Weber dcoes issues. I am stumped.

[spyder]

What's it do minus the air filter , cause " that's some weak sauce " Aquafina
foam filter ?

Who are you asking? If me than it's an ITG filter. When I got mine working cats meow I thought great, now mount the filter. The carbs have a jet block vent pointing twards the air filter baseplate. I drilled 2 holes in the baseplate and plumbed the jet block vent into the filter. Ran poorly after that. Removed the rubber hoses that carried the jet block vent into the filter and blocked the holes into the baseplate. Car ran as before. My conclusion was the intake airflow pulses were affecting the jet block vent intake.

[Gregs672000]

I hear you Spyder... it's pretty hard to diagnose from a distance. 0 full pressure suggested an issue, but I do agree it doesn't bark out of the carbs as hard as I would expect if it were super dry. However, it could be that the fuel level in the carb is low enough that the systems just aren't working right, but again it should do fine for a short time like you said and then get progressively worse as the pump fails to refill the carb. An inoperative accelerator pump system would not keep it from running if you were nice to it, and thus why I asked if it could be reved up slowly. Sharp throttle stabs should make it backfire hard out the carb if suddenly lean, and certainly needs to be assessed. I'm still wondering about the ignition timing... my car could still idle and drive with plug wires crossed, and it acted similarly to his. I drove it 80 miles like this on a new motor as a kid! Regardless, the pump in the bay is just asking for failure down the road so he's gonna change that. Flow balance looked good on the video, so it's either not getting fuel or the ignition is screwy.

[spyder]

"Sharp throttle stabs should make it backfire". Mine dosen't backfire as I am running it ot of fuel however it will occaisionally ping / knock as it gets lean if I don't dial back the timing knob.

[srfjay]

Thanks guys . I know hard to diagnose over the internet. But simple little thinks to check i might have overlooked always helps.
I should have the parts here today to rebuild fuel pump. That would atleast take away a fuel pressure issue. I did buy the carbs used so maybe a rebuild is in order if all else fails. And yes I am also thinking it could be the distributor installed wrong. Even though I tripled checked everything. I know sometimes could be something missed.
Once I get the fuel pump done will update.

[Gregs672000]

You bet, no worries, keep asking. I'm very familiar with these type of carbs as are several here, and we will be able to help you get it sorted! After all this, you too will have more knowledge! I'm really glad you have a wideband... makes all the difference and will make it fun to tune.

[redroadster]

That setup is like a ventury for every cyl so at idle the jet / flow is tiny, id try a block of foam to choke the carbs and open the throttle slightly

[srfjay]

Update. So I installed fuel pump and now has a non return setup. Sadly same issue. The moment I give it gas it runs it goes lean. No matter if I floor it or gentle press gas. Made a small video of what I am talking about. So now I assume it is either the carbs have a issue or something with the ignition. I am going to mess with the spark wires today just to make sure the order is good. It is a brand new east coast distributor set up.

[srfjay]

And did a compression test today. Dry numbers are 152 152 154 155. So that should rule that out.

[Bwk2000]

So, compression is fine, ignition and cam timing are correct, no vacuum leaks found, distributor working correctly, plugs are not fouled, plug wires good, fuel/filters are new and fuel pump is … pumping

All seems to comes back to the carbs. So, is it a ‘settings/tuning’ issue or a ‘component failure’ issue?
Start with the one that doesn’t cost money I always say. Review the links below and see if it’s a tuning issue or troubleshooting step you missed. If not, might want to go back to my previous post with the ‘how-to’ on what to look for while rebuilding these Webers. These guys below know a hell of a lot more than I do about Webers (or any carbs I would expect). Might consider contacting them to discuss your issue … Who knows? Might be as simple as re-jetting.

https://www.carburetion.com/troubleshoot.htm

https://www.carburetion.com/Weber/adjust.htm

https://www.racetep.com/manufacturer/ca ... carbs.html

[srfjay]

Yeah I think I am just to give them a rebuild. I did get them used. And checking those links now. I used some of those videos to tune. I got them synced well and afr is good at idle. So wont hurt to rebuild them just to check it off the list. If that does not work it is cursed.

[srfjay]

Did some more tuning. And I noticed that when I give it throttle it seems to be in a good afr range. But on deceleration it automatically leans out. I remove throttle and goes lean.

[Bwk2000]

So throttle response and acceleration are fine now? If so, great! Now try the low speed/off throttle tuning (see link):
P.S. As they mention, double and triple check all your linkages before you start.
P.P.S. If it’s running well now at 2K RPM, you might want to redo the high speed rebalancing of the carbs before you move on to low speed tuning. Also, if you’re thinking of trying new jets, I would consider increasing your mains to 145 - 160 range and your air correction to 200 - 220 range based on you running 40s


http://www.webercarburetors.com/ppw/htm ... ical_i.htm

[Gregs672000]

It's important to understand how these carbs work and what system does what. Basically you have a float chamber; a slow speed fuel system with an idle circuit; a high speed fuel system; and an enrichment system. Fuel and air mixed flows through these systems, and in the case of the slow speed and enrichment it goes through passages in the carb body to flow out feed holes that get exposed to vacuum with the progressive opening of the throttle plate (can get plugged), while the main system flows through the inner venturi in the throat of the carb that gets exposed to vacuum to pull fuel/air mix into the throat (very short and wider path). The idle jet sets the amount of fuel fed to the slow speed holes and draws from the float chamber, and the main fuel jet sets the high speed fuel amount mixed with the air from the air jet and perculated inside the emulsion tube before its delivered to the throat through the inner venturi. The enrichment system pumps extra fuel via a pump diaphragm that has to go through a few passages before it it squirts and is easily fouled. You should be able to inspect all these systems and spray cleaner through access ports or by removing jets/emulsion tubes and spraying down these holes to make sure they are clear. You can look down the throat(s) and operate the throttle to see if fuel squirts (engine off of course) or remove the carbs and pump the throttle to observe the spray (until the float chamber is dry). The level of the fuel in the carb (set by the float and needle and seat valve) is very important/critical to its operation and will make it run poorly if wrong as it influences how the emulsion tubes operate. The slow speed system operates up to about 2800-3200 rpms or so with overlap as it transitions to the main system. You can check each system carefully by slow acceleration to the transition point and then beyond. Read your wideband and that will give you an idea of how close your jetting is. If it backfires or snaps with sharper stabs then suspect your enrichment system. A lean condition with deceleration is not unusual, but could be an indication of a leanish slow speed system or one that's not working fully.

[srfjay]

Thanks Greg. Lots of good info. I am going to go through the carbs this weekend and clean and double check everything. I think I am getting closer.
I need to look up the info on the floats. To be able to adjust them if needed.

[srfjay]

So I wanted to double check fuel pressure . And I got a guage to help. It shows low. And this is with the rebuilt pump and I installed a electric fuel pump close to the tank. Yet still low. Maybe a clogged line?

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