Oliver Super 77 - Carburetor Replacement

[dmsimmons69]

Looking for opinions on the Zenith carburetor replacement for my Oliver Super 77!! I have rebuilt my Marvel-Schebler TSX, but it still doesn't seem to be working well. I can't get it to idle without the choke on a little and then increasing throttle is a challenge as well. Anyway, looking for reviews on the Zenith carb...

 

[Oliver owner]

Looking for opinions on the Zenith carburetor replacement for my Oliver Super 77!! I have rebuilt my Marvel-Schebler TSX, but it still doesn't seem to be working well. I can't get it to idle without the choke on a little and then increasing throttle is a challenge as well. Anyway, looking for reviews on the Zenith carb...

I had the same issue with my S77. It has the Zenith. Ended up being the distributor shaft and bushings were worn out and caused the points gap to change while it was running. It needed choke to idle and would die if I throttled it up too fast. I'd make sure everything on the ignition side is all working correctly before replacing carb. Check timing with a timing light as well. As for a replacement, they are hard to find. You will probably need to go to a salvage yard. Zenith model 11580 is what the S77 used.

try calling maibach tractor parts or all states Ag parts

 

[greg krush]

I would agree with oliver owner, check all other issues, ignition, air leaks, air intake, marvel schebler carbs are simple and work well if everything else is good.

 

[scootergmc]

Normal diagnosis needs to ensue: Entire fuel system clean? Air intake system clean? Ignition system good? What led to the carb rebuild? Did you adjust it according to the manual? Governor good and adjusted correctly? So on so forth...

 

[dmsimmons69]

I had the same issue with my S77. It has the Zenith. Ended up being the distributor shaft and bushings were worn out and caused the points gap to change while it was running. It needed choke to idle and would die if I throttled it up too fast. I'd make sure everything on the ignition side is all working correctly before replacing carb. Check timing with a timing light as well. As for a replacement, they are hard to find. You will probably need to go to a salvage yard. Zenith model 11580 is what the S77 used.

try calling maibach tractor parts or all states Ag parts

Thanks for the info. I found a Zenith carb, so no issue there, but now I'm wondering about the timing since you had the exact same issue! I haven't used a timing light in decades, and that was on cars anyway. How do I get a timing light into position on the tractor when there's barely any room? Appreciate the help!

 

[dmsimmons69]

I would agree with oliver owner, check all other issues, ignition, air leaks, air intake, marvel schebler carbs are simple and work well if everything else is good.

Definitely checking the timing, but everything else is good, as far as I can tell! This tractor sat idle for over 5 years (inside), so I replaced all electronics and wiring. Fuel was drained long ago, so it didn't sit with fuel in it (ran ethanol free as well).

 

[dmsimmons69]

Normal diagnosis needs to ensue: Entire fuel system clean? Air intake system clean? Ignition system good? What led to the carb rebuild? Did you adjust it according to the manual? Governor good and adjusted correctly? So on so forth...

Thanks for the reply... Fuel system clean (tank to carb). Air intake system is clean. All electronics were replaced, including wiring. The carb rebuild was just due to the fact the tractor sat for over 5 years (inside), so I wanted to start fresh. Yes, to the best of my ability I adjusted the carb. Not sure how to diagnose the governor, so any help there would be appreciated!!

 

[scootergmc]

Thanks for the reply... Fuel system clean (tank to carb). Air intake system is clean. All electronics were replaced, including wiring. The carb rebuild was just due to the fact the tractor sat for over 5 years (inside), so I wanted to start fresh. Yes, to the best of my ability I adjusted the carb. Not sure how to diagnose the governor, so any help there would be appreciated!!

Take a look at this video- he has a series of previous rebuild videos but he has the same issue toward the end:

 

[greg krush]

Thanks for the reply... Fuel system clean (tank to carb). Air intake system is clean. All electronics were replaced, including wiring. The carb rebuild was just due to the fact the tractor sat for over 5 years (inside), so I wanted to start fresh. Yes, to the best of my ability I adjusted the carb. Not sure how to diagnose the governor, so any help there would be appreciated!!

Basic adjustment on the carb is turn out 1 1/2 turns on both idle and main jet, then adjust from there by ear, if you have to choke to get it to run it is short on fuel and when you choke it it is increasing vaccum and sucking in more fuel so either you need more fuel or less air leakage, to check for air leaks spray wd40 around any place air can leak in and see if any change in engine speed,
timing hole is on right side of engine behind steering column, turn engine to find mark and paint it for easier viewing. I time by ear, turn distributor to where it runs fastest and back off till it lugs just a bit. Governor linkages can stick, make sure linkages all the way from throttle handle to the governor and back to the carb are free and not bend and binding. if your only issue is idle it is probably not governor

 

[dmsimmons69]

Take a look at this video- he has a series of previous rebuild videos but he has the same issue toward the end:

Great, thanks for the link!!

 

[scootergmc]

Great, thanks for the link!!

No problem!

 

[dmsimmons69]

No problem!

I was starting to lean towards the timing, but after watching this video, it seems it still could be the carb! I might clean it again and see if I can get the main jet out...it's the only part i wasn't able to replace on the rebuild. If I am unable to get it out, I do have a local tractor repair shop that will rebuild it for me.