Carb Rebuild -- Suggestions for where to go

I need to get my carb rebuilt. It's a Marvel MA4-5 off an O-540.
Somehow it floods to the point of not running (longer story possibly
in another post). I'd like to find out why this is happening so that
besides just getting an overhaul I actually know it won't flood again.
I don't care if it costs extra for the diagnostic as long as I know
who I'm dealing with will find the problem to whatever extent this is
possible.

Any suggestions on reputable shops and previous experiences would be
greatly appreciated.

Thanks in Advance for any replies.
z

In article ,
zatatime wrote:
Any suggestions on reputable shops and previous experiences would be
greatly appreciated.


I had my carb rebuilt by Mattituck several years ago, and was pleased
with the result.



JKG

Does it leak gas when "flooding"? Or does it just go too rich. One
possibility is you have a float with a leak in it. This will make the
carb run rich and even leak due to overflow. Just an idea.

Just get a mechanic and have him take it apart. There is some FAA
thing, but if you send it out for overhaul, theres no biggie. He can
take it apart, just cant put it back together. Some mechanics can put
them back together though. I dunno, all that FAA stuff but there is an
issue there. Some mechanics work on carbs and some don't. Find one that
will. Have him take the bottom off the carb, check the workings out,
find out whats wrong and fix it. Ask around.

I know what you mean about wanting to find the problem. That way you
make sure it gets fixed. Otherwise its just some kid in a shop who
could care less.

Go here for best prices: www.aircraftspruce.com.

On 11 Jan 2006 18:36:21 -0800, "Doug"
wrote:

Does it leak gas when "flooding"? Or does it just go too rich. One
possibility is you have a float with a leak in it. This will make the
carb run rich and even leak due to overflow. Just an idea.

Just get a mechanic and have him take it apart. There is some FAA
thing, but if you send it out for overhaul, theres no biggie. He can
take it apart, just cant put it back together. Some mechanics can put
them back together though. I dunno, all that FAA stuff but there is an
issue there. Some mechanics work on carbs and some don't. Find one that
will. Have him take the bottom off the carb, check the workings out,
find out whats wrong and fix it. Ask around.

I know what you mean about wanting to find the problem. That way you
make sure it gets fixed. Otherwise its just some kid in a shop who
could care less.


When I got it back on the ground and looked, gas was running out of it
like crazy! Fuel pressure went up to about 10psi with the electric
pump on and normal is around 6+. I didn't have a flashlight, but it
looked like it was running out of both the main jet and the
accelerator jet when the fuel pump was turned on.

Short version of my mechanic situation: The guy I've worked with for
15 years died in July. He could fix anything, and I have no doubt I'd
have already learned the cause if he was still around. I do have a
mechanic (who was with me when it quit), but he mostly does
restorations, not repair. We took it apart and the float seemed fine.
I will check that out further though by submersion. Our thoughts are
that something either caused the float to hang up, or something is
going on in one of the chambers we can't analyze. I don't know how
the accelerator pump works well enough to know if something goes wrong
with it if fuel could flow through easily causing this flooding
condition.

Thanks for your reply, and all others who have responded. I'm open to
comments from anyone who may have good knowledge about this situation.

z

In article ,
zatatime wrote:

On 11 Jan 2006 18:36:21 -0800, "Doug"
wrote:

Does it leak gas when "flooding"? Or does it just go too rich. One
possibility is you have a float with a leak in it. This will make the
carb run rich and even leak due to overflow. Just an idea.

Just get a mechanic and have him take it apart. There is some FAA
thing, but if you send it out for overhaul, theres no biggie. He can
take it apart, just cant put it back together. Some mechanics can put
them back together though. I dunno, all that FAA stuff but there is an
issue there. Some mechanics work on carbs and some don't. Find one that
will. Have him take the bottom off the carb, check the workings out,
find out whats wrong and fix it. Ask around.

I know what you mean about wanting to find the problem. That way you
make sure it gets fixed. Otherwise its just some kid in a shop who
could care less.


When I got it back on the ground and looked, gas was running out of it
like crazy! Fuel pressure went up to about 10psi with the electric
pump on and normal is around 6+. I didn't have a flashlight, but it
looked like it was running out of both the main jet and the
accelerator jet when the fuel pump was turned on.

6 to 10 psi on a MA 4-5? 6 psi is the test pressure to check for leaks;
operating pressure is 3-5 psi. No wonder the fuel was running out the
bowl!




Short version of my mechanic situation: The guy I've worked with for
15 years died in July. He could fix anything, and I have no doubt I'd
have already learned the cause if he was still around. I do have a
mechanic (who was with me when it quit), but he mostly does
restorations, not repair. We took it apart and the float seemed fine.
I will check that out further though by submersion. Our thoughts are
that something either caused the float to hang up, or something is
going on in one of the chambers we can't analyze. I don't know how
the accelerator pump works well enough to know if something goes wrong
with it if fuel could flow through easily causing this flooding
condition.

Thanks for your reply, and all others who have responded. I'm open to
comments from anyone who may have good knowledge about this situation.

z

--
Remve "_" from email to reply to me personally.

Typical problem here is the float valve. It becomes flattened on the
cone surface. Replace the float valve and it will be OK. May need to
adjust the float height also.

If you/your mechanic do decide to look at float level, first make a
fixture to show the operating float level.

Drill a small hole thru a 1/8 inch dia NPT pipe plug, and epoxy a 1 ft
length of clear flex tubing (such as model airplane fuel line) into the
hole.

There is a 1/8 inch (I think) NPT pipe plug on the back of the carb
that is ported into the bowl. Remove this plug & screw the fixture
plug into this port. Hold the tubing up to see where the float level
actually settles - and decide from there.

If you/your mechanic do decide to look at float level, first make a
standpipe
fixture to show the operating float level.

Drill a small hole thru a 1/8 inch dia NPT pipe plug, and epoxy a 1 ft
length of clear flex tubing (such as model airplane fuel line) into the
hole.

There is a 1/8 inch (I think) NPT pipe plug on the back of the carb
that is ported into the bowl. Remove this plug & screw the standpipe
fixture
plug into this port. Hold the tubing up to see where the float level
actually settles - and decide your next course of action from there.

Obviously this fixture is for ground testing only.

FWIW - A fellow I know with a 182 had a similar carb rebuilt & had
quite an ongoing runaround with the certified repair station that did
it. There is a seal on the throttle shaft that if omitted or damaged,
ports intake manifold vacuum to the float bowl area. He was having
trouble with excessively lean mixture. I know this is not your problem
- but just be forwarned that a CRS doesn't necessarily get things right
either.

Reply

Give a call to
Mike's Fuel Metering Service
Tulsa Oklahoma

tel: 918-838-6217


Kent Ok



"zatatime" wrote in message
...
I need to get my carb rebuilt. It's a Marvel MA4-5 off an O-540.
Somehow it floods to the point of not running (longer story possibly
in another post). I'd like to find out why this is happening so that
besides just getting an overhaul I actually know it won't flood again.
I don't care if it costs extra for the diagnostic as long as I know
who I'm dealing with will find the problem to whatever extent this is
possible.

Any suggestions on reputable shops and previous experiences would be
greatly appreciated.

Thanks in Advance for any replies.
z