J13 throttle return spring

[pidge]

I was sending a member some pics in the 520 section when I came across this ghetto fabbed up return spring. Sometime over its life someone used a gear clamp and some tie wire to attach the return spring. Top of the spring goes to the throttle lever which I assume is correct, but the bottom of the spring is Mcguivered on. I didn’t wanna hi jack buddy’s thread in the 520 section to ask my question, but anyone have a pic or drawing of the correct hook up points for the return spring?  Some pics of what I’m trying to explain. 

 

 

Edited July 20, 2023 by pidge

[pidge]

You can see the spring running down by the intake manifold and under that is where the tie wire and gear clamp to the exhaust manifold come into play. I looked around, but can’t come to a conclusion of where the bottom of the spring should mount. Any ideas?

-Pidge

[mainer311]

Everywhere I look, the Nikki carbs show a bracket on top that doubles as the throttle cable mount and the return spring mount. It looks like the throttle cable is supposed to pull from the top.

 

[mainer311]

Further, car parts manual shows the return spring attaching to a hole in the choke bracket, and the other end attaching to a lever arm coming off from the throttle cable cam:

 

[mainer311]

So, unless car parts manual is wrong, it seems like someone really made some changes on this truck. I know on my stock Hitachi carb (1971) the throttle cable pulled from the direction that you have shown. Maybe they swapped a later model carb on, or, just really turned it into a science project.

[pidge]

50 odd years you never know Mainer311 someone might have swapped something on. I wouldn’t know what from what would swap on there and work. I’ll have a look again vs. your pic and carb model you sent. Thanks again, I’ll see what I can come up with. As for now it seems to work fine knock on wood. 
-Pidge

[hucklefish]

pidge, thanks for starting this thread, it's very helpful, and also for answering my questions in my thread.

I labeled mainer311's picture with what I think are the right numbers from car parts manual:

I think you and I are both missing #26, and we both have the version of #92 shown in car parts manual instead of the version shown in mainer311's picture that has the choke lever on bottom of the plate.

With what's left of today I'm going to be fabricating a new bottom bracket for my alternator, so I'll try designing a throttle cable bracket while I'm at it. Also, in my case, the choke cable and throttle cable both come at the carburetor from the wrong direction, so I'll have to find longer versions of them as well.

[hucklefish]

pidge, while looking again at your pictures in my thread, I realized that you actually do have a version of #26, but it mounts under the screw #23 on the driver side rear corner instead of the one I highlighted above, and your throttle lever #9 is just rotated  about 150 degrees ccw from what's shown in the diagram above, or maybe upside down. That's probably why your throttle return spring is in a goofy location, because the way your cable comes in, if the spring was where mainer311 says it should be, the spring and cable would be right in each others way.

Does the end of your throttle shaft have a flattened cross section that's roughly horizontal when the throttle is closed? You'd be able to see it when looking at the nut that holds the throttle lever. If so, a simple laser cut plate could mount under that nut and give you a place to attach a spring that pulls back to the bracket  the throttle cable is attached to.

Here are a couple marked up screenshots to show what I'm talking about:

 

[hucklefish]

Here's the new part I'm talking about:

It might still work even though it looks like your throttle shaft end doesn't have those flats on it. It kind of looks like you have a plain washer between the nut and the throttle lever, and a small alignment hole in the throttle lever.

Take out this washer:

Replace it with a cut and bent plate that looks like this, with a little hook into that small hole to keep it from spinning on the shaft, then attach the spring to pull in the direction of the arrow, maybe to your throttle cable bracket:

[pidge]

I’ll have a look tomorrow when I get in. And try and compare it. Thanks man. 
-Pidge

[hucklefish]

@pidge, I've made two custom parts orders from sendcutsend.com, and I wrote up my design process and the experience with sendcutsend in two posts, which I'll link to at the bottom of this one. I also designed a little throttle return plate to go on your throttle lever like I described above, and I was going to include it in one of my orders and just mail it to you, but I forgot. I think I can probably attach the dxf file to this post as an attachment, and you could upload it to sendcutsend and order it yourself if you're interested. Or you could probably make one yourself with a hacksaw and drill and save some money, so I'll also attach a PDF that you could print out and use as a template - notes on that below the screenshot. It's designed based on my throttle lever, so I don't know for sure that it would fit your throttle lever, but I think yours is the same as mine except rotated about 90° ccw.

Here's a screenshot, with some notes to explain:

 

You could probably make the bend in a vise with a drill bit and some kind of V-block. The PDF has dimensions, and I highlighted the only ones I think are critical - the rest are just suggestions. I'm not sure how you'd make the pin by hand - maybe in a shop press if you could drill a hole the right size in a piece of fairly hard steel and put a tiny button of weld on another piece of steel to make a pair of punch press dies. Or the male die could also be a bit sawn off the end of a grade 8 bolt and epoxied to the top block.

 

My post on making a carburetor throttle cable bracket using sendcutsend:

My post on making an alternator bracket using sendcutsend:

 

SCS-throttle-lever-return-01.dxf

[pidge]

Thank you my man. After swapping plugs, gunning carb cleaner, cleaning points and inside the dizzy my baby is running smoothly again. I’m not hiding my breath though.