Rebuilt early model 61 Zenith carb

[67c&ccorv]

Well...the Ebay bug finally got to me.

I had been following an ad on Ebay for some months now advertising a rebuilt "Zenith carb for Palmer/Atomic 4" marine engine.

It looked so good that after some discussion with the seller I decided to buy the unit outright. When it arrived in the mail I was struck by the beauty and precision of the rebuild - complete from top to bottom including throttle and carb plate bushings.

However, upon investigation it turns out that this is not a "marine carb" but a model 61 from some other engine and lacking in angled intake bell and scavenge tube for unburned fuel...which is a Coast Guard requirement.

So...now to turn it into a marine carb and at the same time modify my mechanical fuel pump (as I got some nice new components from MMI ) so that in the event of a failed diaphragm the pump will not pump fuel into the crankcase of our beloved Atomic 4.

I have an idea on how to go about this (a few more parts from MMI) but would welcome any comments from Afourians.

[Dave Neptune]

Whoa, be sure

67, on the 61 series carbs the scavange tube is internal. It feeds from a port in the throat to carb flange base. Doublecheck for that.

Dave Neptune

[67c&ccorv]

Done Dave...it isn't there.

The Zenith M61 Marine carb was a special item and the illustration in the manual I have also shows them with out the angled intake but with the internal scavenge tube.

Zenith made many M61's...some were for marine - others for auto, tractors etc.

There is even a cast iron M63 with an accelarator pump for marine service!

[Dave Neptune]

2nd plug?

67, what is the plug plugging that is offset from the centerline of the carb. One is to the "bowl", what is the other one plugging?

I was always under the impression that the "M" designation was for marine apps. I'll need to check that out.

Dave Neptune

[sastanley]

Dave...any correlation between this and the other carb thread we have running with no scavenge tube? I don't know enough about visual cues on the carbs to determine if there is any difference.

link to Tim's thread - http://www.moyermarine.com/forums/showthread.php?t=7769

67..that looks real nice...hope you get the bits worked out!

[67c&ccorv]

67, what is the plug plugging that is offset from the centerline of the carb. One is to the "bowl", what is the other one plugging?

I was always under the impression that the "M" designation was for marine apps. I'll need to check that out.

Dave Neptune

That is a float bowl drain plug Dave.

The carb is a Zenith M61 number plate #S821 which according to the Carb Doctor was made for Palmer motors and is designated 61M2AE7.

Still no internal scavenge tube that I can see...nor any drilled internal pickup passage either.

But that's OK because we have a plan.

[Dave Neptune]

The 2nd plug?

67, yes one plug is for the bowl drain but what is the other? Looks like the right spot for the scavange tube hook up if external. Take a look inside and see if the passage goes to the mounting flange base. I'm really curious about this. Is it a smaller diameter venturi than the one for the A-4's?

Dave Neptune

[67c&ccorv]

67, yes one plug is for the bowl drain but what is the other? Looks like the right spot for the scavange tube hook up if external. Take a look inside and see if the passage goes to the mounting flange base. I'm really curious about this. Is it a smaller diameter venturi than the one for the A-4's?

Dave Neptune

It is an external scavenge tube hookup...very unusual because all of the marine M61's I have seen have the internal scavenge tube which reaches down into the well at that location.

ID of the intake is 1.230" - OD of the intake is 1.5" - I/D of throttle uptake is 1.015" - stud C-C is 2.25".