New Weber owner!!! I think I broke something...

[LewZor]

Hello All! Put the K646-38 on my 1985 KC ST Auto today and thought I hooked everything up right. Now it idles awesome but when I take it for a spin it drives nice until I put the hammer down and forget going over 45 mph. It starts chugging pretty bad. Revs great when in Park and Neutral but in Drive it will go smooth until I give it more gas. Any ideas would be great.

I set the timing and have the vacuum advance hooked up.

[Lockleaf]

Did you tune it? Are the jets correct for a z24?

[LewZor]

I just put it on the truck straight out of the box.from Redline. I didn't know that it would have to be tuned.

[datzenmike]

It's a 38/38 Outlaw??? That's a synchronous carb which means both barrels open together. It's also for a large V6 or small V8 displacement and when used on a small 2.4 tends to bog badly. Most small engine carbs have a vacuum secondary so that it starts out on one barrel and only adds more as needed. The weber 32/36 is a progressive carb.... it uses one barrel until the throttle is 1/2 to 3/4 open then manually opens the secondary. This gives better low and mid range driveability.

 

You are going to have to learn how to drive this carb as it's too big. Too big to step into it right away from a stop or at lower speeds. Try half throttle until the engine revs up and can actually use the second barrel. When it 'chugs' let up on the throttle until the engine starts pulling strong and gradually add more throttle as it will take it. You'll have to just get used to not giving full throttle below a certain RPM.  

[Charlie69]

The Weber 38 works great on a Z24.  It will not get good gas mileage though.

[LewZor]

Oh shoot! So the chugchugchugchug thing that is happening is it's way of telling me to take my time getting up to speed? Maybe I should just swap it with the 32/36 version. My daughter will be the main driver of the truck. I just did the Tim The Toolman Taylor thing and wanted More Power. Would a fuel regulator work to help the situation? Thank you guys so much for the help. I like doing this stuff by myself as much as I can. Lew

[datzenmike]

A 38 will give you some more power but it has to rev up first. I doubt your daughter will have a heavy foot but in an emergency she might floor it too fast.

[datsunaholic]

The 38 isn't so big that it would make the engine fall on its face over 45MPH, though.  I've had one on my L20B for years, a used one of unknown history or jetting and it runs fine.  Sure, jabbing the throttle sometimes causes bog (at anything under 40MPH, that is) but hammering it over 50 the truck launches like a cat shot.  Killed my Dogleg transmission.

 

What you have sounds like it's running out of fuel, as if the float is too high or you have a restriction causing slow fuel delivery. Or you have the bypass hooked up weird (no reducing orifice). 

[Lockleaf]

Get some pics posted up of your install. They will help with a couple things at least.

[Charlie69]

If your daughter will be driving it go to a 32/36 DGEV Weber.  Better mileage and still has better power than the stock carb.  Webers are altitude sensitive.

[tr8er]

What Mike said is dead on. So is Charlie. For your daughter, get her the progressive. The 38/38 takes getting used to. I've done so and I don't think it was worth it. Way way way better with a manual transmission. I hope you have that. If you can keep it at higher revs, it has a lot to deliver. It starts to push itself at a certain point seemingly. But off the line, you need gearing low, and right leg slow.

 

L20B in a 510. Auto to stick

[banzai510(hainz)]

should work better the faster you go.

something is wrong

 

 

I put a 38/38 on my L16 with cammed L20 head. above idle it worked fine(still over jetted but worked )

 

FOR A GIRL AND LOTS OF HILLS USING A CLUTCH IS NOT GOOD

maybe the choke flap is still chosed. You hook up the electric wire to the carb?????????

[Rhino13]

My 32/36 is doing this exact same thing right now and I'm thinking it's a clogged jet in the secondary. I know a few people with 38s on their 720's and love them, if anything just put smaller jets in it and see if that helps. Or better yet just tear it down and check it out, maybe you got some crud in there from your gas tank. Did you replace the fuel filter with the new carb?

[LewZor]

I installed it right out of the box. Should I "tear it down" and blow out all the jets? The chugging makes me think that it's not getting enough gas, but it's all of a sudden. Oh, it's an Automatic. Before I decided to ditch the original I replaced the fuel filter and the fuel pump (pump says works between 2-4 1/2 psi).I did all the plugs and wires and coils too. When I set the timing I found that I cannot turn the distributor any further counter clockwise to move the timing mark past maybe 2-3 btdc. Can the distributor be off a couple "teeth?" Anyway, I put everything on according to the instructions except for the fuel regulator. I will get some pics of the install as soon as I can. Again, thanks everyone!

[Rhino13]

My fuel pump goes to 8 psi, it's a facet pump.

[banzai510(hainz)]

is this a 2 spak plug per cylinder head?

You changed the wires and put then on . Put the after on the before spot??????????

 

if stock pump then your fine.

 

why you change this anyways maybe you had plugged fuel filter(that's a hail mary on my part and highly dought that's it anyways. something changed.

 

was this running before OK? if so then why dist be off a tooth???????

