‘73 20hp carb help

JasonB

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Joined
Feb 10, 2003
Messages
1,471
Picked up the motor in the title. It has a BA-1A carb. I bought a rebuild kit and found a couple differences. 1- the carb as I got it seemed to have 2 fuel diagrams in the pump. Kit came with one, so that’s what I put back in. 2- The kit, which was listed as a Tillotson kit for this carb included a new needle. It’s a different style. The one in the carb is longer with no spring. The new one is shorter with a spring on top. I put it in and adjusted the float so the seam is parallel to the body when holding it upside down. The drop is maybe 1/2-3/4”

I put everything together and it runs, but is far from right. It will start, but will only run at a fast idle and eventually Boggs out unless I work the throttle a bit.

Should I be concerned about the different style needle and what should the float adjustment be?

It ran better before rebuild, even with trash in it.
 

jimmbo

Supreme Mariner
Joined
May 24, 2004
Messages
14,238
A Serial # for the Motor would make it easier to find which Carb Kit is required
The Rebuild Kit you purchased, was it a Genuine Mercury/Quicksilver Kit, or a 3rd Party Kit?
Also when you reinstalled the Carb, did you verify the Sync between the Carb, and the Ignition Advance?

What condition, mechanically, is the Engine in?
Compression #s?
Can the Spark on both Plug Wires, jump a 7/16" Gap?
 

JasonB

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Feb 10, 2003
Messages
1,471
3rd party kit. I think I found the root issue digging around rebuild videos on YouTube. The Merc kit includes the same “new” style needle with a note that it isn’t compatible with the BA-1A and some others. I’ll swap it back, reset the float, and see what happens.

Spark is good, compression seems good, but I haven’t put a gauge on it. It ran ok before, but I wanted to refresh the carb and make sure there was no trash or corrosion in it.
 

JasonB

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Joined
Feb 10, 2003
Messages
1,471
Confirmed with a twist. I put the original needle back in, readjusted the float, and discovered I left the small jet out of the side of the pick up tube. Put it back together, it started fairly easily, Adjusted the idle mix and it’s running as it should.
 
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