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> Carb guru's I need your help, Break out the black magic book I'm stumped
Joe Ricard
post Jun 28 2006, 05:20 AM
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Car has been progressively getting worse.
the problem is off idle stumble. I have to date pulled carbs cleaned out everything.
Rechecked and slightly adjusted floats 10mm.
Tweaked on accelerator pump linkage (no change).
Went down idle jet made it worse 53 to 50.
Went up to 55 idle now it sort of covers up the problem but still stumbles.
Checked timing Mallory dizzy. bumped it up about a degree (slightly bettter) but still stumbles.

2.0L 86b cam Tangerine 40 IDF's 32mm vents.

Runs like a scaulded dog on main jets.

Also spent 1/2 hour synching up carb linkage (perfect) off idle. still stumbles.

So I am out of tricks. What am I missing. (IMG:style_emoticons/default/blink.gif)
Oh yea valves are set good too. good plug wires good plugs.
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J P Stein
post Jun 28 2006, 05:35 AM
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You gots MSD?
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Joe Ricard
post Jun 28 2006, 05:43 AM
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QUOTE(J P Stein @ Jun 28 2006, 06:35 AM) *

You gots MSD?


Had a Mallory Hyfire but that took a shit 6 months ago. Running the Mallory Dizzy with Mallory Pro E coil and inline Resistor.

Hmmm Might just put a Bosch Blue coil on it and see what it does. Good call. (IMG:style_emoticons/default/beer.gif)
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1bad914
post Jun 28 2006, 06:03 AM
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Do you have a hole in your butterfly? Sometimes that hole needs to be blocked. I had a 69 Bus that required that hole to be blocked, it drove me crazy. I'll dig up a reference on it.
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Joe Ricard
post Jun 28 2006, 06:31 AM
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No hole in Throttle plates.
However The symptoms lead toward clogging progression ports.
Got half a mind to do whole sale swap on the carbs. If it is still stumbling then there could be sumpin wrong internally to the engine.
Hmm imagine that. probably 60,000 miles on this engine and ain't none of them easy.
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SGB
post Jun 28 2006, 07:06 AM
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Didja check the air bypass system? How many turns out from the bottom are those air-bypass needle screws? My webers need almost 3 full turns out from the bottom or I get loading up (too rich) coming off idle. Do you get a puff (or more) of black smoke when you throttle up? I generally get better response with a slightly rich mixture, but I think gas was condensing on the insides of the manifold if I let it idle for very long without adding more air with those by-pass screws. Another possibility is that the accel pump is dribbling fuel into on of the carbs. Make sure the lever arm and actuating cam are free to move easily. On the lever arm there is a little metal wheel that follows the ramp to make the accel pump go and on mine, the wheel was gumed up on its axle thing and wouldn't clear all the way off the cam ramp. Good luck!
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Joe Ricard
post Jun 28 2006, 09:22 AM
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Yea, I have the air by-pass screws closed as advised by many a carb junkie here.
Carbs are new style with spring loaded reach rod. no cam wheel.
no visible dribbling from nozzles

going leaner on jets made it worse so I went the other way Bigger. 55 idle jet now.


Could it be new gas blends are raising hell here? no idea what's in the rat piss down here but they sure are proud of it.
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redshift
post Jun 28 2006, 09:25 AM
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heh I know the feeling.

My car runs different on EVERY fill up.


M
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914fan
post Jun 28 2006, 09:28 AM
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could be a intake leak. A small one at that. especially since going to a larger jet helped.
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andys
post Jun 28 2006, 09:41 AM
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You might also be lean on your idle mixture strength. Richen it up and see if it goes away.

Andys
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Joe Ricard
post Jun 28 2006, 09:57 AM
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QUOTE(914fan @ Jun 28 2006, 10:28 AM) *

could be a intake leak. A small one at that. especially since going to a larger jet helped.

Hmm, time to stop by NAPA for some gasket material. I think you are on to something.

Hell I'm >< close to pulling the engine for a tear down.
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HarveyH
post Jun 28 2006, 10:04 AM
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When I got my car (pre internet), the PO had put in the cam and Weber 40"s. I did points, plugs... (IMG:style_emoticons/default/smash.gif) ...etc, but it still ran a bit rough, coughing, bogging, misfire ... I called several of the Weber distributors to get recommendations on where to start. Every one recommended that I start by installing a multi-spark CD box to the ignition. I started with just a Pertronix (yeah, I know, but I've been running it for 10 years), which helped a bit. About a month and a half later I put in a Crane HI-6, PS-91 coil, and opened the plugs to 0.045". MAJOR improvement. (IMG:style_emoticons/default/driving.gif) Still had to play around with jet sizes a bit, but the ignition upgrade was the biggest factor
HTH
Harvey
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Joe Ricard
post Jun 28 2006, 10:29 AM
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Aaron.. What gap are you running on your plugs with the Mallory Pro E coil? 50,000 volts should not have a problem jumping .045 gap. Right?
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Aaron Cox
post Jun 28 2006, 10:56 AM
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QUOTE(Joe Ricard @ Jun 28 2006, 09:29 AM) *

Aaron.. What gap are you running on your plugs with the Mallory Pro E coil? 50,000 volts should not have a problem jumping .045 gap. Right?


hey joe...

i get a lean stumble on transition still... so i am in the same boat ....

i have .050 iirc with the hyfire and big coil... ALSO running cooler NGK b7es plugs

clears the plugs nicely (IMG:style_emoticons/default/smile.gif)

12/28 timing...

whats your initial advance?
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SGB
post Jun 28 2006, 01:14 PM
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Try adding a little air Joe. The CBs weber bible says "3 to 4 turns out". Worked for me.
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Dr. Roger
post Jun 28 2006, 02:09 PM
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I'd replace the accelerator pump diaphragms. at 5 bucks a pop it's a cheap fix if that's the problem.

yes, sometimes i'm a parts swapper. =-)

good luck.
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J P Stein
post Jun 28 2006, 02:26 PM
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I've had lean stumble but have banished it from my engine room.
.....this is on 3 hole Webers but....air & fuel are the same on a 4 pooper.

In a phrase....ya gotta run rich, ya sumofabitch.
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Joe Ricard
post Jun 28 2006, 02:37 PM
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QUOTE(J P Stein @ Jun 28 2006, 03:26 PM) *

I've had lean stumble but have banished it from my engine room.
.....this is on 3 hole Webers but....air & fuel are the same on a 4 pooper.

In a phrase....ya gotta run rich, ya sumofabitch.



I'm not buying that crap. The car used to freaking light the hoosiers up right off of idle. Now I can't spin skinny little crappy streets unless I dump the clutch at 3,000 RPM. This is going to require some bigger investigation. I got my path set in front of me. Now I just need to follow it and find the cause.
Plugged and idle jet going to lunch so this all just may be a wad of sumpin left over from a gremlin party.

Accel jets squirt good and consistantly.
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Kargeek
post Jun 28 2006, 02:49 PM
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Joe,

The foundation for any carb adjustments is proper engine timing. Usually carb's don't go out of adjustment unless it's dirt or mechanical issues. In order:

Check engine timing?
Fuel pressure?
Carbs sync?
Idle mixture?



Dave H
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Joe Ricard
post Jun 28 2006, 03:03 PM
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Thanks Dave,
I get the Idea .... Back to basics. which means go through all the stuff I thought I did right last night in the dark driveway with a flash light.
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