1973 merc 7.5 thunderbolt KB12A carb parts

[jeff1974]

Hi guys,
i have a merc 7.5 SN# 3375295 that i need to rebuild the carb in. Its a KB12A. I had it apart and noticed the idle tube has a crack in it. I think its a common problem from what i have read, but i cant seem to find a part number for it and nobody seems to have one. Everyone says its been discontinued.
Is there an aftermarket or something available?
I dont really want to buy a used carb of ebay or one of those places because you never know what you get until you dig in to it.
I thought if i was going to get any help on this you all would be the ones to talk to
It seems to run ok with the crack in it, but i would rather be safe than stuck with a paddle in hand and a sweaty forehead from trying to make it back to shore.
Thanks so much for any help

 

[tpenfield]

:welcome:

Not sure you will find anything new. . . probably only used. after a bit of googling, looks like the carb is a "Tillotson" brand carb. that extra search term *may* help. I would go with what you can find, even if used.

 

[60sboater]

The "bay" might be one of the few places to find one. I've bought some parts from there (no carbs though) and they've been "as represented" in the ads.

 

[jeff1974]

Thanks for the replies .I was afraid of that being my only option. Even if i could find a part number for it, it might help in the good ol google search, but it seems like all of the parts diagrams just show it as a part not a part number GRRRRRR.
One more question that maybe someone can help with.
If i cant find a replacement and keep running it like it is, will it keep running or eventually start sucking air and never run again? I guess im a little confused on the idle tubes job.
Thanks again for all the help

 

[tpenfield]

Sort of depends . . . I cannot remember if the carb has a main jet/needle as well as an idle jet . . or not. anyway. if it works, leave it be. Usually the idle jet is just a regulated air leak. So, if it cracked, it may not have a negative effect.

Would you post a few pictures of the carb & cracked location as that will help.

 

[jeff1974]

I wish i would have taken some pics when i had it apart. The only problem now is that its working and im scared to death that if i take it apart again to get some pics it will never work again. Thats usually how my life works
If i decide to be brave (or stupid as my wife says) i will pull the tube this weekend and snap a couple shots