thebrick

I just put the carb from a 87 22r on my 80 20r. It is a fairly tricky conversion. I used LC Engineerings mounting plate for the manifold to carb difference. They say you have to modify the manifold, but instead of dremeling out the manifold, i trimed the metal bits on the carb base plate instead and it fits fine.

There are two really tough parts are figuring out the vacuum lines, and modifying the choke. First, the vacuum lines. i had to use both vacuum diagrams to get it right. But be sure and plug the vacuum line comming out of the manifold just below the carb. If you don't the carb will run rough and rich. Second is the choke. I had to have a mechanic do this because i really didn't know how. They took the mechanical choke off the 20r and modified it to work with the 22r carb, ditching the newer electric choke on the 22r carb.

The truck runs and idles great. The problem is that when i am driving the rpms don't drop. If i am driving at any speed above 15mph and put the tranny in neutral (or push in the clutch) the rpms jump to 2500 rpm. I'mnot touching any pedals, no gas, just 2500rpm coast. When the speed drops below 10 mph the engine will idle normally. Has anyone ever seen this before?

A dealer mechanic suggested it might be the modified choke or the deceleration valce onthe newer carb. Any ideas? I'm stumped.

camo31_10.50

why didn't ya just keep the electric choke on there.....lol


just asking a question...seems kind of weird lol

Champ

x2...

thebrick

i would have if i could, but the 20r uses coolant temp to activate the mechanical choke. there is no hookup for an electrical one.

Champ

all it has to have is a 12v power source when the ignition is turned on. At least for the power source. not sure about any other changes. Check to make sure your linkage isnt binding up.

swampfox

could the throttle plate be hanging on the intake or spacer ?

thebrick

I have been looking around and you ar right, i can run the electric choke if i splice into a positive 12v and bypass the coolant lines for the old choke. I think i have some vacuum lines mixed up too. I'm wondering if the amount of vacuum matters? like maybe the AAP is getting too much vacuum, which is why it is running rich cold.

i the throttle plate might be sticking, but i cleaned the carb really well, and if the plate or linkage was sticking i dont know why it would always unstick at 10mph. Ugh, i should have just rebuilt the stock carb. I am going to fix the choke and try to check the vacuum lines and see how it is after that. Keep the suggestions flowing. Thanks guys.

80banana

I know this is a 5 yr old thread, but I came across it while reading about putting 22R carbs on 20R engines and was wondering if you figured it out?

To me, that sounds like what the 20R carb would do...once the speed sensor (in the speedometer) determined that you were over 10mph (or whatever the value was) it would energize a vacuum solenoid which would send vacuum to the throttle position diaphragm (forget the exact Toyota name). It's job is to keep the throttle slightly opened when you are moving over a certain speed and helps keep the engine from dying/bucking during deceleration or if you abruptly let off the gas while moving. It also helps the emissions a little while decelerating. On my car, I believe the A/C, through a seperate vacuum solenoid, also utilizes the same throttle position diaphragm to open the throttle slightly when the compressor comes on. It only opens the throttle very slightly, so you really shouldn't even notice it...if it's working and if it's adjusted properly. If the 22R carb uses a similar system, it sounds like your's might not be set right and may be pulling on the throttle too much while you're moving, but once you stop, it idles normally.

Again, was just reading through some old threads, didn't see a definitive resolution and figured I'd offer my 2 cents.

thebrick

I can't really remember, but I think i had my vacuum lines messed up. Anyway, I only ran that setup for 2 years before I put a 20r carb back on it. I was having trouble keeping it lean enough to pass smog.

The truck has been in storage for a while now due to my current apartment situation and because it won't idle anymore. Just dies when the engine isn't under load. I haven't had the time to mess with it in 9 months or so. Eventually I'll get it figured out...