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  #1  
Old 11-17-2019, 01:26 AM
The Young Timer
 
Join Date: Mar 2019
Location: Schaumburg Illinois
Posts: 78
Steps of tuning carbs vs timing

I really need some help tuning my mbz 220sb. Finally got it to run with some fresh spark plugs, the “new” plugs that were on it after 2 uears were all shorted to each other, essentially the inside of the spark plug was no good on ALL of them which resulted in intermitent good spark, weak spark and ultimately most of the time no spark. After eeplacing the plugs i started her up and she ran great until she “ran out of gas.” The thing is there is fuel in the tank and pump supplies adequate pressure considering i converted to electric and so i just need to find out which to tune first, timing? Or carbs? And when i tune the carbs how do i do it? I have an air meter for them but i have no idea if my mixture is stoich or not

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  #2  
Old 11-17-2019, 11:06 AM
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Location: Los Angeles (Altadena)
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First of all, what car/engine do you have, and what types of carbs?

Second, are you sure the fuel is making it to the carbs? There can be a lot of reasons why it might not (speaking as someone who just had a cracked hose resulting in an air leak so the fuel pump was sucking in air instead of pumping in gas). Take of the fuel supply line at the carb, put it in a jar or something to catch fuel, and verify that when the car is in the "on" position gas comes shooting out of it.

Third, take the tops off the carbs and see if there is fuel in the float bowls. (only do this if you verified that fuel is coming from the supply line).
Then report back.

Finally, did this all start to happen after you replaced the fuel pump with an electric pump?

I can't think of a reason that tuning or timing would either one be the problem here.
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  #3  
Old 11-17-2019, 02:43 PM
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Adjust point gap first, then ignition timing, adjust the valves and then the carbs. The carbs are done on a warm engine. Before adjusting carbs rev the engine and push the choke plates closed intermittently to help clear passages, look at the top of the carbs for air bleeds, put on goggles and spray carburetor cleaner through them.

Good luck!!!
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Last edited by Sugar Bear; 11-17-2019 at 03:01 PM.
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  #4  
Old 11-17-2019, 05:46 PM
The Young Timer
 
Join Date: Mar 2019
Location: Schaumburg Illinois
Posts: 78
Quote:
Originally Posted by ScooterABC View Post
First of all, what car/engine do you have, and what types of carbs?

Second, are you sure the fuel is making it to the carbs? There can be a lot of reasons why it might not (speaking as someone who just had a cracked hose resulting in an air leak so the fuel pump was sucking in air instead of pumping in gas). Take of the fuel supply line at the carb, put it in a jar or something to catch fuel, and verify that when the car is in the "on" position gas comes shooting out of it.

Third, take the tops off the carbs and see if there is fuel in the float bowls. (only do this if you verified that fuel is coming from the supply line).
Then report back.

Finally, did this all start to happen after you replaced the fuel pump with an electric pump?

I can't think of a reason that tuning or timing would either one be the problem here.
Its an M180.940-10-051009 with dual solex 32/34 paita setup and im not positive considering the old vacuum pump never got a chance since i just replaced it immediately with electric. Plus i say which one first timing or carbs since im not sure where to start
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  #5  
Old 11-17-2019, 05:49 PM
The Young Timer
 
Join Date: Mar 2019
Location: Schaumburg Illinois
Posts: 78
Quote:
Originally Posted by Sugar Bear View Post
Adjust point gap first, then ignition timing, adjust the valves and then the carbs. The carbs are done on a warm engine. Before adjusting carbs rev the engine and push the choke plates closed intermittently to help clear passages, look at the top of the carbs for air bleeds, put on goggles and spray carburetor cleaner through them.

Good luck!!!
Gap was adjusted correctly, but ill recheck when i get a chance considering its getting colder by the day and the sun is going away at like 4:30 now. I did valve adjust right after i replaced the cyl head which was about like 6 months ago. So carbs dont touch until warm, what if the car keeps dying because its too lean or something? What this air bleeds?
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  #6  
Old 11-17-2019, 06:13 PM
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Valves should be adjusted once soon after a valve job/grind as they seat themselves.

Yes adjust carb mixtures warm.

Air bleeds, small orifices 1/32" approx. in the top plate of the carb, can be seen with air cleaner off looking at top of carb.

