Which Carb is correct for my 720 King Cab truck w CA Emissions?

[krggg]

I was hoping to replace the carb on my 1985 720 King Cab that has a CA emissions carb.  I had bought what I thought was the same refurbished original model Hitachi carb online.  It has the 6 lead plug, but has some differences.  The one I bought I believe has the altitude solenoid on it, the carb originally in my truck does not.  The auto clutch connection seems to be different too.  From what I had seen, I didn't think there were 2 different CA carbs for 720s, but maybe I'm wrong.  Does anyone know which is correct?  And can I use this carb and cap the altitude solenoid, (because it doesn't seem like there are any vacuum lines to connect to it),  or should I just try to find another carb?  Thanks!

 

 

 

 

[datzenmike]

Only an '85 California emissions carburetor will do.

 

There was a high altitude option but I think it was the same carburetor just extra hoses to a altitude compensator unit mounted on the right inner fender that would help lean out the mixture. (possibly this is not actually a California emissions carburetor for use at lower elevations in highly populated areas. My info says non California emissions high altitude) There were three additional hoses to the front right side of the carburetor. Just cap them.

 

What's the 'auto clutch'?

What's the altitude 'solenoid'?

[krggg]

Thanks for the response.  Should it still run okay if I cap the high altitude ports?  I think I saw another example on here of that.  Sorry for my ignorance of what things are called...I'm 100% new to working on a carb.  When I said auto clutch, I meant where the clutch cable connects to the carb, clutch valve?  Trying to get some pictures on here to explain.

 

[datzenmike]

I think the California emissions carburetor has the connections but they are capped and not used. Just like an optional tachometer. The wiring is all there just not used if the option not ordered. 

[krggg]

Thanks.  I realized there are two different ones.  One with the altitude compensator ports and one without.  The one with may have gone on the 4x4 models or the ST.  Not sure.

[720_Jeff]

Where did this carburetor come from?  If you have the original or what ever was on the truck, you can rebuild it yourself, or for ~$350 pay a shop to do it for you.  

 

We got at least two caburetor shops here in the LA area that lists the Hitachi as one they rebuild.  I'm sure there are plenty of others.  Should be a local shop or two that rebuilds in your area.

 

National Carburetor in FL sells rebuilt carburetors.  They charge a core.  They will also rebuild yours, after you send it in.

https://nationalcarburetors.com/carburetor-rebuild.html

 

Since your already into this for the carburetor you purchased, might want to keep at it and make it work, rather than just throw parts at it.

[Justin]

This should be a STICKY for DATTO NEWBS.

 

It's never ACTUALLY the carb,

Your timing chain has stretched.

 

Check your timing. 

(if it doesn't run- STATIC TIMING, 1st cyl @ TDC then,).

 

Has your truck SAT UN-DRIVEN for awhile????

CHAIN STRETCH is your dirty culprit.

 

Big-money Bet.

Edited April 7, 2023 by Justin

[krggg]

Jeff,

I can't rebuild the carb because the port that goes to the carbon canister has a hole completely through it.  They said they wouldn't even take it back for the core charge at National Carburetor in Florida. I did end up buying one from there...they are going to exchange the one I originally bought for the other, which doesn't have the to ports for the altitude compensator.  

[krggg]

Justin,

Was running okay, with some issues with jumping to high rpms at times, when it seemed like it shouldn't be.  I am mainly replacing the carb because it has a clear hole in one of the ports that I can't repair, and there has always been an issue with the clutch sticking since I got it. But also I'm new to this, so maybe there is an issue with that too.