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TOPIC: Just "floating" a theory...

Just "floating" a theory... 14 years 5 months ago #11395

My boat, which I bought less than 2 weeks ago is a 1960 Lone Star Monterey. It is powered by a 1960 Merc 300 which provides 35 horsepower.
Today my wife and I took it to the lake for a shakedown cruise. It had been serviced but today would not remain running. I noticed a considerable amount of gas or oil on the water. Needless to say, we aborted our plans and returned home.
Once home, I had a better chance to look the engine over. I filled a garbage can with water and started the engine. I once again got it started, but couldn't keep it running. I noticed a fuel leak at the gasket for the fuel bowl on the lower carb.
I made a new gasket and re started the engine. At first, things seemed better, but then I noticed fuel once again leaking from the lower carb. specifically from the shaft that turns the throttle plate (butterfly). This seems an odd place for a fuel leak. I gave up as it was now above 100 f.
Tonight it occured to me that the float may have stuck or sunk. Does this seem a viable explanation of my woes? Are there other possibilities?
If it is the float, should I try to have it re soldered or are replacements available?

Bill von Tagen
Boise, Idaho

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Re:Just "floating" a theory... 14 years 5 months ago #11396

Stuck floats are definitely a possibility.

Given that you had bad seals from the get-go, id say they should be pulled off and given a complete going through.

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Re:Just "floating" a theory... 14 years 5 months ago #11427

The floats are either cork or plastic. Neither can be repaired - simply replace them if you question their condition.
Both the floats and the needle and seat (which usually cause this issue) are NLA for the Tillotson carbs you have, but might still be available through older large Merc dealers like Joe Pool Jr's who is a member of this forum.
Joe can be reached at: jdpjratatlanta at msn dot com.
Tim Calmes may also have these goodies.
He can be reached at: tcalmes2 at rochester dot rr dot com
Those NLA part number are:
Mercury # 1399-1138 (needle & seat assembly)
Mercury # 1399-110A1 (float)
You can also convert to the later 'Mercarb' tops and floats with parts still available.
To use the following parts you MUST convert to Mercarb tops and I have a bunch. The threads are different for the brass needle seat assembly so don't try and use them in your original tops.
Mercarb needle & seat assembly:
Merc part # 1395-83181 or Sierra Marine # 18-7061
Mercarb floats:
Merc part # 1395-8673 or Sierra Marine # 18-7208
Sierra Marine parts can be readily obtained through NAPA.
The other cause of this 'flooding' issue can be improperly adjusted float needle linkage. Initially this can be mistaken as the cause if you still have the original needle & seat assemblies installed because the rubber seat in the original set-ups gets mushy due to the alcohol in the gasoline we are confronted with today.
See the attached to set the linkage mentioned.
Contact me if you need the Mercarb tops.
frankenmerc at comcast dot net
Thom
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Re:Just "floating" a theory... 14 years 4 months ago #13131

The needle was stuck. I freed it and the problem disappeared. It has not reappeared.
We took the boat on vacation, and after some WD 40 on the throttle linkage, the boat performed like a champ! That 35 hp Merc 300 really moves the boat. The engine's performance and throttle responsiveness improved each day. I've adjusted the linkage and now have no complaints about the engine.
I will enjoy it until October 1st, then begin restoration of the boat. I hope to havbe it finished by June 1.
I've read the article on painting boats. Any tips on painting an old Merc engine? What about repainting the letters: "MERCURY"?
Bill von Tagen

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Re:Just "floating" a theory... 14 years 4 months ago #13213

  • Kerry
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Run a bit of Seafoam in the gas tank. Cleans carbs great. I run some every other tank.

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