Good luck!!!
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  #7  
Old 11-17-2019, 09:18 PM
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Location: Los Angeles (Altadena)
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Quote:
Originally Posted by Wolfbane323 View Post
Its an M180.940-10-051009 with dual solex 32/34 paita setup and im not positive considering the old vacuum pump never got a chance since i just replaced it immediately with electric. Plus i say which one first timing or carbs since im not sure where to start
I'm assuming you mean the old fuel pump, not the old vacuum pump. I'm still going with "make sure there is gas in the carbs" before you start messing with timing and valves and tuning. It ran for a few minutes just fine. And then it stopped. Why? Usually it means a lack of fuel.
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  #8  
Old 11-20-2019, 06:15 PM
The Young Timer
 
Join Date: Mar 2019
Location: Schaumburg Illinois
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Quote:
Originally Posted by Sugar Bear View Post
Valves should be adjusted once soon after a valve job/grind as they seat themselves.

Yes adjust carb mixtures warm.

Air bleeds, small orifices 1/32" approx. in the top plate of the carb, can be seen with air cleaner off looking at top of carb.

Good luck!!!
Is the air bleed under the triangle lookin thing from the tops of the carbs? Id post a pic but not sure how to, because thats the only thing i see on the tops that could be for bleeding air but isnt it a diaphram?
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  #9  
Old 11-20-2019, 06:21 PM
The Young Timer
 
Join Date: Mar 2019
Location: Schaumburg Illinois
Posts: 78
Quote:
Originally Posted by ScooterABC View Post
I'm assuming you mean the old fuel pump, not the old vacuum pump. I'm still going with "make sure there is gas in the carbs" before you start messing with timing and valves and tuning. It ran for a few minutes just fine. And then it stopped. Why? Usually it means a lack of fuel.
I mean it dies but i can get it to start again but like it just dies, if it helps i have one of this electric universal low pressure fuel pumps from autozone

https://www.autozone.com/external-engine/fuel-pump/spectra-premium-gasoline-diesel-fuel-pump-e8016s/191528_0_5752

Will a vacuum oem fuel pump work better than this?
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  #10  
Old 11-20-2019, 07:14 PM
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Location: Los Angeles (Altadena)
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Quote:
Originally Posted by Wolfbane323 View Post
I mean it dies but i can get it to start again but like it just dies, if it helps i have one of this electric universal low pressure fuel pumps from autozone

https://www.autozone.com/external-engine/fuel-pump/spectra-premium-gasoline-diesel-fuel-pump-e8016s/191528_0_5752

Will a vacuum oem fuel pump work better than this?
I can't speak to whether or not an OEM pump would be better than the electric pump you have installed.

If I understand you correctly, it will start on its own repeatedly and die fairly quickly. That means that there is gas in the carbs, but the floats could be set wrong.

What is the history of this car in terms of running, has it sat for a long time? With gas in it? If so the carbs are going to be gummed up.
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  #11  
Old 11-20-2019, 07:28 PM
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Join Date: Feb 2011
Location: Modesto CA
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Quote:
Originally Posted by ScooterABC View Post
Take off the fuel supply line at the carb, put it in a jar or something to catch fuel, and verify that when the car (key switch) is in the "on" position gas comes shooting out of it.

Third, take the tops off the carbs and see if there is fuel in the float bowls. (only do this if you verified that fuel is coming from the supply line).
Then report back.

Finally, did this all start to happen after you replaced the fuel pump with an electric pump?

I can't think of a reason that tuning or timing would either one be the problem here.
Quote:
Originally Posted by Wolfbane323 View Post
I mean it dies but i can get it to start again but like it just dies, if it helps i have one of this electric universal low pressure fuel pumps from autozone

https://www.autozone.com/external-engine/fuel-pump/spectra-premium-gasoline-diesel-fuel-pump-e8016s/191528_0_5752

Will a vacuum oem fuel pump work better than this?

Wb:

1) The fuel pump specs indicate a pump that is more than sufficient.
2) Go thru the flow check as outlined by Scooter.

There may be a problem with the float valves, the float levels, or clogging of the jets.
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  #12  
Old 11-20-2019, 07:44 PM
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Also, it never hurts to look down the throat of the carb with a flash light while pumping the gas. (unless it happens be running and it backfires). That will quickly answer the question "is there gas" ?

Those little bores that were being discussed is a zenth thing. You've got the older, oval carbs IIRC (or maybe they're the even older, round ones?) Even with a low pressure electric pump, there should be a means of returning excess fuel to the gas tank. It's also another place to look to see that you have fuel flowing in the general area. I used to keep a spare gas filter in-line there just to be able to see the fuel flow.

