Stumbling Weber

[schatzi]

Hey guys, so I'm going to put this to the forums in the hopes that I may get some fresh ideas.

I converted my friends' '82 Honda Accord hatch to a Weber 32/36 DGAV and despite my best efforts, it has not turned out like I expected.

For starters, everything is installed, what seems to be correctly, only vac lines hooked up are the brake booster, distributor, and EGR. Idle has been tuned as best I can with my engine analyzer. There are no vacuum leaks, and the air suction box (just forward of the carb) has been blocked off with a plate covering the connection to the exhaust pipe.

Problem is, The Weber stumbles. It's embarrassing. It makes it look like I don't know how to drive. Prior to the conversion the stock carb was smooth albeit slow. Now it has tons of power but just off idle in the transition zone of the butterfly it stumbles bad, cold or warm, it does it just about every time.

Any ideas? I bumped the timing up 2 degrees, it's made it a little smoother, but the stumble is still there. I'm stumped.

[2oodoor]

for starters remove the vacuum from the egr and plug off the egr itself!!!

You should have the PVC getting vacuum!

YOu may need to check your accel pump rod for binding.

[schatzi]

ok, I wasn't aware there was a PCV valve... the valve cover has it's hose connected to the underside of the air cleaner housing, so I guess I neglected to mention that.... But I didn't see an actual PCV valve during the install.

I will check the accelerator pump linkage and disable the EGR

I thought the EGR was good to leave hooked up?

[2oodoor]

no EGR has to be controlled to open at part throttle or otherwise when appropriate, never at idle
Open EGR is a direct vacuum leak underneath the EGR valve itself

[2ndGenGuy]

There is no PCV valve. Just the breather port on the valve cover... That you should just run to the air cleaner.

[mephi]

This actually seems to be a common problem with the Weber conversion. I had similar issues, and was in the process of figuring it all out when my car got wrecked. Tuning the thing in just right seemed to help, and I also advanced the distributor to the point of pinging on 87 and then started running 92 octane. Both of these things helped, but it was still there. I did notice that on the A20 intake manifold, the front mains did not kick in at the same time as the rear mains. I was in the process of figuring this out, but then the car got sandwiched between a newer accord and an X-terra. At this point I just have a Weber sitting on a bench and a parts car in the driveway.

[schatzi]

ok, EGR is disconnected, and it doesn't seem to necessitate plugging off, the valve operates still, and remains shut even with pressure applied to both ports. Only way that valve is opening is with proper venturi vacuum.

So this is endemic with the Weber. Sigh. Oh well, my Beetle stumbles like a bad dog ever since I switched to a mechanical advance disty, and I found a neat throttle modulation technique that helps her smooth out (mash the throttle every time x-D )

Now here's a better question... does anyone remember which vacuum hoses I need to hook up to get back control of the heater/ac? since the carb conversion, I have noticed that the heater controls have been rendered inert.

In the meantime I'm gonna check the vacuum diagram again, but I didn't see it on there......

[ekoms]

on my 82, directly behind carb theres a vac line running to the cabin through the firewall & has a orange/blue check valve
(http://rd.ss.yahoo.com/SIG=19defeot6...N%3DB001G7RUSQ) or atleast something similar connected. when I had a toyota carb installed on my 82 I plugged that valve on accident & the heater stopped working. hooked it back up afterwords & it worked. Im not sure about the A/C but mine also had a second vac line running through directly below the heater line. it did not have a check valve attached. my ac didn't work so I plugged it. look for 2 vac lines group running through & try/test them.

[schatzi]

thanks, yea I figured it was these two little guys, but when I was feeling around back there, I could swear to jebus that they both terminate in what feels like the wiper motor. Or some sort of big cylinder with metal arms attached.

Anyways, I'll try fiddling with those in the morning.

[2oodoor]

[QUOTE]

venturi vacuum.

So this is endemic with the Weber. Sigh. QUOTE]

No, I never had any of those issues with the three carbs I have been using the past two years.
Are you getting a good squirt from the accel pump initially? What idle jets are you using?
I did a good bit of porting on all of my apps, on the manifold as well as the adapter plates. I cant say for sure if that was proactive to bypass the stumbling or what. I do not know if those are used carbs that are acting up or not. The float level should be checked, which is about the most difficult thing about these carbs and even that is not so bad IMO.
One thing a lot of people are doing is inadvertently warping the base plate by tightening the bolts on the carb studs with the stud turning. This pushs it away from the plate below it. Be carefull not to let those bottom out on ya.

[2oodoor]

I think the float level should be a tinch higher than spec on these cars because of the position on the motor in coorilation with the effect of gravity with a FWD motor. Loose motor mounting can cause more disruption of the fuel bowl when you step on it. When some fuel is sucked out of the bowl by the accel pump then add to that the transition of fuel into the jets, there may be a fraction of a second fuel starvation occuring.
Along with rasing the level slightley though, will be a slight gas smell sometimes, life with a Weber. Even a perfect non leaking Weber will have a strong gas smell occasionally.

[85SE-i]

So this is endemic with the Weber. Sigh. Oh well, my Beetle stumbles like a bad dog ever since I switched to a mechanical advance disty, and I found a neat throttle modulation technique that helps her smooth out (mash the throttle every time x-D )

So I will bet you are using a Bosch 009 with a Solex 34PICT3 correct? The 009 and the 34PICT3 do not get along very well. My buddy Mike from Pozzi's VW in Sacramento, has a fix for this and can mod your carb to work flawlessly with the 009. I guess it is something he came up with on his own and has done hundreds of carbs, but he won't tell anybody how to do it (not even me) because he doesn't want his secret to get out. My only other recommendation is to get a Bosch 050 distributor (if you can find one as they are now discontinued). I have one on my Bug, it is mechanical advance and has a different and better advance curve so there is no stumble at all.

[A20A1]

Any news on how the cars running lately?

another thing that can effect the carb is fuel flow and pressure, as a lot of the off the line problems I initially had with these carbs were reduced by adding a regulator.

However the regs I used where cheap dial in ones and would starve the carb once I hit a certain rpm, probably due to my fuel pump not being able to keep up with the demand and overcome the restriction in the reg at the same time. I never found out for sure, but that's why I suggest to most people converting to webers to consider a better fuel pump and reg to match.