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 Post subject: Near disaster from carb
PostPosted: Mon May 15, 2017 10:24 pm 
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I've been trying to figure out why my car has been running rough after about 2 miles of driving. Have adjusted valves, checked timing (have Pertronix ignition), changed the coil, and finally changed the spark plugs last night. Took her out for a spin and after 4 miles she was still running great and I thought problem solved. As I took the victory lap, sure enough she started skipping badly. I gave up for the night and put her to bed in the garage and after struggling with those short brown plug connectors, I ordered a set with the long brown ones.

Today my wife called me at work to tell me she smelled gas in the house. I thought she was imagining it but got home to find it dripping gas from the left side. There were big puddles on the floor. I rolled the car outside and took the air cleaner off and both bowls were full to the brim overflowing. What a disaster this could have been had there been some spark in the closed up garage!

Can I assume it is the needle valve getting stuck open? Was this likely the cause all along of my rough running engine when hot?

Should i just have both carbs rebuilt? Or just change out that needle valve? If rebuilding is recommended, should I look for a local guy or send them away to an 356 Solex specialist? While I usually would want to do most things myself, I probably had just as soon send these out to a trushworthy Registry recommended member...

Thanks in advance for your advice.
Mitch (the Bad News Bear of the 356 Registry... :)

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PostPosted: Mon May 15, 2017 10:55 pm 
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Yes probably float needle valve stuck and leaving the fuel lever on which is a big NO NO. If it was running fine with stable idle before just take off both air cleaners, start it and look down the carb throats. The one with gas flowing in it is the culprit. Easy to remove cover and replace float valve. Don't over tighten when putting back together. If it has never run well or if it has always had an unstable idle(sign of throttle shaft wear) then probably time to rebuild correctly. I have 2 356s with Solex carbs. I would send them out for rebuild if they need it. Carb Rescue or Bruce Smith in the Vendors section both do a good job. Your oil is contaminated at this point and if you are lucky you haven't done any internal damage by driving with gas diluted oil. Don't start the car until you have changed the oil at the very least.

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PostPosted: Mon May 15, 2017 11:00 pm 
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Guys: He shouldn't try to turn it over without removing the spark plugs on that side, Hydrolock, right? Disconnect the coil wire also.

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PostPosted: Mon May 15, 2017 11:05 pm 
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Correct Mike. I would also suggest you remove the sump plate when you change the oil and see what the magnet has on it and check the old for metallic particles. Worst case scenario is an expensive rebuild from internal damage from contaminated oil. Keeping my fingers crossed for you. The one time I had a stuck float needle valve it even ran poorly when started. So I don't understand why it would take a few miles to start running poorly. Maybe others will chime in.

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PostPosted: Mon May 15, 2017 11:48 pm 
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Great suggestions. First thing I did was disconnect the battery. I will not even rotate the engine before changing the oil, which I was about to do anyway. I'm leaning toward just sending both carbs in for a rebuild, I have not driven the car nearly enough in the last couple of years, and I know that sitting is the worst thing for these old jewels. I'm determined to make it a daily driver now, don't care what it costs to get it up an running right, but still will do everything I can -- within reason -- myself. With your help, of course!

thanks again.
mitch

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PostPosted: Tue May 16, 2017 1:17 am 
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Mitch, there is an article in the last Registry addressing exactly this condition. Can I suggest you read it?

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PostPosted: Tue May 16, 2017 3:00 am 
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Ron LaDow wrote:
Mitch, there is an article in the last Registry addressing exactly this condition. Can I suggest you read it?


This is where it would be good to be able to link to the last mag but there always seems to be a delivery for it getting on line?


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PostPosted: Tue May 16, 2017 7:08 am 
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Mitch -

Best case scenario is that you put it away before any damage was done. Has it been running poorly after a few miles for a while? That may have been the time it had taken to overfill the float bowl(s). Remove the dipstick and check if the oil smells like gas. That may ease your mind or increase your worries. Good luck.

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PostPosted: Tue May 16, 2017 7:20 am 
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neilbardsley wrote:
Ron LaDow wrote:
Mitch, there is an article in the last Registry addressing exactly this condition. Can I suggest you read it?