And like the others said, once you know you have gas, ensure the ignition is to spec. Idle at starter speed is easy enough to ensure. Yet another "why doesn't it run?" test is to give it a shot of ether. If that gets it running for 2 seconds, then you're looking for a fuel delivery issue. If that doesn't, you might want to check the plugs to see if they've been fouled up with unburned fuel. A little wire brush should help with that.

BTW, a whole motor for your car is for sale on craigs list not too far from me here on Long Island for 350$. No clue regarding it's condition. There was alos one up by Fredonia along lake Erie in the summer, I am sure that one is gone to scrap by now.

-CTH
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  #13  
Old 11-20-2019, 07:48 PM
The Young Timer
 
Join Date: Mar 2019
Location: Schaumburg Illinois
Posts: 78
Quote:
Originally Posted by ScooterABC View Post
I can't speak to whether or not an OEM pump would be better than the electric pump you have installed.

If I understand you correctly, it will start on its own repeatedly and die fairly quickly. That means that there is gas in the carbs, but the floats could be set wrong.

What is the history of this car in terms of running, has it sat for a long time? With gas in it? If so the carbs are going to be gummed up.
Yes it sat for a hella long period of 37 years! First things first i cleaned the fuel tank and rebuilt the carbs but i messed up so i got a pair of donor carbs and rebuilt the donor carbs CORRECTLY this time. But ever since then it does sit for long periods since i dont drive it as much since i am not scared to say i am terrified of taking this car on the mainroad afraid of leaving me stranded. But if the car sits for smaller periods like 6 weeks do i need to clean the carbs every time? And the rebuild kits had new needle valves for the tops of the carbs and i put those on
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  #14  
Old 11-20-2019, 07:50 PM
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Location: Los Angeles (Altadena)
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Quote:
Originally Posted by Wolfbane323 View Post
Yes it sat for a hella long period of 37 years! First things first i cleaned the fuel tank and rebuilt the carbs but i messed up so i got a pair of donor carbs and rebuilt the donor carbs CORRECTLY this time. But ever since then it does sit for long periods since i dont drive it as much since i am not scared to say i am terrified of taking this car on the mainroad afraid of leaving me stranded. But if the car sits for smaller periods like 6 weeks do i need to clean the carbs every time? And the rebuild kits had new needle valves for the tops of the carbs and i put those on
Are you saying that after you rebuilt the carbs you could drive the car around? And that you leave it parked for 6 weeks at a time? And that now it doesn't want to run? My first guess would be dirty idle jets. (if the above are all true). When it was running was it running well? The other thing to do is go through the linkage adjustment process as defined in the Big Blue Book (Maintenance, tuning, unit replacement blah blah blah).
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  #15  
Old 11-20-2019, 07:52 PM
The Young Timer
 
Join Date: Mar 2019
Location: Schaumburg Illinois
Posts: 78
Quote:
Originally Posted by cth350 View Post
Also, it never hurts to look down the throat of the carb with a flash light while pumping the gas. (unless it happens be running and it backfires). That will quickly answer the question "is there gas" ?

Those little bores that were being discussed is a zenth thing. You've got the older, oval carbs IIRC (or maybe they're the even older, round ones?) Even with a low pressure electric pump, there should be a means of returning excess fuel to the gas tank. It's also another place to look to see that you have fuel flowing in the general area. I used to keep a spare gas filter in-line there just to be able to see the fuel flow.

And like the others said, once you know you have gas, ensure the ignition is to spec. Idle at starter speed is easy enough to ensure. Yet another "why doesn't it run?" test is to give it a shot of ether. If that gets it running for 2 seconds, then you're looking for a fuel delivery issue. If that doesn't, you might want to check the plugs to see if they've been fouled up with unburned fuel. A little wire brush should help with that.

BTW, a whole motor for your car is for sale on craigs list not too far from me here on Long Island for 350$. No clue regarding it's condition. There was alos one up by Fredonia along lake Erie in the summer, I am sure that one is gone to scrap by now.

-CTH
Ah ok yeah i have the oval carbs that are the paita 32/34 solexes idk whats the difference between 32/34 since i see tHe 32 vers on the pontons. Idk i might be wrong i have no idea still bout em. I recently placed a clear inline filter and yeah there is fuel flowing nice n clear to the carbs. What is idle at starter speed? How do i check that? Also i think i remember you sending me the link bout it but im going to stick to my motor for now

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