Rebuilding the carburetor on a 20R

[Phares]

I have begun removing the carb on my 1980 pickup for a much needed rebuild. I watched Pinhead's videos on rebuilding an Aisin carb hoping to glean much needed knowledge although his is not from the same vehicle. I am armed with a rebuild kit from GP Sorenson, the FSM and the emission manual. Also, more belief in my skills than warranted and a whole lot of stupid. But with lots of pictures and the MUD community I'm sure it can be done. The baby started crying so I'm on pause right now. Currently I'm just in the removal, label everything take lots of pictures phase.

 

[Zack1978]

Best thread of the year!
I need to do this on my 79 4x4 short bed. On the Yota Tech website, the consensus is to order a rebuilt carb from National...$169.00.
Is your truck Federal or CA emissions?


Zack

 

[Phares]

Federal. It was originally purchased in NC. It's also only the third day of the year so I won't let that vote go to my head

 

[Phares]

Making progress. No need to drain coolant per the FSM.

 

[Phares]

Everything goes pretty well. The emissions manual is a huge help with labeling the vacuum lines. I've already found a couple that were broken so are destined to be replaced. The down pipe from the EGR valve to the intake manifold was split all the way around. Hopefully I can get a replacement. The air horn separated from the carb body without difficulty. All the internal Phillips screws are incredibly tight. Most of them I've ended up stripping and had to dremel in for a flat tip screwdriver. That does not make me happy.

 

[Phares]

The hardest thing so far is the interaction between the choke breaker which has a rubber diaphragm, the automatic choke, and the choke valve. The FSM steps you through removing the components but that requires removing the choke valve which is peened onto the shaft. I didn't want to do that but had to get the choke breaker off so that I could dunk everything into the chem dip. By partially removing the automatic choke you can remove the choke breaker. I reinstalled the auto choke and the air horn is currently dipping.

I did have to buy a 3/8" flat tip screwdriver to remove the seat of the needle valve. I've been taking lots of pictures and hand written notes. Things like the fact that 1 of the 7 screws connecting the air horn to the carb body is longer than the rest. The location of this one screw is important to note. It goes next to the fuel inlet line. So far I don't believe I've done anything irreversible.

 

[Zack1978]

If you want you can practice on your carb, and when you are an expert, I can send you my carb to rebuild.


Zack

 

[Phares]

If you want you can practice on your carb, and when you are an expert, I can send you my carb to rebuild. Zack

We'll see how this goes before I commit to anything but who can be sure.

 

[Phares]

Carb-on dating tells us: 9(Last digit of the decade) K(Letter corresponding to month) 22(Day of the Month). Therefore,November 22 1979. This corresponds perfectly with the trucks build date of November 1979. Almost exactly one year older than me.

 

[Phares]

Apparently while working yesterday I got a piece of metal in my eye. 500$ and a fair amount of pain later here I am. This puts the work on hold for a couple days until I heal up.

 

[Phares]

Went by the Toyota dealership today. They were able to order everything I needed but the EGR down pipe. Now I've got the old one soaking in the chem dip in hopes of being able to weld it back together. My eye feels much better today so work on the carb will restart on Thursday. Tomorrow is the princess' birthday so no garage work :-(.

 

[Phares]

Thank you GP Sorenson for not including the correct gasket in your kit... Oh bother.

 

[Phares]

Although they are pretty bad photos this is the carb body and flange piece. Both dirty.

 

[Phares]

Just some photos of the air horn, carb body, and the elusive thermostatic valve. The FSM says not to disassemble it so I have no idea what it does or how it works.

 

[Phares]

The air horn mated to the body, albeit without the gasket. The dealership was able to get me the gasket but for the California model, which I don't think is any different. We will see. It should be here by the end of the week. **turns out it was different...

 

[Phares]

This component is the automatic choke, which I thought was a pretty cool design. Coolant flows throughout the body of the piece. As the coolant warms up it flows over the gray ridges which heats up the metallic coil on the other side of the component. This causes the spring to uncoil due to the heat of expansion. The coil acts upon choke butterfly valve forcing it closed. At least, I'm pretty sure that is how it works. ***Ive decided I have no idea what it actually does...but all that thermal expansion mambo jumbo is correct. The choke butterfly opens up as the truck warms up though.

 

[Phares]

So we are all done with the carburetor! Everything went back together without issue. I had to cut the CA carburetor air horn to body gasket to fit but other than that hopefully it was done right. I have no indications the carb will not function. I am repairing the head of one flange to body bolt (Since toyota doesn't make them anymore) and then the carb can go back into the truck. That will happen tomorrow. So within 24 hours I should be able to report on the first function check of Jasmine. Here are some photos for you.

 

[Phares]

Reinstalled the carburetor tonight and after fuel made it into the bowl the truck fired right up. The idle was really high so I dialed that back down. I let the truck get warmed up and verified everything looked alright and gasoline wasn't going everywhere. Backed her out of the garage and drove her around the block. No issues! Tomorrow I'm going to finish replacing all the vacuum hoses and make sure everything is still ok. Then it is back to driving the old girl. I'm pretty happy. . Beer time.