ArdWrknTrk Posted August 9, 2019 Share Posted August 9, 2019 Never touched the Cam, Just did the timing chain. Cam dot to Crank Key/dot, I held the carb very close to WOT with hood open and watched the new clear-plastic fuel filter 2" from the carb, it never lost any volume (gas almost to the top) the whole time it was at WOT. Held it WOT for over 30 seconds, Screamed fine. But step on it with a load, and nothing hits the road, Got to be a carb thing, brand new Autolite plugs, black carbon on #1 plug today. Yeah, but under NO load. You don't think the secondaries or power valve being open has any effect???? I don't trust Autolite in a lawnmower , personally... I swear by NGK, until I see their screwups too. Link to comment Share on other sites More sharing options...
Steve83 Posted August 10, 2019 Share Posted August 10, 2019 Never touched the Cam, Just did the timing chain. Cam dot to Crank Key/dot, I held the carb very close to WOT with hood open and watched the new clear-plastic fuel filter 2" from the carb, it never lost any volume (gas almost to the top) the whole time it was at WOT. Held it WOT for over 30 seconds, Screamed fine. But step on it with a load, and nothing hits the road, Got to be a carb thing, brand new Autolite plugs, black carbon on #1 plug today. Sounds like base ignition timing (including the distributor being a tooth off or plug wire routing) to me. Link to comment Share on other sites More sharing options...
reamer Posted August 10, 2019 Author Share Posted August 10, 2019 Sounds like base ignition timing (including the distributor being a tooth off or plug wire routing) to me. So today I pulled the #1 plug to check TDC and Rotor location. On the compression stroke, Rotor lines up nicely on #1 But the plug (with about 2 hours service on it) was full of black powdery carbon. Pulled all the plugs,- all Carbonized.... Pulled Eddy carb, inside the intake is wet with gas. So it has a lifetime warranty on it from National Carbs in Florida, so I'll send it out Monday but I fear I'll lose most of the rest of the driving season.. Link to comment Share on other sites More sharing options...
85lebaront2 Posted August 10, 2019 Share Posted August 10, 2019 So today I pulled the #1 plug to check TDC and Rotor location. On the compression stroke, Rotor lines up nicely on #1 But the plug (with about 2 hours service on it) was full of black powdery carbon. Pulled all the plugs,- all Carbonized.... Pulled Eddy carb, inside the intake is wet with gas. So it has a lifetime warranty on it from National Carbs in Florida, so I'll send it out Monday but I fear I'll lose most of the rest of the driving season.. I had an AFB from a Buick 300 V8 that as near as I could tell had a hairline crack in one float bowl, ran good, but would leak gas on the intake overnight. Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 11, 2019 Share Posted August 11, 2019 So today I pulled the #1 plug to check TDC and Rotor location. On the compression stroke, Rotor lines up nicely on #1 But the plug (with about 2 hours service on it) was full of black powdery carbon. Pulled all the plugs,- all Carbonized.... Pulled Eddy carb, inside the intake is wet with gas. So it has a lifetime warranty on it from National Carbs in Florida, so I'll send it out Monday but I fear I'll lose most of the rest of the driving season.. Perhaps one float is sinking? Or, as Bill suggested, there's a crack or hole in the casting. In any event, a very rich condition can cause those symptoms. Let's hope that is it. But, you do have a fuel pressure regulator on, right? Too much pressure can overpower the floats and cause a rich condition. However, that usually only happens at idle unless you have a really strong fuel pump. Link to comment Share on other sites More sharing options...
reamer Posted August 11, 2019 Author Share Posted August 11, 2019 Perhaps one float is sinking? Or, as Bill suggested, there's a crack or hole in the casting. In any event, a very rich condition can cause those symptoms. Let's hope that is it. But, you do have a fuel pressure regulator on, right? Too much pressure can overpower the floats and cause a rich condition. However, that usually only happens at idle unless you have a really strong fuel pump. Stock mechanical fuel pump, and regulated to 7psi (at least that's what the regulator shows) Link to comment Share on other sites More sharing options...
Gary Lewis Posted August 11, 2019 Share Posted August 11, 2019 Stock mechanical fuel pump, and regulated to 7psi (at least that's what the regulator shows) You might crank it down to 5 or lower to test. Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 11, 2019 Share Posted August 11, 2019 You might crank it down to 5 or lower to test. I've never had problems with my mechanical fuel pump overpowering the floats in my AVS, the stock 4180, the 0-80457 S, or the 4160's in 600 & 750 cfm. A blown power valve would clear up under acceleration and pop on trailing throttle. A sunk float would flood at idle and clear up too. I don't understand how it could be running rich -and- bogging on open throttle, unless the secondaries are delivering way too much fuel. That is the only carburetor issue I could see doing this. Are you sure the coil is giving good spark under load and higher rpm's? Link to comment Share on other sites More sharing options...
reamer Posted August 12, 2019 Author Share Posted August 12, 2019 I've never had problems with my mechanical fuel pump overpowering the floats in my AVS, the stock 4180, the 0-80457 S, or the 4160's in 600 & 750 cfm. A blown power valve would clear up under acceleration and pop on trailing throttle. A sunk float would flood at idle and clear up too. I don't understand how it could be running rich -and- bogging on open throttle, unless the secondaries are delivering way too much fuel. That is the only carburetor issue I could see doing this. Are you sure the coil is giving good spark under load and higher rpm's? Not sure how to test a coil... Link to comment Share on other sites More sharing options...
ArdWrknTrk Posted August 12, 2019 Share Posted August 12, 2019 Not sure how to test a coil... You can feel if it gets very hot when running. If you were getting NO spark I would test primary and secondary windings for their resistance and continuity. I see the coil as a wear item (like points were) and replace it every decade or so, even if It appears fine. A good coil is around $30. https://www.summitracing.com/parts/smp-fd476 Link to comment Share on other sites More sharing options...
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