Inliners International Forums General Discussion Engines Leaking rochester 1 barrel BC carb

I'm having fun! I'M HAVING FUN! HONEST!

My 235 is finally running great now that I re-build the two rochester BC carbs. The bad news is the carb closest to the firewall leaks. It fills up with gas while running, runs okay but after I turn it off gas leaks out of it until the bowl is empty. How do I troubleshoot the leak?

Thanks in advance,

Ted

#4730

Does the carb bowl really get empty? If so there must be a hole (no kidding) or rather a crack or maybe a warped gasket surface below the bowl at the cast iron carb base. Or perhaps a little ball check has been lost or not in its proper place.

Find a good parts illustration(I think there might be some on this site?), or in a rebuild kit, and look for all these ball checks-may be the one in the accellerator pump. Most of them have a fine gage wire spring that loads them in place, They usually stop fuel flow and they are soooo easy to lose (the ball checks are easily lost too-they look like chrome b-b's). Dont ever think you can take a carb apart while sitting under a tree! These are the pieces that cause a wave of panic when a carb is opened up and turned upside down (where'd that come from??), if you can even find them in the dirt. Been there, done that... (etc).

You're right, the bowl is not empty, it is 1/4 inch below the rim of the center section. I changed out, and adjusted the float from another carb while leaving the fuel in the bowl. I verified that the gasket surfaces meet evenly. But fuel leaks below the bowl where the shaft goes through the body when I tip the carb off parallel to the floor. How do I tell if the shaft is worn out?

Appreciate the help!

Ted

i'm doing this from memory -dont have a picture in front of me. I think the float bowl is leaking fuel and it runs onto the butterfly shaft and then runs off the ends of the shaft, problem is how it gets to the shaft in the first place.

Old carb's shafts are usually brass and will wear with age- but the usual problem with worn shafts is they will leak vacuum, not fuel because any fuel hitting them will be sucked down the intake when motor is running. But you can open the trottle and grab the butterfly and move it around while looking at the end of the shaft- you will be able to see if there is play. I have drilled out the shaft hole in the cast iron and hammered/ epoxied in a brass tube of the proper id to fix worn out cast iron body, if the shaft (most likely since its the softer metal) is where wear is (remove the butterfly and then pull out the shaft-looking for a "stepped" area where the shaft touched the cast iron) then you must replace or fabricate a new shaft, or find a lesser worn shaft from another carb.

if the fuel level is too high (from a non seating float needle/seat valve) then at idle raw fuel can spill down into the venturi area of the carb. At idle the fuel spillage maybe enough to run out the throttle shaft, but it would have a terribly rich idle with a good deal of eye-watering black smoke out the tailpipes.

Just ideas off the top of my head at the moment, will try to find good model BC picture in my Rochester carb book by Doug Roe. He had good words/pictures of this old carb (a little strange by todays-oops-later designs).

Wahoo!

I fixed it, it's stopped leaking!

I replaced and re-set the brass float and then leveled out the joint between the top and center section. A friend looked at the carb and realized the top and center portion did not match, the upper piece was (very slightly) bowed / gapped in the middle (between the screws at the corners) in relationship to the center section. I got some 220 grit sandpaper and using cutting fluid sanded the pieces while the sandpaper was laid out on a sheet of glass. Took a bit off the top and center until the gap looked close enough for the gasket to be compressed. It worked!

Thank you so much for helping! The tune-up happens this weekend, out in the driveway!

Ted