1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Calling all Weber Guru's..HELP!

Old 12-29-10, 07:17 PM
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Calling all Weber Guru's..HELP!

Let me start by saying my knowledge about this carb or any carb is very limited. I had a friend who knows about carbs set mine up (he's hard to get in contact with, which is why I turn to you geniuses). Last night I was driving home, stuck in traffic, getting irritated. When construction zone cleared, and I got onto the merger for the other expressway, I opened it up in 3rd. At about 7k RPM it hit a wall. This has never happened before, I've taken it to 8k without issues. I can't figure out what is causing it.

I checked my fuel filters (I had one pre fuel pump, and one pre FPR), seem to be ok, going to replace them tonight. All my spark plug wires are all on snug, the dizzy didn't shift (I doubt ignitor went bad because I've dealt with that issue before and that was very obvious). I get the feeling it's the carburetor. Here's why I think that...

Before when it was running ok there was a hiccup in acceleration when going from a light throttle to a medium throttle. Now when I try to go from a light throttle to a medium or high throttle, it just bogs, no power whatsoever. If I try to go anything above about 1/3 throttle it just bogs down. Fuel pump was brand new when I bought it, maybe 8 months ago, and the car has under 5k miles on it. Weber 48 DCO, 13b streetported.

In this pic, I took all 4 of the things that are under the thumb screw on top of the carb out, pulled them apart, and cleaned with carb cleaner.

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Old 12-29-10, 08:02 PM
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specs specs specs as in jetting and such. also, pull out the spark plug and tell us about it.
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Old 12-29-10, 11:01 PM
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I will give you what I can in about an hour. Here is a video of how it sounds:

http://www.youtube.com/watch?v=Q9wzkpJwf84
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Old 12-30-10, 08:34 AM
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That's odd, I can't tell exactly whether its lean or rich. It sounds lean though. Almost like it's not getting fuel. A stumble will cause that like you explained. Also, when you explain a wall? That also could be the same. Not getting fuel.

When I used to run my weber I would regularly pull the carb apart every month and clean all the jets, fuel bowl and just about everything I could get to without pulling the carb itself off; including idle mixture jets, carb inlet and inlet scrEen. I suggest doing that before going much further.(Of course clean everything with choke and carb cleaner.)

Finally, make sure the inside of your fuel bowl and carb inlet screen is extremely clean! I mean as clean as you can get it. Once I had the same problem that was do to all sorts of dirt and rust in the bottom of my fuel bowl.


Hope this helps and I wish you luck,

-crispin
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Old 12-30-10, 10:02 AM
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Here's the deal.... if the carb was running great previously then the jetting should be fine. It's highly uncommon to need to change the jets more than a step down or up for changes in season. So that likely is not your issue. You mentioned you checked your fuel filters... which is a good place to start. But since they've checked out you've got other issues. In the video you're running that carb with no air filter..... that's fine and all for guys that are drag racing and the car only runs for a 1/4 mile at a time, but if you're driving that thing on the street like that you're asking for trouble. You mentioned you were driving through a construction zone in your original post. Construction zone=lots of dust.... it doesn't take much in the way of dust and dirt to block one of your progression holes and cause an issue like this.

My recommendation would be to tear the carb down.... clean it THOROUGHLY... put it back together.. and give her a go, and for God's sake put an air cleaner on that thing!!
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Old 12-30-10, 05:29 PM
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Originally Posted by 81widemariah View Post
here's the deal.... If the carb was running great previously then the jetting should be fine. It's highly uncommon to need to change the jets more than a step down or up for changes in season. So that likely is not your issue. You mentioned you checked your fuel filters... Which is a good place to start. But since they've checked out you've got other issues. In the video you're running that carb with no air filter..... That's fine and all for guys that are drag racing and the car only runs for a 1/4 mile at a time, but if you're driving that thing on the street like that you're asking for trouble. You mentioned you were driving through a construction zone in your original post. Construction zone=lots of dust.... It doesn't take much in the way of dust and dirt to block one of your progression holes and cause an issue like this.

