem. As every SU tuning person can tell you, the oil really only works as an accelerator pump.

I will post more when I hear back from the fine folks at Z therapy.

[Captain Obvious]

Bummer. :hurt: I know you're beat up and I hope they can help you get to the bottom of the issue. Reputation is that if there's something wrong with the carbs, they're the guys, right? I just can't imagine what could possibly be wrong with the carbs themselves.

Cracked body somewhere?

Wrong springs installed somehow?

Wrong needles installed somehow?

Wrong suction pistons installed somehow?

One last question before we all wait to hear back from ZT... Did they always have that lean mid-range from day one when you got them from ZT, or is this something that developed over time?

Anyway, good luck to you and ZT!!

[Zedyone_kenobi]

You see I do not entirely recall when I noticed it first. I do remember that when I first installed the carbs they ran perfectly. But sometime after this became a real issue. Nothing to do now but wait. If it is not the carbs then I am totally confused. Cracked manifold? Who knows

[Zedyone_kenobi]

I do want to give a shout out for the extremely willing and helpful people at z therapy! They rightfully earn the good reviews they get

[Zedyone_kenobi]

UPDATE

Form those that still care, The great folks at Ztherapy called me back and Steve in then shop installed the carbs on his shop car and Said the air fuel was set too lean by a turn and they liked 3.5 turns out on his car but they experienced zero popping at any rpm. He will look at floats tomorrow.

So, the million dollar question is still what would cause leaning out at part throttle that we have not already covered.

The last piece of data left is vacuum readings over the rpm band.

[Captain Obvious]

So, while you were waiting for ZT, did you try a different set of carbs on your car?

[Zedyone_kenobi]

Nope did not want to bug anybody, but I really do not think its the carbs

My carbs are on their way back. Ztherapy said they were set too lean but everything else is fine.

I will gladly pay shipping if anybody wants to loan me some GOOD carbs

[Captain Obvious]

Yeah, I guess that was kind of a rhetorical question in that I already knew the answer. I have no doubt that you would have posted results if you had tried that

I'm also assuming that the "shop car" at ZT was used to test the carbs under load, right? Not just 4500 sitting still, but 4500 at light cruising load...

I've got a set of round tops that I'd be glad to send for a trial, but I made some customizations and they won't fit your car. They're a direct drop-in for my 260, but if you try to put them in a 240, you'll have linkage problems. (Kinda the opposite of what usually happens when you try to put round tops on a 260.)

C'mon folks! Someone has to have a set of carbs they can send to Zedyone to try.

[Captain Obvious]

Also, forgot to ask...

What are you going to do when you get the carbs back from ZT and the exact same problem still exists?

What's your plan of attack?

[Zedyone_kenobi]

Well I fully expect the problem to exist, since technically nothing has changed.

My plan of attack starts off in data collection and then moves to vast sweeping changes.

First

I am going to run the car with 0 changes from how ZTHERAPY gives them back. Report back

Second

Hook up vacuum gage inside car and see what vacuum is doing while the lean out phenomena occurs. Report back

Third

Spray carb cleaner all over intake while running to try to spot leaks or cracks. Report back

If all of that does nothing

And a set of seemingly good carbs do not fix it I am going to go crazy

I am going to pull the head and send it to Rebello for the works E31 setup.

I am going to install a new oil pump new timing chain, new tensioner , new balancer, new crank gears , etc. I will get it running with my SUs, them slap on some webers or Mikunis

Yes I am serious, yes I am ready to spend money. Mark my words, I will fix this

[240260280z]

Try a distributor swap first.