Riddle me this: What would 18 psi do to a set of DCOE weber carbs

[Zedyone_kenobi]

Sounds about right bud.  I think I read all that somewhere.  But not nearly as concise as you put it. Very well done. One thing, the PC rod is perfectly symmetrical.  So it would be 25mm from the base to the collar from either end.  I know you knew that, but in case others are following.  I have the PC rod on my workbench from the last time I took a measurement. I will measure it and post it here.  Have to go wake up the two boys who are still sleeping and begin the 'its time to go to school war'...

 

Edit, while I am at it, I may as well do the Roadsters DCOE45's as well... going to be a floaty day.

Edited May 6, 2016 by Zedyone_kenobi

[Zedyone_kenobi]

just measured, the distance from the bottom of the PC to the collar that was resting on the jet shelf (I like that btw) was 27.71 mm.

 

By that , I would say my floats need to come up.  

[LeonV]

Excellent, looks like we're on the same page.

Out of curiosity, what are your jetting specs for the Z and Roadster?

[Zedyone_kenobi]

Let me find out 

 

roadster jets 45 DCOE

idle jet: 55f9

main jet : 140

air corrector : 160

e- tube : f9

 

z jets 40 DCOE

idle jet: 55f9

main jet: 140

air corrector: 160

e-tube: f11

 

 

 

[LeonV]

Thanks! Post up after the float adjustment and test-drive.

[Zedyone_kenobi]

I am thinking I want to get more F9 E tubes for the roadster and see how they run. OR buy two more F11 and see how the Z likes them.  So many ways to tune these things.  I will get those floats adjusted soon. I spent the week on the bathroom floor trying to potty train my 3 year old.... but I am happy to report we had brilliant SUCCESS!!!!

[Zedyone_kenobi]

Okay been a while since I updated this thread

car has run fine here and there but I am having periodic rough running when I start up with pops from the exhaust and intake 

I went and accurately adjusted the floats on the carbs so that the fuel level was exactly 25 +0/-1 mm.  Car still feels unbalanced  like it's running on less than 6 cylinders, it is very strange, and the periodic popping is still there at slight throttle (say 1300 rpm steady) input.  Car has never acted this way ever. The fuel overpressure started this behavior.

My new thought is when I over pressurized the carbs I may have forced some gunk into the idle jet passage feeding the carb 

The question is how to clean that damn passage if it is in fact dirty. I removed the idle jets and gave them a good spray with some carb cleaner.

 

I have read that you can clean these things with an ultra sonic cleaner.  I may be tempted to try that (as I an use them to clean various gun parts as well. The problem HAS to be in the idle circuit as at idle and slight throttle the mains are not even in the picture.

Here is another piece to chew on. I have the neoprene floats in mine. Standard practice is to get the floats parallel with the carb housing lid when held vertically. However when I did this, I had fuel levels that were 3-4mm low with my clear plastic gage. I had to make it so that floats pointed toward the carb cover by a noticeable amount. So many variables and so little time...

 

Thoughts?

I have been looking for a reason to run some 45's on my car. I wonder if the L28 could handle that and not loose too much Zip in the low and mid range. As drastic as that is, when I run out of ideas, I my last option is to buy THREE MORE webers and see if that clears this up. The price paid is worth knowing if I have a dirty carburetor issue or something else. If new carbs fixes the problem, I can then work on tearing down my old DCOE 40's and either sell them, or keep them as spares.

 

I should also mention that after I shut off the car for the night, I noticed that many of the nuts holding the carbs to the manifold were VERY lose. Having an air leak at the carb/intake interface would cause all of the issues I am describing to a T. I did not fire up the car again to check if tightening those nuts as I was revving my engine in my garage at 8:30 at night for a good 30 minutes.  I think people were starting to get upset.

 

Edited July 7, 2016 by Zedyone_kenobi

[LeonV]

Vacuum leak is the first thought that came to mind. Vac leaks are most apparent at idle, less so at part-throttle, and essentially unnoticeable at full throttle unless it's a huge leak.

I set my floats according to the top-down method, I don't pay attention to how they're actually angled as long as they're all relatively similar.

[Zedyone_kenobi]

I agree, I have been going over my notes, and the more I look at this the more a vacuum leaks seems to be the case. It all fits, and is the only explanation that seems feasible. Occams Razor if you will.

The rough running is mostly at idle and just barely touching the throttle. When you really goose it, the engine spins up. Again, matching the vacuum leak theory. IF it really is that simple, I am going to slam my hand in a door or something, as it would mean I let my carbs come lose on me and never noticed it.  OH THE SHAME... I will report back tonight if this fixes the issue. I really do not want to have to buy more carbs.

[LeonV]

You can also test your clogged jet theory by fully closing each idle mixture screw one-by-one and seeing if it affects the engine.  

[Zedyone_kenobi]

OH that is good.... very good! 

[Zedyone_kenobi]

Well I started the car and it seemed to act the same way, how ever throttle response was much better. I let it just idle there for a few, and it was idling much better. I attribute that to the floats now being perfectly adjusted. I did not do much else, but rev it up a bit, and it seemed to really like the throttle again.  I stopped because I noticed my LM1 wide band was not working. WEll that was weird. I had to pull out the instruction manual on that guy.  AS it turn out, I had it wired correctly, but when I put my fuse box back through the DAMNED too narrow opening in the center console, I bend a fuse holder back and I had no current going to the wide band.. DOH. 

 

Need to get some fresh gas in her and drive her a bit more to see where I am. I am still tempted to try to run 45's on her.  My engine is not a crazy build, and I am running 32 chokes in my DCOE 40's. I do wonder what it would do with more air.