My recommendation would be to tear the carb down.... Clean it thoroughly... Put it back together.. And give her a go, and for god's sake put an air cleaner on that thing!!
+1
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Old 12-30-10, 06:03 PM
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I understand the air filter issue, I actually just removed it for that video. But I did drive it for a long time without one. I wish I had a A/F gauge, but I don't, I'll try to tear the carb off and clean it up. I just gotta find a PDF on that or something first, because I've never really done that
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Old 12-30-10, 06:08 PM
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Whats your fuel pressure set at, I dont see a gauge? Mine jumps all over the place and I have to set it every time I drive. Its possible it fell off and you aren't getting fuel...

Hard to go too lean with a mallory FPR though.
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Old 12-30-10, 07:41 PM
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I checked it, it's at about 3.25 psi
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Old 12-30-10, 07:42 PM
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Oh, I dont have the mallory anymore, I'm using a different FPR now, without a return line.
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Old 12-30-10, 07:55 PM
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evil everytime I go back to the wideband thread IE takes a dump on me .... once I figure it out we may be able to weld you in a bung and dial your car in (if not already installed in mine) Once mine is done I'd like to assemble some portable deal where the car just needs the buunnggg such a fun work bunnnggg

Oh and wack that dayum weber with a mallet



LMAO j/k
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Old 12-30-10, 08:09 PM
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you need to go one size bigger on your idle jet so it wont bog and did you check the spark plugs?
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Old 12-30-10, 08:14 PM
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Sorry not yet, I had to get my other car back online. I'll try to get some photos and info in the next few days.
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Old 12-30-10, 08:26 PM
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where do you live in Vegas? I'm up there at least once a month. My in-laws and cousins live near Rainbow and Blue Diamond
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Old 12-30-10, 08:48 PM
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LMAO you guys pass each other at the 7-11
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Old 12-30-10, 08:58 PM
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haha I live about a mile from Blue Diamond on Rainbow
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Old 12-30-10, 09:26 PM
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Have you see a sunburnt light blue 85 GSL with tinted windows, all stock, that was my old FB. PUt it back to stock, passed it down to my son as his first car and then to my godson as his first car.
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Old 01-01-11, 06:21 PM
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No, I don't really see any FB's in this area. Seen a few FD's though.
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Old 01-03-11, 07:42 PM
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Ok, well heres an update. A few days ago I was in my garage pulling out the FB to work on the wife's Altima, and noticed this on the ground:



Looked pretty damn familiar to me, so I took off the intake and carb and found it's home:



So I put that back in, and had a rebuild kit handy so I rebuilt the carb as well, and everything runs as it was prior to this event. I'll still be posting the info for all the jets and stuff I'm running, likely tomorrow when the sun comes back out. It's time to tune this sucker!
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Old 01-04-11, 10:09 AM
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Hmmmmmm... it's almost like I've done this before...
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Old 01-06-11, 04:01 PM
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Ok I finally got outside and got some specs. If anyone has suggestions let me know cuz I'm sure this stuff may raise an eyebrow. 85GS, Pineapple large Streetport (template, they did not build), RB header with 2.5" exhaust:

Main Jets - 190
Idle Jets - 60F10
Air Corrector - 140
E-Tube - F11
Pump Jet - 45
Chokes - ??
Aux Venturi - ??
Needle/Seat - 250
Fuel Pressure @ 3.5 psi

Am I able to see the Chokes and Aux Venturi without pulling off my carb? It's a 48DCO
http://www.racetep.com/weber/48DCOSP.pdf
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Old 01-08-11, 03:07 PM
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Bump for suggestions
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Old 01-08-11, 04:10 PM
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Originally Posted by EvilWankel View Post
Bump for suggestions
you may be able to see the venturi number looking into the carb, its cast into the top on the inside.

the aux venturi needs to be removed, but really as long as they match we're ok.

jetting is hard to say, as it depends on things like fuel pressure, and how much air the engine/exhaust flows. for instance i'm running the same idle jet on my P port and its fine, but i'm running more fuel pressure, and the main circuit is doing most of the work by 2000rpms

it also depends on what you're trying to fix.

i'd say the E11 E tube, is too lean/small. there is an E tube chart and it references E tube to engine size.
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