Another Carb Rebuild Thread

[77mustard40]

More info and more questions

OK I have ID'd the carb's manufacture date (5L24) as December 24, 1975, a Christmas Eve carb! Do any of the Guru's know if that carb is going to be an issue on a 8/77 truck?

On the stuck jet front I'm going straight into the dip and will try the AJAX Method after cleaning.

 

[edwjmcgrath]

Good luck, and wear gloves. That stuff is nasty. (The dip, not Ajax.)

 

[77mustard40]

Good luck, and wear gloves. That stuff is nasty. (The dip, not Ajax.)

Yep I picked up a box of gloves at the auto parts store. I've got the bowl on the boil so to speak so we will see tomorrow if I can get the jet out.

 

[77mustard40]

Got that jet out!

Good news, I ground down one of my larger screw drivers, applied Comet (sorry Ajax) applied some serious force and slowly turned and she came right out. You can see what great shape it was in.

Thanks for all the great suggestions. I'm sure I will be checking back when I start the rebuild. I've got the Keyster rebuild kit on the way. I will spend the next couple of evenings cleaning all the parts and pieces so I'm ready for when it comes

 

[subzali]

On a desmogged '77, you shouldn't have too many issues with fitting a '76 carb. You will want to connect the power valve (vacuum port at top front of air horn) to manifold vacuum - the gas filter just in front of the carb on the intake is a convenient location.

The '76 carb has a thermo sensor which you will not need to use.

You will have to hook up the vacuum port on the side of the carb to your distributor.

Good luck! Keep all those pieces accounted for!

 

[77mustard40]

On a desmogged '77, you shouldn't have too many issues with fitting a '76 carb. You will want to connect the power valve (vacuum port at top front of air horn) to manifold vacuum - the gas filter just in front of the carb on the intake is a convenient location.

OK so I'm making some progress getting all the carb parts cleaned up and waiting for BROWN to show with the rebuild kit. Took a minute tonight to investigate the vacuum source mentioned by subzali and this is what I've got. Suggestions?

While I've got you I'm going to pile on. Here are picks of an insulator I picked up with the carb / air cleaner package and you can see there is a problem. Am I ok with just breaking out the two part epoxy to re-install this vacuum port? Can I use this for my power valve vacuum source?

 

[subzali]

Looks like that gas filter is all jacked up. Next best bet, indeed, would be the vacuum port on the insulator base, if you can repair it.

 

[77mustard40]

Power Piston Retainer

OK I have finally received the rebuild kit and now have some time to start rebuilding and its only taken 3 steps to have my first question. Attached are three photos of the power piston installation.

1. as it was originally retained in the air horn when I broke it all down
2. as I just installed it after looking at and following the FSM (pic 3)

Was mine retained incorrectly when I broke it apart (with the flange of the power piston below the elevation of the air horn's base)? Have reinstalled correctly or was pic 1 correct and do I then need to rotate the retaining clip to depress the flange?

 

[Bennett]

subscribed

 

[77mustard40]

OK I have finally received the rebuild kit and now have some time to start rebuilding and its only taken 3 steps to have my first question. Attached are three photos of the power piston installation.

1. as it was originally retained in the air horn when I broke it all down
2. as I just installed it after looking at and following the FSM (pic 3)

Was mine retained incorrectly when I broke it apart (with the flange of the power piston below the elevation of the air horn's base)? Have reinstalled correctly or was pic 1 correct and do I then need to rotate the retaining clip to depress the flange?

Still need the power piston question above answered, any takers?

Also my kit came with 4 jets sized: 141, 150, 180, 220 - so I'm thinking two are high altitude and two are not. I live in Texas at roughly 650 feet above sea level so I don't need high altitude for this rebuild. The question is which is my primary and which is the secondary, the originals were too beat up coming out to read.

Just guessing it's 180 and 220. Close counts in horseshoes and hand grenades but I would like to be right about this. Help?

 

[77mustard40]

Still need the power piston question above answered, any takers?

Also my kit came with 4 jets sized: 141, 150, 180, 220 - so I'm thinking two are high altitude and two are not. I live in Texas at roughly 650 feet above sea level so I don't need high altitude for this rebuild. The question is which is my primary and which is the secondary, the originals were too beat up coming out to read.

Just guessing it's 180 and 220. Close counts in horseshoes and hand grenades but I would like to be right about this. Help?

After search for jets online I'm taking a mulligan and now guessing it's 150 primary and 220 secondary.

 

[edwjmcgrath]

For what it's worth, my 78 carb (NON US) had 153 and 180 jets in it. My spare jets are 141 and 180. And if you watch Pinhead's video, his were 124 and 230. And SOR has different numbers. Go figure.

I just put it back with the same jets, cleaned up, and it runs great.

 

[77mustard40]

Thanks, I think I'm going to start with 150 & 220. Save the 141 & 180 for the mountains.

 

[subzali]

My 12/78 carb has 1.36 and 1.71, which matches what SOR shows for '78 Fed carbs. Whatever you go with, check your plugs after a while and see if you're running rich or lean, and adjust from there.

 

[77mustard40]

My 12/78 carb has 1.36 and 1.71, which matches what SOR shows for '78 Fed carbs. Whatever you go with, check your plugs after a while and see if you're running rich or lean, and adjust from there.

Thanks for the input. Think I'll wait and see if Mark, Jim C or PinHead pipe in on the jet issue. I need to read and hunt parts more as the high altitude jets may actually be smaller than what came in the kit. I might need to go with the 141 and 180.

I looked back at the mangled jets that came out and I'm thinking they look like they approximate 180 and 220+ judging from the ID of each jet in comparison to he ID of the new ones. One observation is that the primary side of the carb was really black, almost like it was very rich.

 

[77mustard40]

It never ends!

OK I'm close to assembling parts (pending jet issue and power value install). It will have to happen next Sunday as I have a busy week with travel.

One more question, what's the rubber washer laying between the air horn and bowl (and in my hand) I don't want to start bolting together and find I missed something.

 

[bsevans]

What Kit did you order? The two K11-374A kits I just purchased have a 135 & 156 main jet and a 55 & 100 slow jet. The kit is for 08/76 to 07/80 Fj40s.

 

[77mustard40]

What Kit did you order? The two K11-374A kits I just purchased have a 135 & 156 main jet and a 55 & 100 slow jet. The kit is for 08/76 to 07/80 Fj40s.

Took your advice and ordered the Keyster K11-368A for 01/75-08/76. The carb I picked up was made 12/24/75. Don't recall the slow jet sizes but it came with 4 main jets.

 

[Bennett]

That rubber o-ring gasket looks like the gasket for the fuel window glass.
Is that new or old gasket?

I took my window out and cleaned and used the new o-ring that came with my kit.
fwiw

 

[Pin_Head]

Still need the power piston question above answered, any takers?

Yes, the retainer tab projects into the bowl and not the power piston.