'63 Big Twin low speed needle change?

[baytonemus]

I managed to find a "new" low speed needle for my 1963 Big Twin 40 carburetor. That part number according to my parts catalog is 308076. It came in an original OMC package but the shape of the tip is quite different from what was in my carb. The new one (on the bottom in both picture below) is much more blunt.



Did they change the shape of this or did I not receive the correct part? I'm sure it will still work but I would imagine that the range for fine tuning the mixture will be considerable smaller.

 

[bktheking]

Re: '63 Big Twin low speed needle change?

The bottom needle looks like a high speed needle from an earlier carb, 1960 maybe???? The top one looks more like a low speed needle than the bottom one, just my opinion. The range would actually be larger due to the longer tip, the high speed is less due to the shorter tip.

Part # is correct BTW.

 

[baytonemus]

Re: '63 Big Twin low speed needle change?

The bottom needle looks like a high speed needle from an earlier carb, 1960 maybe???? The top one looks more like a low speed needle than the bottom one, just my opinion. The range would actually be larger due to the longer tip, the high speed is less due to the shorter tip.

Part # is correct BTW.

Right, that's what I was saying. The bottom needle is the new one I bought and it would have a shorter range because of the blunt tip.

I wonder if there's any way I can find out what this is from. I can't find any numbers on these needles or the jets of this carb.

Thanks.

 

[bktheking]

Re: '63 Big Twin low speed needle change?

F_R??? He would probably know, why are you replacing is anyways, it looks fine???

 

[baytonemus]

Re: '63 Big Twin low speed needle change?

If you look closely you can see that it is a bit worn and the service manual says to replace it if that's the case. Maybe it's not worn enough to replace. I tend to try and replace anything that might need it when I'm rebuilding engine parts, especially on an older motor that I don't know anything about. It helps to eliminate possibilities when you have to start troubleshooting.

 

[bktheking]

Re: '63 Big Twin low speed needle change?

I'd use it , the wear is from rubbing against where it seats but it's very slight. Replace it if you want to , personal preference.

 

[baytonemus]

Re: '63 Big Twin low speed needle change?

Thanks for your input, bk.

 

[lindy46]

Re: '63 Big Twin low speed needle change?

Turn it in a drill or drill press and hit it with fine sand paper or a point file to smooth it out.

 

[baytonemus]

Re: '63 Big Twin low speed needle change?

Turn it in a drill or drill press and hit it with fine sand paper or a point file to smooth it out.

Isn't it just about impossible to do this in such a way that the point will end up perfectly centered? If you mess that up, it won't seat properly, will it?

 

[bktheking]

Re: '63 Big Twin low speed needle change?

Needles don't stay "seated", they are backed out to adjust for air flow, just take enough off to make it smooth again.

 

[lindy46]

Re: '63 Big Twin low speed needle change?

Isn't it just about impossible to do this in such a way that the point will end up perfectly centered? If you mess that up, it won't seat properly, will it?

Just be careful and only hit it lightly. I do it all the time and works for me without any problems.

 

[baytonemus]

Re: '63 Big Twin low speed needle change?

Needles don't stay "seated", they are backed out to adjust for air flow, just take enough off to make it smooth again.

Yes, I understand this, and I realize that I could actually use the new/different needle if I wanted to. In both cases, though, the carb adjustment instructions provided by the service manual would no longer be accurate and I don't really have much experience with outboard motors to draw upon. I'd probably need a little coaching on how to compensate for this.

Just be careful and only hit it lightly. I do it all the time and works for me without any problems.

I guess it wouldn't hurt to try it.