Re-installing Carb. after rebuild

[78crzr]

I just got my carb. back from Jim C. after rebuilding and doing a few modifications, and I need to hook it up to a manifold vacuum source. MY FJ40 is the first vehicle I've owned with a carb., so I'm clueless in regards to where vacuum lines go, etc. I've hooked up everything the way it was before I removed for the rebuild, but I don't remember seeing anything hooked up to the manifold anywhere. The PO had it rigged in the worst way, most of which only made it run worse instead of better. At least I know I'm ignorant about carbs - guess he didn't. Can anyone tell me where to hook up the copper color part with the piece of masking tape on it? I'm told it needs to go to a vacuum source on the manifold. See pic below:

 

[78crzr]

Does it hook up to what looks like the head of a bolt with the black plastic cover on top pictured below? Cruiser is completely de-smogged btw.

 

[78crzr]

The only other place I can see that it might go is either right below where the carb. bolts to the manifold where there is a thin tube coming out with a black cover on it, or the thin tube coming out of the air cleaner housing directly above the front of the carb? It's tough to see in the picture but it is almost centered in the picture right below the body of the carb. Look for black plastic cover.

 

[78crzr]

Here's the air cleaner tube I was talking about. Hard to tell what emissions crap was piped to these fittings and what was for something else. ???

 

[spotcruiser]

???? What are you trying to hook up? Are you trying to connect the diaphram shown in the top photo? Is your rig stock? Has it been de-smogged? Is this carb original to your truck? Is this a Federal or CA engine?

 

[78crzr]

Trying to hook up the part in the 1st photo. It's the copper color part with the piece of masking tape on it. It is a '75 Aisin carb, desmogged, federal engine. Jim C. told me to hook it up to vacuum source on manifold.

 

[spotcruiser]

From the 1st photo, I'd say you are trying to hook up the throttle positioner diaphragm. It's part of your smog equipment. It is supposed to open the throttle slightly during deceleration (deceleration above 14 mph, closes during deceleration below 14 mph) to allow more complete combustion. The throttle positioner is normally connected to a port on your VSV. Do you have a VSV and all of the associated tubing?

From the 2nd photo, I assume your rig is de-smogged. The large hex headed device with the cap on it in the intake manifold is called a gas filter, and provides manifold vacuum to various smog gear. It's capped, so it seems that your rig is de-smogged.

I would guess that you don't need the throttle positioner hooked up if you are de-smogged and don't have to pass smog checks. Check with Jim Chenoweth about the need for the TP. If he says you should connect it to manifold vacuum, I guess that the gas filter in the intake manifold is a suitable place.

Just went out and looked at the carb Jim built for my '76. It's kind of a Frankencarb, so I don't know if this applies to your situation or if my throttle positioner is actually even functional. Jim hooked my throttle positioner up to that carb venturi port shown on your 4th photo (not the port on your air cleaner, but the port on the carb barrel just below it). Where is that carb port connected to right now?

 

[spotcruiser]

I'd say hook it up to the gas filter on the intake manifold and see how it works. That would certainly supply manifold vacuum. Send Jim an email verify the suitability of that port.

 

[Poser]

Run a piece of vac. tubing from the spot taped off, to the capped piece in pic.#2, and you will be good to go.

Good luck!

-Steve

(thanks for the pics, but they were so small on my e-mail browser that I could not see jack on them, and came back out here...)

 

[78crzr]

Steve,

I was just getting ready to call you, but noticed your reply. . I resized the pics before I sent them to you because I wasn't sure what kind of connection you had and didn't want to bog you down trying to upload them. Guess I went a little to small eh? Thanks for the recommendation here, I'll get it hooked up tomorrow. Can't wait to see what a good running carb. utilizing both barrels feels like.

Spotcruiser,

Thanks for the help as well. Being new to Cruisers and early model vehicles definitely creates a vertical learning curve.

 

[Pin_Head]

The vacuum line below the air cleaner in the last photo operates the "power valve", which is an auxiliary primary jet. It opens under acceleration and high power demand and it closes to lean out the mix under cruising situations for better economy and lower emissions.

I'm not sure, but I think that it is normally open when there is no vacuum on the line. It is normally run by the VSV and smog computer, but if these are gone, you need to choose either open or closed.

The throttle positioner in the first photo also prevents detonation or backfiring in the exhaust manifold during deceleration or shifting between gears. It needs a vacuum to drop the idle down to the normal levels. You could also just remove it.

My personal opinion is that it is better to just leave all of this engine control stuff on the engine and keep it working. It is not just smog related.

 

[78crzr]

Pin Head,

The PO removed all of the smog stuff before I bought it, and evidently put a '75 carb. on my '78 FJ40. At the same time, he did a total rig job on the carb. and had not accomplished anything in doing so. He had crap connected to one another that provided no vacuum whatsoever, and it was only running on 1 barrel. That's why I sent it to Jim C. to have it straightened out. Problem is, now that it is straightened out as much as possible, I don't know how to re-install becuase it obviously doesn't go back on the way it did when I took it out. I would have just left well enough alone if it still had all of the original equipment, etc.

 

[78crzr]

Took the 40 out this afternoon - woohoo! No more exhaust smell, and ran a hell of a lot smoother after with the carb. rebuild. Thanks again to everyone for the advice on the manifold vacuum source. Great to have her out of the garage running again!!

 

[xumFJ40]

TTT,

Sorry, don't have time to read, but will need the info in a day or to.

Sorry