Ok, im confused. Everywhere i look, including instructions that came with carb, says to get a SMALLER idle jet(primary). 3 calls to tech support i was told 3 times to get a LARGER primary idle jet.!!?? 1 suggested to advance timing more to see if that would bring up ROM to 750, it helped some.
1987 Toyota 22r, desmoged, no cat(replaced with turbo muffler to keep back pressure, so 2 mufflers). Engine rebuilt less than 5k miles ago. I rechecked/reset valves.
Advance is now set at 20 BTDC(No pinging at all but seems to have lost torque).
Lean/best done with no vacuum from ported line. Lean/best ends up at 1 1/2 out from bottom.
Problem starts there, idle is only at 400 RPM at this point, turning the idle screw to reach 750 RPM ( idle screw now at
1 3/4 from just touching) which causes 10 in of vacuum on ported vacuum, so i know my transition slots are exposed. I need to know if a smaller or larger primary idle jet will help raise the RPM WITHOUT having to turn the idle screw more than 1 to 1 1/2.
Jets in carb from LCE
Primary idle.....60
Sec idle............50
Prim main........140
Sec main..........140
Pri air correct...170
Sec air correct.160
Pump................50
I need to know because i only want to have to buy one kit, not both($100). 1 leans the carb, the other richens the carb.
everything runs good, just wanna get it closer to specs.
Thanks

 

Also, no vacuum leaks, fuel reg i installed to 2.5 lbs, all new ignition components. If i time it down to 10 BTDC it falls on its face. Running 93 non ethanol gas.

 

The 10 in vacuum is not enough to actuate the vacuum advance on the dizzy, but it shows the transition slots are open, techs said that port has to be at ZERO during idle. Anything over 1 turn past touching on the idle screw starts applying vacuum at the port. How can i raise RPM without turning the idle screw?? Seems to me the carb needs more air at idle. It will run with mix screw at 1 turn out, seems a little better at 1.5 out, chugs bad at 1 3/4 out. Sorry for the long post, just trying to get all the information out there. Also, not high altitude(central Ga).

 

No ideas?? Im Im thinking it is running rich since advancing timing helps. So i ordered a 50 and 55 primary idle jet. Will just throw them in and see what changes happen.

 

You should have much closer to 20” of vac with a stock engine and no vac leaks and correct timing. Low vac and idle suggests timing too late. Could there be a mismatch between your timing marks? I would quickly check tdc #1 and see if the marks are on target.

 

Maybe i wasnt clear enough, the 10in vacuum is when i have the truck running as best as i can, read thru the ported vacuum on the carb( the one that connects to the dizzy). This means my butterflies are open and it is running off both the idle jet AND the progression slots. I have not checked manifold vacuum yet, but it has strong vacuum. I assume over 20 in, but i will check that next. I included the 10in vac at ported carb vacuum to show my butterfly is open too much. With 0 vacuum at the ported carb slot, i cannot get the idle over 350-400 RPM. So, i am trying to figure out how to raise RPM closer to 750 with 0vac on ported slot(meaning butterflies closed over progression slots).
thanks

 

Also, when i adjusted the valves, i did recheck timing marks. Followed FSM and when i started truck it was dead on 0. I raised it up to 20 BTDC per redlines tech suggestion, and it DID raise the RPM(just not enough).
thanks again

 

Ok, i iolves the low idle issue. After days reading books and forums, this is MY understanding(not claiming to be an expert here, so just try and see if it works for you). The idle speed adjustment screw should not really be adjusted after setting. I found the secondary butterfly was completely closed, which starved the engine for air at idle, at lean best i couldn't get over 500 rpm unless i moved the idle screw too far and opened the progression port.
I removed the carb, held choke open with paper towel roll cut to length. Adjusted the secondary butterfly so that it barely covered the secondary progression port(had to go in 1/2 turn). Now i did the same with the primary, turned the idle screw in so that it barely covers the progression port. Then i reinstalled and never touched the idle speed screw again. Performed lean best and idle came out to 900. That small opening in the secondary butterfly increased the rpm at idle from 500 to 900. I did attempt to lower the rpm with the idle speed screw, BUT that made it bog ever so slightly when going WOT. Set the idle speed screw back to where I KNOW it barely cover the progression port, bog gone and idle back to 900. I am more than happy with it now. Gonna drive it a while and see if any other changes are needed.