carb numbers

General discussion about our beloved Tercel 4WD cars
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hikersteve
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Posts: 55
Joined: Wed Nov 06, 2013 9:00 pm
My tercel:: 84 sr5 manual
Location: penn valley ca

carb numbers

Post by hikersteve »

im rebuilding stock carb and swapping from weber back to original
have two donors, one is 15340 and one is 15328
wondering what the difference is?
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dlb
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My tercel:: none currently, 7 previous
Location: bc, canada

Re: carb numbers

Post by dlb »

Is that on the little metal tag on the air horn? I don't think any of mine have still had that tag.

When you rebuild it and remove the jets, you will see numbers stamped on the jets that indicate their size (bigger #s = bigger holes). The one I just rebuild was 159 and 109 which seems pretty common. There is a bit of variety to the jet sizing though. No idea how they determined which cars got which jets.
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
Location: Arlington WA USA

Re: carb numbers

Post by Petros »

Those tags may not indicate differences in carbs, but perhaps year, or emissions systems codes. they do not appear to have any obvious correlation to physical differences to the carb it self. And, per forum member Xirdneh (who has likely rebuilt more old toyota carbs than anyone else on this forum) has found the main jet varies between 101 and 117 I think (though a few from Canada were reported to be at 99), and the secondary jets are usually 159 (being extra rich would make some sense since the secondary throttle and barrel is only engaged during hard full throttle acceleration).

I am in the middle of rebuilding my carburetor, it has 101 main jet, and 159 secondary jet. I have a box full of different stock carbs in varying conditions (and varying states of disassembly) from different year tercels I have accumulated (none are good for driving on right now, they all need rebuilding, so i use them for parts). I thought about pulling all the main jets out and comparing them for size, and try swapping them out in my daily driver every few weeks (it can be done without removing the carb nor taking it apart), to see how it affects my power and economy (with all that spare time I do not know what to do with...lol). it would be an interesting experiment, that might be acutally useful to the 2 dozen people on this forum keeping these old Tercels on the road with the factory carburetors. ;-)

The varying state's and changing year to year emissions requirements likely caused the difference in the main jets, and also in slight variations year to year in the vac routing and secondary emissions systems. it seems larger jets would produce more power, and smaller high economy, but with so many other changes in the systems, it is hard to know for sure. running extra lean could reduce the fuel economy, it is a complex relationship between efficiency, max power output, and emissions output. it is mostly a trial and error, back to back testing that would yield the best combination.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
hikersteve
Advanced Member
Posts: 55
Joined: Wed Nov 06, 2013 9:00 pm
My tercel:: 84 sr5 manual
Location: penn valley ca

Re: carb numbers

Post by hikersteve »

thanks for the insight guys.

is the FSM carb rebuild section pretty concise or is there any other steps or processes?
any tips are appreciated, thanks
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dlb
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My tercel:: none currently, 7 previous
Location: bc, canada

Re: carb numbers

Post by dlb »

hikersteve wrote: Sat Nov 26, 2022 8:56 am thanks for the insight guys.

is the FSM carb rebuild section pretty concise or is there any other steps or processes?
any tips are appreciated, thanks
The two times I have rebuilt Tercel carbs, I have just followed the steps that come in the carb rebuild kit. You basically just remove about 70 small things, clean some of them and replace some others, and then put it back together. First time doing it will probably take several hours.
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