HItachi SU Rebuild Questions

[gav240z]

So I'm near the end of my Hitachi SU carb rebuild.

However I have a few outstanding questions:

1. N27 needles, are they still available? If so where? I butchered mine removing them. I have some SM needles, but they will be too big for the L24.

https://photos.app.goo.gl/TQmyxStyXKBJBqMz8

2. Butterfly plate fasteners. I damaged a couple removing them. Not sure if it's easy to order these or I need to speak to a machine shop etc..?

3. Loctite on threads? Anyone used it for say the fuel bowl bolt or fuel float breather etc..? I saw a white-ish residue on the threads when I removed them.

https://photos.app.goo.gl/sTGeN9f9Uu7zdvdz6

https://photos.app.goo.gl/NJU2BJZ5qxH8vNjU9

If anything I think the intake manifold threads need some kind of loctite to stop the bolt rotating when undoing/doing up the nuts to fasten the carb bodies to the intake. I know loctite comes in colours depending on how firm you want the lock. Just seeking recommendations.

https://photos.app.goo.gl/L8GNm5viQGhcKF7w6

4. Crush washers? And Fuel Filters I'm thinking Repco might have an assorted set you can buy?

https://photos.app.goo.gl/4SN3AkpseCfPLSgT9

Fuel filters that go on the fuel bowl inlet banjo bolt as a last resort filter.

https://photos.app.goo.gl/tjyNCLq8Ny9NqFNXA (middle of photo).

Does anyone know if this type of filter is readily available? I've kept the old ones incase someone tells me you have to clean the old ones and reuse...(I've re-used the floats already).

5. The Z-therapy rebuild kit comes with a plastic like o-ring (seen here).

https://photos.app.goo.gl/uKN5kyAR1dSYhhmL8

Still not sure what they are meant to be used for? Ideas?

*Edit these might be Banjo bolt seals (for fuel inlet), not sure I like these over OEM crush washers.

http://www.ztherapy.com/

Quote

Complete Tune Up Kit for 2 carbs (Needle & seats, SM, N27, N54, or N58 needles, ZT Nozzles, float gaskets, gas lines, banjo seals,4  insulator gaskets, Just SU's DVD)

I think the biggest cost in this Z-therapy rebuild kit is the ZT reconditioned Nozzles and Needles.

 

[gav240z]

Bookmarking for my own good.

http://www.sumidel.com/

Some rebuild kits come with the "crush washers" But the Z-therapy 1 didn't.

https://www.ebay.com.au/itm/Datsun-240Z-1970-73-Round-Top-Carb-Rebuild-Kit-Hitachi-SU-Carburetor-NEW-1077/223221946315

It cost enough that it should have IMHO.

[Aaron Neubauer]

Gav if its any comfort I have not used Loctite on any threads and have not had a problem.  

 

I am also not running the last chance filters in the banjo.  I’ve put a good quaility in line filter just upstream of the carbs instead as its far easier to inspect and maintain.

 

Any washers that tha ZT kit didn’t supply I recycled.  I made sure I had something between each steel fixture and the alloy.  I did the fitting for the fuel bowl up without anything and I was amazed at how soft that allow it.

 

The plastic O rings in the ZT kit are to locate and space the banjo in the sleeve.  I’ve installed them on my SUs.  When I didn’t I found the banjo bolt too loose after grounding out at the bottom of the thread.

 

According to an article on ZParts.com a standard SU needle for the 240Z is a BCE (https://zparts.com/index.php/resources/su-carburetors-explained/) .  Chucking that into Teglerizer’s finder shows it is similar to N27 but not exact.  I would think N27 needles would be available from a supplier in the states.  SUmidel may also be able to advise an equivilent, I found them very helpful and knowledgeable.

 

I dunno if that will help.

 

[gav240z]

16 hours ago, Neuby said:

Gav if its any comfort I have not used Loctite on any threads and have not had a problem.

Yes it does give some comfort, I may need to get loctite for the manifold studs anyway, so will use it sparingly.

16 hours ago, Neuby said:

I am also not running the last chance filters in the banjo.  I’ve put a good quaility in line filter just upstream of the carbs instead as its far easier to inspect and maintain.

I was thinking that also, but I may try clean up those last chance filters and shove them in, for that extra piece of mind.

16 hours ago, Neuby said:

Any washers that tha ZT kit didn’t supply I recycled.  I made sure I had something between each steel fixture and the alloy.  I did the fitting for the fuel bowl up without anything and I was amazed at how soft that allow it.

I have kept the older washers, so may just re-use them since they are the right size. Clean them up a bit etc..

16 hours ago, Neuby said:

The plastic O rings in the ZT kit are to locate and space the banjo in the sleeve.  I’ve installed them on my SUs.  When I didn’t I found the banjo bolt too loose after grounding out at the bottom of the thread.

I had Z-therapy rebuild 3 sets earlier in the year for me and I've still got 2 pairs. I can see they used them there, so will likely use them for that or try the washers depending on how tight it gets.

16 hours ago, Neuby said:

According to an article on ZParts.com a standard SU needle for the 240Z is a BCE (https://zparts.com/index.php/resources/su-carburetors-explained/) .  Chucking that into Teglerizer’s finder shows it is similar to N27 but not exact.  I would think N27 needles would be available from a supplier in the states.  SUmidel may also be able to advise an equivilent, I found them very helpful and knowledgeable.

Thanks for that, I see that Z-therpay have N27 needles listed also. So I can always ask them also. Shame I mangled mine getting them out! Should have been more patient.

I may have a few more questions about centering the needle with the nozzles (and the holder for the nozzle), along with setting floats etc..

I cleaned up and installed the pistons last night with springs etc.. the pistons didn't get vapour blasted. I may need to use some light sandpaper to smooth out the domes a bit, I noticed both pistons move freely, but every so often 1 side gets a little stuck.

So far the hardest part of their disassembly and rebuild is getting the right size washers in the right locations!

[1600dave]

42 minutes ago, gav240z said:

....... I may need to use some light sandpaper to smooth out the domes a bit,....

Hopefully not on the inside of the dome.......

They are a very close tolerance (rumour is piston and dome are a matched pair of selected tolerance items from the factory, at least for British SU's), personally I wouldn't touch either the piston or inner surface of the dashpot with anything coarser than very, very  fine steelwool or scotchbrite pad if absolutely neccessary

Edited November 29, 2018 by 1600dave

[gav240z]

Interesting, I think the Just SU's video supplied by Z-therapy shows light sanding to allow pistons to fall into bores evenly! I'll have to review it again, so far I've only scrubbed the piston with brake clean and a scotchbrite pad. I did notice that 1 piston seemed to fit and slide up / down better with 1 dome than the other. It's just as I say, 1 piston seems to get stuck half way down every so often (not every time). I will have a play with it during final assembly.

 

[Aaron Neubauer]

On 11/29/2018 at 3:17 PM, gav240z said:

Interesting, I think the Just SU's video supplied by Z-therapy shows light sanding to allow pistons to fall into bores evenly! I'll have to review it again, so far I've only scrubbed the piston with brake clean and a scotchbrite pad. I did notice that 1 piston seemed to fit and slide up / down better with 1 dome than the other. It's just as I say, 1 piston seems to get stuck half way down every so often (not every time). I will have a play with it during final assembly.

 

I don’t know if you are testing the piston with the needle.  I found a good verification method was to test fit the piston without the needle.  I found I had a teeny bit of sticking but was able to determine it was the needle/nozzle alignment not the piston and spring.

[gav240z]

Testing without the needles, but I'll have a play with it. Might take the plungers out of the dome as it might be creating some kind of weird vacuum/suction issue.