Flat top SU float pin removal

[g9m3c]

Hmmm.... I can't tell from looking at an online photo of the float, or from your pictures exactly how the float sits on the pin. There is a small note on the bottom of the page EF-28 in the 1974 FSM that says "Note: The float and needle valve parts cannot be removed."

Since replacement floats are available, there must be some way of replacing them. I'm wondering if there is a possibility that the pin stays in place and the float comes off some other way, but by the look of the photos that would seem impossible without mangling the float beyond recognition. Otherwise I'd agree with geezer that it's got some wear groove, or it's slightly bent somewhere along its length. Does the pin wiggle back and forth at all?

I'm afraid I can't be of much more help beyond that, and these carbs aren't frequently dealt with.

Haha, I didn't notice that little note in my FSM before, but there it is! Like you said, I pulled up a replacement float for them on the computer at work(Advance Auto Parts), so there must be a way. I'll get it one way or another.

[geezer]

Yes, I've done rebuilds on dozens of carbs of all types. SUs are basically pretty simple and it's certainly your perogative to use flat tops if you want, even if most of us think they will cause you grief. I have followed your thread on HybridZ for the last four days and kinda wish I was there to help. The pin is likely set in place with an interference fit in the body. My best solution for removal would be to use a spring pin. If you don't know what that is they sometimes go by the name of expansion pin, roll pin, slotted pin, tension pin etc. I have hundreds of various ones in my parts bin. If you find the appropriate sized pin and force it onto the float pin, you will then be able to clamp some vise grips on the other end which will grasp the float pin tightly. Turn slowly & pull out.

[g9m3c]

Yes, I've done rebuilds on dozens of carbs of all types. SUs are basically pretty simple and it's certainly your perogative to use flat tops if you want, even if most of us think they will cause you grief. I have followed your thread on HybridZ for the last four days and kinda wish I was there to help. The pin is likely set in place with an interference fit in the body. My best solution for removal would be to use a spring pin. If you don't know what that is they sometimes go by the name of expansion pin, roll pin, slotted pin, tension pin etc. I have hundreds of various ones in my parts bin. If you find the appropriate sized pin and force it onto the float pin, you will then be able to clamp some vise grips on the other end which will grasp the float pin tightly. Turn slowly & pull out.

Thanks for the advice. I'm about to try your idea with the plastic tubing (the end of a pen I have). The pin's been sitting in carb cleaner for about 30 minutes now. If that doesn't work, I'm going to the hardware store tomorrow to buy a roll pin or two. I just get perturbed when people act like the round tops are the ONLY option for an inline, and anyone trying to make flat tops work is an idiot. Every thread I've read on every Z car forum I've been on that relates to flat top SU's gets the same response, "get some round tops." This engine will be in the car a maximum of 6 more months. Surely I can make the flat tops work for THAT long. After all, they worked for 31 years on this car. Again, thanks for the advice. Your advice is the best I've gotten on how to get these suckers out. I'll update with my progress.

Edited November 23, 2008 by g9m3c

[geezer]

In a worse case senario I would use a drop of yellow Locktight before pressing the spring pin onto the float pin and allow it to set. Good Luck

[g9m3c]

In a worse case senario I would use a drop of yellow Locktight before pressing the spring pin onto the float pin and allow it to set. Good Luck

Yellow locktight? I've only seen the blue and red around here. Red being the stronger of the two.

[geezer]

Yellow locktight? I've only seen the blue and red around here. Red being the stronger of the two.

I used to get the yellow from a machinist friend, but I just checked and don't have any more. It is much more potent than the red and actually deeply etches the surfaces of the adjoining parts creating what would be considered a permanent bond.

[g9m3c]

I used to get the yellow from a machinist friend, but I just checked and don't have any more. It is much more potent than the red and actually deeply etches the surfaces of the adjoining parts creating what would be considered a permanent bond.

Whoa, I need some of that. Haha, although, it might get me in trouble.

[g9m3c]

One picture says it all.

Thanks again geezer! I would have never figured out that little trick on my own. I won't forget it.

-Grant

[geezer]

Glad it worked. Don't buy any parts for these carbs until you have read the info I'm sending and you have determined which type you have.

[g9m3c]

I didn't really find anything definitive after tearing them apart. There was a small amount of debris in the needle and seat assembly, but not like I was expecting. The only passage blockage I found was this one.

It runs directly from the bowl up into the throat of the carb, right inside the choke butterfly. I'm not sure how critical it is, but I pushed some nasty black stuff out of it with a toothpick.

[RIP260Z]

g9mc3,

Coming late here, and I pleased you got the pin out. I have stripped a few sets of flat tops (as I am a fan) and to see how they can be stripped and how they work. The float pin on a pair of my flat tops came out just by pulling out, but another set I had to drill the blank side to expose the other end of the pin, then push it out. This was just for experiment, and if I was going to use it again, I would have just added a lead plug, which you find on these carbs, which are used to plug up the fuel galleries when the carb is drilled during manufacture.

Are planning to take the carbs more apart, as I maybe able to help? There are one or two other things you may want to consider checking (or you have already)

If you don't have the Nissan service manual that covers these, get it (and/or Nissan US service instructions for dealers), its a huge help (I am pretty sure this is where geezer got the pictures he put up from)

Regards

Ian