This is where it would be good to be able to link to the last mag but there always seems to be a delivery for it getting on line?


Dang. I have the most recent hardcopy volume but not that one -- due to a membership lapse. Can't keep up with all of my professional and hobby memberships. Hopefully the web version will be out soon. Thanks for the heads up, Ron.

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PostPosted: Tue May 16, 2017 8:30 am 
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Not only will the oil smell like gas but level will probably be higher than usual.

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PostPosted: Tue May 16, 2017 8:54 am 
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Bruce Smith wrote:
Mitch -
Has it been running poorly after a few miles for a while?


Yes, this has plagued me for months, and prevented me from driving the car other than around the block.

Bruce Smith wrote:
That may have been the time it had taken to overfill the float bowl(s).


After I took the air cleaner off and suctioned out the gas with a turkey baster, the bowls would fill back up within about 10-15 minutes. It took me a while to figure out that the handle under the dash wasn't really "auf" until it was completely CCW, not pointing at the word "auf". This little tidbit would have saved me some cursing... but learning don't come easy!

Bruce Smith wrote:
Remove the dipstick and check if the oil smells like gas. That may ease your mind or increase your worries. Good luck.


Roger that... along with the dipstick level mentioned by Doug. Would not have thought to check these things-- thanks!

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PostPosted: Tue May 16, 2017 8:59 am 
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I sounds to me like you could be getting crud sucked up into the carbs from your fuel tank. What state is the tank in ? Has it been steam cleaned or relined in living memory ? If not how does the 'roof' of the tank feel inside ? Could it be rusty ?

Condensation forms on the inside of fuel tanks and the resulting oxide falls into the fuel as a very fine powder which will find it's way through most filters. Normally this fine grey powder sits in the bottom of your tank but can, after a couple of miles spirited driving, find it's way through to the carbs and cause lumpy running. Let the car sit and the silt settles, giving you another couple of trouble free miles next time you drive.

Sounds like this time, some of the crud has found it's way into a needle valve and wedged it open.

The other thing that made my carburetors piss fuel all over the floor was a leaking float. A cursory inspection showed the floats to be floating but then weighing the floats revealed that one was carrying it's own weight in fuel and not bobbing as it should. Cue one hydrolocked engine.

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PostPosted: Tue May 16, 2017 9:29 am 
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"Auf" is ON. "ZU" is OFF (fully CCW). "RES" is self-explanatory. IF you have a gas-fired water heater in the garage, or any other flame or spark source, push the car outside before trying to get the fuel out of the cylinder(s). Remove the plugs and then turn the engine over backwards to get the liquid out.

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PostPosted: Tue May 16, 2017 9:34 am 
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Tank has not been cleaned or relined ever by me, but looks to be in decent shape -- but knowing what I know now I should look more closely.

This brings up another observation... I don't see an inline filter anywhere! I've looked under the car in the rear and had that on my list of things to do during my recent flurry of maintenance. Guess that should have been higher on the list. I have read lots of other threads about it but have not decided what type and where to splice it in.

I'm leaning more and more toward complete rebuilds of both carbs... if a needle valve is clogged, then seems like other things could be also.

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PostPosted: Tue May 16, 2017 9:46 am 
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Wes Bender wrote:
"Auf" is ON. "ZU" is OFF (fully CCW). "RES" is self-explanatory. IF you have a gas-fired water heater in the garage, or any other flame or spark source, push the car outside before trying to get the fuel out of the cylinder(s). Remove the plugs and then turn the engine over backwards to get the liquid out.


"Auf is ON"... Well that was counterintuitive, and I blame my german-american wife for not knowing this! I asked her what "off" in german was and she said "a-u-f". Wow, good to know! She will be appropriately chastised.

The car is exiled from the garage until I get all this straightened out. Bummer to know that I have to take those damn plugs out having just replaced them! I have big hands and it was a bitch -- as many know. And thanks to Dan Metz for a good article about that.

Would you be kind enough to explain what backwards is better?

Thanks Wes!

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