Intro: This is my first attempt at rebuilding a carb.
While rebuilding my original 84 manual transmission carb, the air horn and main body were accidently damaged. I purchased an 85 MT carb on ebay for the parts. It looked OK with no apparent damage.

Primary issues from two tests:
Gas flowing into secondaries from top of main body.
Incorrect slight glass levels.

First test results:
Gas leaks at: Inlet bolts; fuel return fitting; air vent solenoid (maybe)
Gas flowing into secondaries from top of Main Body
Gasket between air horn and main body soaked with gas
Fuel in front bowl slightly high
No fuel showing in rear bowl (maybe too high or too low?)

Second test after fixing gas leaks at inlet:
Gas still in secondaries, not sure where it is coming from
Gasket between air horn and main body still soaked with gas
Fuel in rear bowl at line
No fuel showing in front bowl (maybe too high or too low)
Discovered air horn screws not fully seated and air cleaner bolt could be tighter
Tightened right-front air horn to main body screw and gas squeezed out

After the two tests (above) I took the carb back out and partially disassemble it to separate the air horn, main body and throttle body pieces.
With no gasket between the air horn and the main body, I tighten down the 7 air horn screws and the air cleaner bolt. Using feeler gauges I found a gap of 0.102mm along the right side between the air horn and the main body.

Suspecting a needle-float issue (incorrect slight glass readings on both tests) I removed the seats and compared the new (85) to the original (84). The 85 match the seats in the rebuild kits. The 84 seats have an additional appendage not listed in the parts catalog. (See image: 85 on left, original 84 or right.)

QUESTIONS before I resemble and test again:
Is the .102mm gap acceptable? Or is this the cause of the overflowing gas?
Are the appendages on the seats necessary?
What else am I missing?

Other stuff I noticed:
The only visible issue upon this disassembly was I had the gasket between the Main Body and the Throttle Body flipped front-to-back, therefore covering up one of the vacuum holes on the right side.

I removed all the jets and air bleeds from the top of the Main Body. One of the two primary slow air bleeds #2 had a blockage that I could blow out. The night before I installed the jets and air bleeds I verified all the holes were open. The blockage may have come from the not so clean screw driver either inserting or removing. They will be re-cleaned for the next test.

Also, I realized when taking this carb out of the car I failed to connect the electrical connection to the #2 MAB Solenoid after the initial rebuild.

Started to check the floats. The air horn was upside down for a day. I flipped it right side up to check the movement of the needles and gas came out of the front seat enough to coat the float. Nothing came out the rear seat.

Next test:
New air horn and main body gaskets.
Use seats, needles and floats from 84 carb.
Recheck air bleeds and jets
Tighten all screws and air cleaner bolt.
Connect all electrical components.

 

Use the old seats and needles unless there is real damage. The extra appendage is more filters which can be removed if you have a good fuel filter and newish rubber lines and such. They are extra protection against deteriorating rubber lines and any bits t hat get paste the main fuel filter. The inlet banjos also have filters. Also the 84 seats have bigger holes in them from looking at the pic, the 85 seats don't look the same..

 

Thanks.
The 85 seats match the ones in the rebuild kits and there have been previous warnings against using the needles and seats in the rebuild kits. I suspect the 85 has been rebuilt before. I'm sticking to the 84 pieces. My father had the 84 rebuilt twice before he gave it to me.

 

Make sure you can blow through the passage from the fuel line through to the seat location. I've seen these crust up on csrburetors that sat empty and the metal corroded.

There shouldn't be any gap, that's really weird. I wonder if the air horn is warped, assuming that you didn't get a float pivot lodged in there holding it up.
I used to run a modified Nikki with no screws, just the center bolt, so you shouldnt have leakage issues at all.

I've also never been able to adjust float height worth a damn, going by the official measurement, so I always just leave that alone if it was working right before. Given that you had to change the air horn this obviously isn't an option.
I'd check for restrictions and then set float height by trial and error, after you figure out why it isn't sitting right.

 

Good advice Peejay. I always set the floats by the window levels even though its a pain in the a$$.

 

The gap issue maybe a non-issue. When I measured the gap between the air horn and main body the gasket was removed. The air horn would rock front to back. After trying a 84 and 85 mix and match I discovered the air bleed (#47) on the bottom of the air horn was resting on the plug richer system (#93).
After removing #47 there was only a very tiny shift. With taking out #47 and the gasket, then inserting the center bolt and all 7 air horn screws, the only measurable gap was 0.076mm. I’m thinking the gasket can fill that in. Besides the feeler gauge, I use a 110 lum spot LED flashlight. Without the gasket in place there was a slight gap showing light going through, with the gasket in place no light entering the barrels. I even tried the light test with only the center bolt and none of the 7 screws, still no light coming through.

It may have been possible that one of the float pins was caught between the air horn and the main body for the first test. A third test will verify.

 

Is it possible to test the float adjustment without the engine running? Right now I have the throttle body, main body and air horn as separate units. I’m thinking I could stack them up on the spacer, connect the fuel lines then jumper the fuel pump as if I was testing the pump pressure and output. In-between tests I could take off the air horn, remove some of gas in the bowls with a large syringe, make an adjustment to the floats, then reattach the air horn. That way I would only need to fully assemble the carb and fully install once.

 

I guess you could but thats seems like more work than just removing the air horn to make the adjustment on the car and turning the key. Also, sometimes the carb doesn't sit exactly level in the car, so the floats actually adjust differently. I would also think what your suggesting would be messy and kind of dangerous with all the gas fumes falling to the floor. Make sure you are outdoors doing it.

 

Points taken.
Thank you.

After working with the parts I did see how it is possible to install partially assembled. Then jump the fuel pump to adjust the floats. This may also help confirm if the the initial flood over the top of the main body has bee resolved.




ut close enough that once I get the floats right I can complete the assembly.

 

No further leaks.
In the process of setting the float level. Working with a partiall assembled carb makes taking the air horn off and on is relatively quick.
This is where I'm at today. I'm thinking the rear needs about .5mm adjustment and the front not more than 1mm.

I started with the recommended 16mm + - .5mm but no fuel showed in the slight glasses.
Going up to 20mm after 6 seconds of the pump on, the levels were correct, but another 3 seconds and the levels were above the windows.
With the currentl setting of about 18mm I let the pump go 1 minute and the level stayed static as shown.

Thanks to

@peejay and @t_g_farrell for the assists.

 

Lookin good. Once you get them where you want them. Keep the pump running for a few minutes to make sure things settle at the right level. Then turn off everything and see if they leak down. If they leak down then you might be getting some siphoning affect from somewhere.

 

Current status:
I was very close but tried once more to get the front level up, and then it flooded. On the next test the rear would not stop filling.
I noticed the tabs on the floats and the top of the pins in the needles had deposits, so I cleaned them off. Not sure that helped.
I did not tighten the center bolt as tight as before, not sure if that changes the results.

I kept the pump on for 10 minutes and the levels did not change.
After 90 minutes with the pump off, the rear level dropped from the top of the notch to the bottom. The front remained the same height.

I did find after many trials that a change of .75mm moved the level 1/2 the height of the notch.
One or two more tests and I should have it.

I can no longer attach an image.

I measure using a digitl caliper. I set the target height, lock it and slide in. I gave up on the paper rulers that come with the kits.