Too rich or too lean? What does this spark plug tell you?

[tr8er]

Through the needle hole as you described. I think the vacuum would still draw in fuel, still run. Check the needle and port, put it in, and it should stall. If not, no idea. If it does stall, good. Now adjust the needles and the idle jet and the choke. Gooder?

[datzenmike]

I checked all the possible connections and also took the 1 way valve that goes to the break booster and checked it. Replaced the PCV valve. Is it possible the carb is faulty? I mean if the butterflies are closed is there another route air could flow? 

 

Even with the 'butterflies' closed some air leaks in, not much though.

[Profile]

On a Holley/Weber 5200 32/36 there is a power valve in the bottom of the float bowl. If it leaks it will run rich. Don't know if the Weber 32/36 is the same.

[Letsurf]

Took the truck to a local carburetor guy. All he does is rebuild carbs (for 35 years now). He looked it over and took it for a spin and said that there wasn't anything wrong except that the carb is too big for the engine. He said that he could solve the issue of it stalling upon acceleration by drilling out the accelerator pumps so it would get more fuel. I'm thinking the large plenum and large carb is creating a low velocity situation when I first open the throttle and that is where the problem lies. Sounds like I need to go back to the 32/36 or add a header and cam.  :rolleyes:

[toylet]

I have a LZ22 in my 510 with the Weber 38/38. I had to install a wide band o2 sensor to get the mixture right. Basically all the jets were too rich from the factory so I had to replace them, plus it would diesel when shutting off engine. installed the optional fuel idle cut off valve. Dieseling has gone away PLUS it starts a lot easier now because the fuel is not flooding the cylinders on shut down anymore making it leaner on startup. Going from the 32/36 to 38/38 was a very noticeable change.

[Letsurf]

I have a LZ22 in my 510 with the Weber 38/38. I had to install a wide band o2 sensor to get the mixture right. Basically all the jets were too rich from the factory so I had to replace them, plus it would diesel when shutting off engine. installed the optional fuel idle cut off valve. Dieseling has gone away PLUS it starts a lot easier now because the fuel is not flooding the cylinders on shut down anymore making it leaner on startup. Going from the 32/36 to 38/38 was a very noticeable change.

 

What do you mean when you say noticeable change? 

[datzenmike]

The intakes are almost identical. Carb is a bit large for a 2.4 is all. A 'larger' cam will only make it worse at low speeds.

 

The 38/38 is a synchronous carb EVERYTHING opens when you floor it. Plenum vacuum drops almost to nothing with two 38mm holes suddenly opening up. The engine does not have enough displacement pulling air through the carb, so gas can't be sucked in and it 'falls on it's face'. You will have to drive away from a stop and add throttle as the engine revs up.

[Letsurf]

The intakes are almost identical. Carb is a bit large for a 2.4 is all. A 'larger' cam will only make it worse at low speeds.

 

The 38/38 is a synchronous carb EVERYTHING opens when you floor it. Plenum vacuum drops almost to nothing with two 38mm holes suddenly opening up. The engine does not have enough displacement pulling air through the carb, so gas can't be sucked in and it 'falls on it's face'. You will have to drive away from a stop and add throttle as the engine revs up.

 

I have a header for it but would just need to have a new tailpipe run. Would the header solve the issue with it stalling? I'm getting ready to send this 38 back to weber and they said they will accept the return but are absolutely certain that the 38 is the best for the z24i intake. I'm so confused... 

[Lockleaf]

Header won't change much, if anything. The head is the biggest flow restriction on the z24. The exhaust flows pretty well for the stock head. Any benefit would be seen at the higher rpms.

 

What does Weber say about the carb z24 as compared to the z24i?

[datzenmike]

Depends what you want. The 38/38 would be the best for all out performance but as stated, will be more problematic driving around in non performance situations. You have to work at driving it. The 32/36 would be a better all round carburetor with more performance than the stock carb.  The stock carb would be the best carb for all round driving, idling, emissions, gas mileage... but the least performance.

 

The Z24 exhaust has more than enough flow for the engine. A header won't do anything for it. Use the money saved for a low restriction 'muffler'.

[Letsurf]

Header won't change much, if anything. The head is the biggest flow restriction on the z24. The exhaust flows pretty well for the stock head. Any benefit would be seen at the higher rpms.

 

What does Weber say about the carb z24 as compared to the z24i?

 

They are saying that the 38 would be better for the large plenum that the z24i has. But my problems didn't start until I switched from the 32/36 to the 38 so either I have a bad carb or they are wrong. I tried every jetting configuration feasibly possible and it still has issues when doing rolling stops and then taking off.

[datzenmike]

I told you... you have to give it 1/4 or 1/3 throttle and let it build up some speed before mashing it to the floor. The engine displacement is too small for that carb and isn't drawing enough air through it at low speeds. You are going to have to learn what works best for it. Too much throttle at low speeds and it will bog.

 

Time to put the 32/36 on I think.

[distributorguy]

Most carb problems are actually weak ignition.  Try a distributor tune-up and advance your timing a few degrees.  That 38/38 is not too big - it just needs a bunch more initial timing to run properly, like being set at 20 degrees BTDC!  That will get rid of the dead spot, but cause other issues at higher revs, so a distributor recurve is in order.  

[datzenmike]

Factory timing is 3 degrees. The Z24 has dual plugs, both are the EI system so I doubt the ignition is weak. Learning to drive this carb or swapping to the smaller one is easier.

[az_rat210]

Switch to the 32/36 like Mike says.  Then and this is very important.....read up on tuning the weber.  Read any articles you can find.

 

Redline Recommendations.

 

http://www.redlineweber.com/html/Tech/carburetor_set_up_and_lean_best_.htm

 

Ben Pender's Weber Tuning Guide (really good)

http://www.justbrits.com/Articles/TuneWeber.html

 

Key point on the idle, the idle speed screw should not have to be more than 1 full turn in.  Past 1 full turn opens up the transition holes/ports causing a rough idle.

 

You will need some additional jets to do the tuning most likely.  Redline has tuning kits that you borrow and return, then are only charged for the jets used (I think).