flooding


mymgb
06-28-2006, 12:11 PM
my 75 continually floods leading to starting problems, as Im new to the mgb world, Im considering replacing the carb with something a little more reliable, it currently has a zenith with an auto choke...any suggestions?

Flash75
06-28-2006, 02:54 PM
Before spending lots of money on some different carburetors it's a good idea to try repairing what you have. The ZS carburetor is adequate and will run OK if it is in good condition. Changing to anything else will require a different exhaust manifold unless you try to find a SU HIF 6, expensive.

Below are two links that will help you sort out your problems.
http://www.paulbunyan.net/~jasko/choke/
http://www.triumphspitfire.com/carbs.html
I know one of the links is a Spitfire link but the carburetors are very similar.

I don't have recent hands on experience, so I'm going to ask John E. to contact you, he has an MGB with a working ZS carburetor that he sorted out with a few parts and some diligent work. John is very helpful and doesn't mind sharing his knowledge with others. Good luck.

Clifton

jdemgb
06-28-2006, 06:06 PM
mymgb,

I'm the John E. that Clifton referenced. I have a Zenith carb, and I've experienced the flooding you describe. Before I start spouting out solutions, could you tell me when is it flooding i.e. when you come to a stop light? When you're running? After you've stopped?

Also, do you have the mixture adjustment tool yet?

I hope I can help. My Zenith runs fine now without continuous adjustment. A lot of people will tell you to get another carb, but you'll have to have a new manifold and maybe some exaust modification, which can get expensive. You can probably sort out your problems in the short term fairly inexpensively, if you want to save some money, and then change it out later if you're still not satisfied.

I'll be glad to help if you want to take a run at it.

John

mymgb
06-29-2006, 10:56 AM
mymgb,

I'm the John E. that Clifton referenced. I have a Zenith carb, and I've experienced the flooding you describe. Before I start spouting out solutions, could you tell me when is it flooding i.e. when you come to a stop light? When you're running? After you've stopped?

Also, do you have the mixture adjustment tool yet?

I hope I can help. My Zenith runs fine now without continuous adjustment. A lot of people will tell you to get another carb, but you'll have to have a new manifold and maybe some exaust modification, which can get expensive. You can probably sort out your problems in the short term fairly inexpensively, if you want to save some money, and then change it out later if you're still not satisfied.

I'll be glad to help if you want to take a run at it.

John


Hi John...Thank-you for your time, It seems to flood when trying to start it, when it's warm cold it doesnt seem to matter, once it's running it's fine.

Rob

jdemgb
06-29-2006, 05:56 PM
Have you checked the mixture needle for flat spots yet? That's the first thing I'd do.

Also, check out this link:

http://www.theautoist.com/zs_water_chokes.htm

Look at the picture of the orientation of the waterchoke that he descibes. If its out of alignment, it can cause problems.

Once you're running, do you think you're running rich? Have you tried to adjust the mixture yet? If the needle doesn't have any flat spots, then adjust it to the point where the barrel of the needle is flush with the piston. That's your starting point. Richer is clockwise, leaner is counter-clockwise. I usually turn mine in half turn increments, and then take it for a drive. But don't try it without the mixture adjustment tool - about $20 at Moss.

Also, its a biased needle, meaning that its spring-loaded and points off center.

When you put the piston back in, its keyed by a small nipple on the diaphragm - be sure it fits in the slot on the piston.

Be careful with the rubber diaphragm while you've got the piston out. If it looks old (it will be very thin if its old) replace it. The diaphragm is about $5 and the needle about $20. Check your needle - it is probably a 45H, but it might be a 45G. If the one you've got is flat, I'd replace it with the same one.

One other thing it might be is your floats - I haven't had to adjust them yet - its a little bigger project. Check the other things. If they don't help, I'll get directions for float adjustment.

Let me know what you find out. If you need more information before removing the piston, I'll be glad to go into more detail.

John

MGBSS63
07-04-2006, 09:53 PM
Float can be out of adjustment or float itself could have pin hole and will never work right......float needle could be wore out replace with grose jet way better.... replace fuel filter or add one inline before carb to keep crap out of the float chamber..if fuel pump has been replaced recently could have too high of pressure..mixture needle could make it run rich but doesn't usually severely flood the car like you are describing.....if choke gasket is leaking it can cause flooding....choke out of adjustment or it's internal parts aren't working right could cause flooding....I've had an mgb catch on fire because of a flooding problem carry a fire extinguisher...mgbss63

Add your comment to this topic!