Carb decision - Rochester, Aisin, or Weber (1 Viewer)

[FJ55partsBoise]

Dave or Steve-

Do you have a wire from your carb leading to the coil? To make sure I am right is the coil the small thing that sits on the right fender up high? I think Steve told me this wire goes to the positive side of the coil. Right?

Also I have a loose wire down by the starter. There is a small thing that sits on the starter, almost looks like a mini starter. I noticed a loose black(ground?) wire that should be connected somewhere in that area? We have similar vintage trucks so I was wondering how your wiring is working as your truck appears to be 99.9% OEM.

Thanks

 

[IDave]

There should be 3 idle adjusting screws. The one on the passenger side, carb base (easy to find) is the idle mixture screw. The one that is on the firewall side, about midway down on the linkage, and the first one you see on that side is the fast idle adjust screw. Underneath THAT screw, on the firewall side, and kind of hidden beneath the linkage and behind and below the diaphragm is the idle speed adjusting screw. You have to approach it with a longer than normal screwdriver around the diaphragm from the driver's side. (You also approach the fast idle adjust from the driver's side.

If your choke cable (actually a wire) is hooked up, which I assume it is, the fast idle screw should not be touching it's seat when the choke knob is pushed all the way in. Otherwise, it will cause the engine to race at idle. (It is supposed to do that during warmup with the knob out, but then you push the knob in, and the tip of the screw no longer touches.)

You can then adjust the idle speed, engine warmed up, choke knob in, with the idle speed adjust screw.

Another thing that would cause your engine to race at idle is the situation where your accellerator cable (actually a braided wire with metal cylinders at the tips) is not set properly in it's mooring in either the attachment to the gas pedal, or in the cam on the carb. Either one is likely to effectively shorten the cable and send gas to the carb, resulting in a racing engine.

 

[IDave]

Trying to keep up!

The wire from the CARBORETOR magnetic switch or solenoid goes to the positive terminal on the coil, which is the same as the wire from the ignition switch and opposite the negative terminal, which has a wire to the side of the distributor.

My '71 coil is mounted to the cylinder head atop the engine block, but I believe your's is on the fender on the passenger side, as you said.

The picture below is of my starter. The STARTER magnetic switch or solenoid on top, (your "mini-starter"), has 3 wires attached on the front. (It also has a wire that goes to the starter motor itself). The top stud has a very large black cable coming from the positive terminal of the battery. A smaller gauge wire that is black and white striped comes from the ignition switch and attaches to a blade to the outside between the terminals. The lower terminal goes to the starter motor.

The big white wire attached to the top terminal in the photo is an accessory wire added by my PO; to what, I have not yet determined.

 

[FJ55partsBoise]

Dave- thanks for that again. it appears I have some ignition trouble also going on. This is in addition to vacuum trouble.

I'll update when I know more

Thanks

 

[FJ55partsBoise]

Carb decision - Aisin carb- over revs on startup

Update- I fixed the brake booster line this A.M. I also added the T to correct the vacuum line to the distributor. Now both lines on the carb T to a single line to the distributor.

It still revs up like crazy immediately on start up. It does this when the gas pedal is totally disconnected from the carb, using only the choke to get it running. I also adjusted each of the idle screws at different times and nothing changed each time. It still revs like crazy and fires up immediately. One good thing I think it will run well when I get this problem fixed as it runs clean and smooth with no shaking or knocking. The backfiring and blasting out the carb top has stopped also. Maybe the new base gasket as Dave and Steve suggested fixed the vacuum problem. It actually sounds good.

Where should I check next? Could it be the idle circuit cutoff solenoid or a clogged idle circuit that causes the over revving?, vacuum, electrical, timing. I really don't think it is timing as I have never ever touched or messed with the timing or the distributor cap etc.

 

[Poser]

The idle circut being clogged or a nonfunctioning idle solenoid, would cause the vehicle to not idle, not race.

If you open the choke back up, will it continue to idle fast, or does the rpm's drop?

 

[FJ55partsBoise]

When I bring the choke out and then back in there is no change in idle.

Still revs like a raped ape.

Thanks

 

[Poser]

I feel that there is something mechanically not correct on the linkage of the carb, not the truck that is creating this issue. Isolate the linkage, find all three adjusting screws as Dave suggested, make sure that the idle screw on the back of the carb that is difficult to get to as noted earlier, and make sure that it is not preventing the throttle plate from closing, and thus letting the idle speed drop. After verifying this, see what happens when you manually force the throttle to a return position, and if it affects the rpm's.

Good luck!

-Steve

 

[FJ55partsBoise]

I used a vacuum gage and checked for vacuum. No vacuum exists anywhere except the booster line. The fuel to air mixture does not work. This all tells me that this carb is shot. I plan on replacing this carb and using this for a core.

I plan on buying a completely rebuilt OEM Aisin carb for a 2F engine. I also want to get all of the original bracketry to the pedal. I am tired of messing with homeade setups that don't work right.

Thanks to everyone that offered their assistance and suggestions. Right now it runs well enough to get it on trailer to our new location. Once we are there I will put the rebuilt carb and correct brackets to hopefully solve this problem.

Where would you guys recommend buying a high quality Aisin carb and brackets? I don't want to mess with this system for a long while.

Aaron

 

[IDave]

1). Contact Jim Chenowith (FJ40Jim@aol.com) and see about him shipping you a rebuilt carb in exchange for yours, or rebuilding yours for you. You will do well with this option.

2). Order a rebuilt from SOR.

Jim and SOR are both likely to have the linkage you need as well.

 

[Herb]

I'm new at all this, so my suggestion is only based on what just worked for me. I was having similar issues with my F engine recently. I fiddled with settings till the cows came home, nothing improved or changed really. I have a weber 38.

Finally, I replaced my points with a pertronix ignitor and the problem went away. The truck drives like a dream. New points would have probably done the same thing, but that is not what I did. My engine wasn't getting a good, strong, consistent spark...so it ran like crap. Check your plugs, wires, cap, rotor and points.

I'll be interested to see how that pans out.

 

[rusmannx]

dissregard my original post #5. i have since traded in my old crap rochester for a new one (did it at autozone at $80) and i love it!
it fires right up, throttle response is super even when it's cold!
i had rebuilt my old rochester 3 times with no luck, but the replacement is working so good, i wish i would have done it 2 or 3 years ago.

 

[TEQ]

I would be most appreciative if the photos that were (apparently) originally in this thread were re-posted. My '78 has vacuum tubes going every which way, some are connected, some aren't. I need to see what it's supposed to look like...

 

[Corrugated Toy]

I have a '64 with a '69 1F. When I got her she had a single barrel rochester and everything else stock. I am nearing the end of my resto/mod with one difficulty. That is the "carburetion" problems listed in this thread. The mods are as follows:

Electronic Ignition
Headers
Rebuilt 2 Barrel Aisin (from SOR)
Removal of Oil Bath Air Cleaner

My girl is complete and in for a final inspection at my local mechanic.(I'll post all the pics when I get her back)

He is telling me that the carb is running very lean (as discussed earlier in this thread) and will not be able to be adjusted due to the removal of the Oil Bath air cleaner. I can understand that there may be a resistance change in going to a paper filter/snorkel, but I would think that could be adjusted. I am experiencing the same frustrations as the original poster, as this is the only issue holding up a 5 year total reso/mod. Any and all info. would be greatly appreciated.