OK, still working thru my carb rebuild, and I ran into an, uh, interesting component wear issue.

The linkage that operates the accelerator pump is worn about halfway thru:



And the bellcrank it connects to on the main throttle shaft is likewise very worn; the hole is worn to within a millimeter or so of wearing thru:



I have a spare carb that I can use for these parts, if I have to, and obviously replacing the linkage side of this is trivial.

The question is: what do I do about the bellcrank?

All the manuals say to never, ever, EVER disassemble the components on the throttle shaft. They don't say why, though. My assumption has always been that either the nut on the end is "staked," and will damage the threads when you take it off, or that the angle of rotation of all those parts is locked in place only by the nut, using some jig at the factory, and if you loosen it, you'll never get everything phased right again.

But that's just my guess.

The bellcrank I need to replace is the one closest to the throttle body, naturally, so that means the entire rest of that stack has to come apart.

QUESTIONS FOR THE NIKKI SENSEIs:

1) does anyone know for a fact why we're not supposed to disassemble the throttle shaft components?

2) is it possible for me to replace this part without forever bolluxing up my carb?

3) if 2) is no, then can anyone suggest a method of reinforcing or durably refilling the worn-away metal? Preferably, without resorting to brazing or welding,as I am not equipped for such, and many years our of practice, too.

Thanks for any help you can offer.

 

Find another carb at a pick in pull, this forum or ebay for 60$ and be happy you don't have to weld or braze?

 

1. Lots of springs, etc that are a huge PITA to get back on.
2. Yes, just be careful not to lose stuff. You can actually take off the stuff you dont need if you have removed emissions, cold & hot start assist, along with the cruise control. All that stuff hooks to that area.

 

On all my rebuilt/modded Nikkis, I only leave the throttle parts I need. Disassembling the linkages on the shaft isn't a big deal. Just make sure you pay attention to the order you remove them. I have never seen a accelerator pump linkage worn like that. Wierd.....

 

you could replace just the baseplate/shafts on the carb you have with a parts carb, but i have never had any problem taking everything off the shaft. Just do as bad83 said and pay special attention to how it all goes together.


isaac

 

I have a "spare" carb I pulled some years ago, but didn't realize until I had it home that is was a 79 NON-Cal manual... the only year built without power valves. Ports thru the baseplate are different. So, it's good for some parts, but not others. The crank piece & linkage I can use.

I just wanted to be sure I wasn't going to ruin the carb I need in the process. The warning in the Mazda Carb manual is very specific, but doesn't explain:

I hate warnings that don't explain WHY; makes me want to do that thing, just out of contrariness.

I can't explain the odd wear; none of the other links are worn to this degree. Must have gotten gritted up or something;

Does the same hold true for the throttle plates? I thought I'd read smewhere that the threads on the screws that hold them are "disturbed" after installation to prevent them from falling out.

If both can be safely removed, I may want to swap the throttle shaft with a newer one. Seems a lot of play in mine, & I don't want it leaking vacuum.