1977 Asian carb problems

[gene6-22]

My stock liftback was getting 23 MPG and running rich. I could block open the choke on a cool morning and it ran good. I bought a used carb on ebay and it runs too lean while cruising (rough and bumpy). Full power is smooth and idle is smooth. Both carbs idle lean because I screw out the pilot screw many turns for best idle. Both have a new carb kits.The float level looks correct through the glass on both carbs. The level is on the dot in middle of glass. My book says float level is 5mm. Is that measured to the bottom rounded part of float? The lean one has a #117 main jet and the rich one, a #119 main jet. All other jets are the same. I will install the #119 in the lean-running carb and see what happens. I doubt that it will matter. I hate to mess up the stock looks by going to a Weber carb.

[rachuck21]

Hard to tell from here. Why not put carb number 1 on and adjust the choke?
Chuck

[73GTV]

Subject: 1977 Asian carb problems

My stock liftback was getting 23 MPG and running rich. I could block open the choke on a cool morning and it ran good. I bought a used carb on ebay and it runs too lean while cruising (rough and bumpy). Full power is smooth and idle is smooth. Both carbs idle lean because I screw out the pilot screw many turns for best idle. Both have a new carb kits.The float level looks correct through the glass on both carbs. The level is on the dot in middle of glass. My book says float level is 5mm. Is that measured to the bottom rounded part of float? The lean one has a #117 main jet and the rich one, a #119 main jet. All other jets are the same. I will install the #119 in the lean-running carb and see what happens. I doubt that it will matter. I hate to mess up the stock looks by going to a Weber carb.

see if any of these will help.
https://www.ebay.com/sch/m.html?_odkw=& ... r&_sacat=0


eBay item number:
263454375362

US $61.50

[gene6-22]

I had no luck moving parts from "rich" to "lean"carbs. Still cruises "bumpy". I need to revisit the "rich" carb and verify that it runs smooth. Maybe it does not, now. I suspected ignition problems but changed plugs and checked wires with an ohmmeter. Besides, if it is smooth at full throttle, doesn't that rule out the ignition system? What will cause a "bumpy" "rough" engine only during cruise? There is soot at the rear in the exhaust pipe, but could be from previously running the "rich" carb.
The float level is a wee bit high-at the top of the dot on the glass. When idling and hot, if I close the choke part-way, the engine runs slightly faster. Are Asain carbs that bad? Is that why so many people go to Webers?

[73GTV]

I had no luck moving parts from "rich" to "lean"carbs. Still cruises "bumpy". I need to revisit the "rich" carb and verify that it runs smooth. Maybe it does not, now. I suspected ignition problems but changed plugs and checked wires with an ohmmeter. Besides, if it is smooth at full throttle, doesn't that rule out the ignition system? What will cause a "bumpy" "rough" engine only during cruise? There is soot at the rear in the exhaust pipe, but could be from previously running the "rich" carb.
The float level is a wee bit high-at the top of the dot on the glass. When idling and hot, if I close the choke part-way, the engine runs slightly faster. Are Asain carbs that bad? Is that why so many people go to Webers?

Moving this moving that, Dude, just remove that old carb and clean and adjust it per the manual. If that doesn't work make sure your timing is correct so that you stand a better chance of discovering what is really wrong. Low compression, timing, clogged fuel filter, water in carb fuel bowl, etc etc...

[gene6-22]

I cleaned both carbs with cans of carb cleaner spray and checked for blocked passages. I disassembled both and did adjustments. The only adjustments are float level and idle screw. The float level is at the top of the dot on the glass. Both carbs idle too lean. (if I block 90% of air with my hand, engine speeds up slighty-the idle adjust screw is backed way out for maximum fuel) I cannot find replacement different jets. It also runs too lean during cruise. If I partially close the choke and stabilize it with a clothespin, it cruises smoother. I will try to check for an air leak at the intake manifold. Do you spray WD40 around suspected air leaks? I have replaced the plugs, set the timing, checked dwell, checked plug wires with an ohmmeter, looked at high-voltage wires while running motor in the dark,-no corona.
With wide open throttle, it runs great, which should rule out ignition as my problem.
A vacuum leak would explain a lot. Do I need a vacuum gauge to test it? What should it be while idling?

[73GTV]

I cleaned both carbs with cans of carb cleaner spray and checked for blocked passages. I disassembled both and did adjustments. The only adjustments are float level and idle screw. The float level is at the top of the dot on the glass. Both carbs idle too lean. (if I block 90% of air with my hand, engine speeds up slighty-the idle adjust screw is backed way out for maximum fuel) I cannot find replacement different jets. It also runs too lean during cruise. If I partially close the choke and stabilize it with a clothespin, it cruises smoother. I will try to check for an air leak at the intake manifold. Do you spray WD40 around suspected air leaks? I have replaced the plugs, set the timing, checked dwell, checked plug wires with an ohmmeter, looked at high-voltage wires while running motor in the dark,-no corona.
With wide open throttle, it runs great, which should rule out ignition as my problem.
A vacuum leak would explain a lot. Do I need a vacuum gauge to test it? What should it be while idling?

1977 is a 20R which I have never owned, Here are free PDF's which may help.
http://members.iinet.com.au/~stepho/manuals/Toyota/

My friend said to use "Vanish" to clean your passages if they are plugged or restricted. He said that "The Carb Shop" in L.A. uses that to clean their problem carbs. I know you already drained the float bowls to insure that the fuel is not floating on water. Good Luck.