I recently got an '83 truck that was built up and then stored since the mid 90's. After doing all the normal belts, hoses, etc., I want to tackle tuning the Mikuni 44's. The engine is a 22r with 10 to 1 pistons, cam, big valves and balanced and blueprinted. It is REAL rich through most of the RPM range. I do have an Innovate wide band to fine tune but would like a starting point for the various jets. They are a little too pricey to buy a bunch. Any idea's?

 

have you set the mixture screws on both carbs correctly according to the instructions first?

What about the fuel pressure regulator?

might want to read up on this. http://www.racetep.com/webjettune.html

I know it says weber but those mikunis should just about the same.

Probably not gonna get much help on here with the dual mikunis, as they are not that popular in the truck world. Maybe a celica forum?

 

thanks, I will try the car forums

 

I ran Mikunis on my 18RG truck race motor but now I run 45 DCOE Webers on my 22R race motor. First only use a return type regulator with a minimum size AN8 hose size or 1/2" tubing size tank return line. Do not exceed 2 to 2 1/2 PSI fuel pressure to the carbs period otherwise the carbs will flood. Your pilot jet size should be 45 or 50 (since you live in Florida) and turn the pilot jet adjusting screws all the way in till stop then back them out 2 3/4 to 3 turns out. Make sure your ignition total timing is set to 30-32 degrees advance with it all in about 2000 RPM. Use a carb sync gauge to sync your carbs. Set your idle to about 1100 RPM. Start the engine and wait until normal engine temperature is reached. Syn the carbs and let the engine idle. Use an optical pyrometer and adjust the pilot screws until each exhaust port temperature reading is within 30 degrees of each other. Use the sync gauge to check how close each carb throat reading is to each other; adjust each carb pilot screws until they are all really close. Take the vehicle out and drive it steady at 35 MPH for a good bit of time. Pull over, shut the motor off and check the spark plugs. See if the plugs all look about the same (Tan- Lt. Brown). Repeat this procedure until all plugs are about the same color, your Pyrometer temperature readings are about the same and your air fuel ratio reads about the same while driving 35 MPH. When all the above is okay adjust your idle to about 950 RPM. I do not know what your cam or engine modifications are but most likely the supplied choke tubes are okay. Whatever your main jets are, run your air jets about 30 to 40 sizes higher (150 main jet uses 190 air jet ). This should be a safe point to operate the motor until you can fine tune the carbs. Just make little adjustments and drive the vehicle fine tuning as you go.

 

Thanks for all the help!

 

I got it right on after a little experimenting. If anyone needs some jets, I have a several sizes.