I believe you adjust the timming with a auto with it in gear But Datzenmike would know for sure.

[poopypants720]

I installed it right out of the box. Should I "tear it down" and blow out all the jets? The chugging makes me think that it's not getting enough gas, but it's all of a sudden. Oh, it's an Automatic. Before I decided to ditch the original I replaced the fuel filter and the fuel pump (pump says works between 2-4 1/2 psi).I did all the plugs and wires and coils too. When I set the timing I found that I cannot turn the distributor any further counter clockwise to move the timing mark past maybe 2-3 btdc. Can the distributor be off a couple "teeth?" Anyway, I put everything on according to the instructions except for the fuel regulator. I will get some pics of the install as soon as I can. Again, thanks everyone!

doesn't sound like WOT bog, sounds like your starving for fuel under a load. Check the float, maybe your needle valve needs to be smaller, maybe you had crud in the bowl from the factory and didn't know it n sucked it into the jets(considering you have new filters)...

 

I'd tear it down, check jets, emulsion tubes and blow out passageways, put it back together, tune it for best lean idle(instruction came with the weber on how to do it), and you should be good to go.

 

As for the timing. Sounds like your ONE tooth off. Not even a couple teeth. And getting that fixed should help since most webers like more advance. I run mine@ 10-15° btdc tuning to sound... It makes a huge difference through all the gears and once mechanical/vacuum advance takes over.

 

Just the same... After all this, if it's not tuned just right, you still might get a hesitation/bog with the 38 and that usually requires then playing with air correction jets and emulsion tubes and CAN be overcome... But otherwise will take learned throttle control and might be better off with the 32/36 for your daughter.

 

This guy has some good tuning videos and their website and racetep.com both have great into on Weber tuning

 

https://youtu.be/A44-xG3pKlY

 

https://youtu.be/fhYSo6u-Jm0

 

https://youtu.be/BfIH26O2Ijg

[Charlie69]

What was wrong with the stock carb? 

 

I cannot say about the quality of any Webers that do not come from Pierce Manifolds.  Been doing business with them for over 3 decades.

 

What pump did you replace the original with?

 

How did you plumb the Weber?  Pictures of the installed Weber would help.

[LewZor]

Here are some pics?

 

 

[LewZor]

So here is an update. Put in a new battery. measured the fuel pressure at the carb (1.75 psi) and at the fuel pump (3 psi). From pump to carb there is no filter as there is a filter before the pump. Could there be a blockage or something lowering the psi from the pump to the carb? Pump says 2.5-4 psi. Should I get a bigger one and then lower the pressure with a regulator? Or run a new line directly from pump to the carb?

[datzenmike]

You might have the return and the pump line reversed under the intake. Between the carb and the valve cover is a Y shaped pipe. The top pipe is fuel to the carb. Of the two pipes pointing downward, one goes to the fuel pump and one goes to the return to the tank. The return to the tank has a restriction in it so must NOT be connected to pressure or pump side. 

 

The fuel return line is to the front and the pump line is to the rear. Of the two metal lines back to the rear of the truck... the return line is always the larger diameter.

[Charlie69]

Your pump is not pushing enough pressure and is probably not designed to run continuous.  There is a fuel return line one the Z24 that has a small orifice to allow pressure to build at the carb.

 

First the opposite side of the fuel line connection on a Weber 38/38 is a brass plug.  Pull the brass plug there is a spring and a filter in there.  Check for crap from the install.

 

Second do not pull the Weber apart as this will void any warranty.

 

This looks like it could be kinked.

 

 

If you pull the fuel line off off the pipe you can take a phillips screw driver just small enough to fit in the pipe and tweak it forward enough to use a short piece of fuel hose to connect to carb.

 

The fuel pump you want to buy is the Facet. ask Rhino!

 

Here is a link:

 

http://www.ebay.com/itm/FACET-PUROLATOR-PRO-87SV-FEP-87SV-FUEL-PUMP-TRACTOR-GENERATOR-ONAN-/182022758004?hash=item2a6166de74:m:mMG-tFrnaCrgJuzHgdr4AIw&vxp=mtr

 

Also check your paper oh the Weber and if you did indeed order a 32/36 then you need to call Redline and tell them about the mistake.  They should send you the correct carb and take the 38 back.

[tr8er]

1.75 is low. Flow rate and pressure I believe are different values, but that could certainly be an issue you are seeing. Run it at higher rpms in your garage and see if starts struggling. If so, squirt a bit of gas in the Venturi to make sure it helps. Assuming it does, bypass your fuel line between the pump and the carb. triple check your hose clamps. No leaks

 

Edit: definitely check your return line isn't switched with supply.

[LewZor]

Hey! Quick update...Installed the OLD Fuel pump and got 4psi instead of 3 at the pump and about 2.75psi instead of 1.75 at the carb. Took it out for a drive and it seemed to be running great and then the "chugchug" started and it got to the point that I had to put it in neutral, rev it up, put it in gear and chug it back home. All in about 2 miles around the block twice.