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SU Carb Rebuild Questions


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#1 gav240z

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Posted 27 January 2015 - 07:28 PM

Hi Everyone,
So 1 thing I want to do is rebuild my SU carbs, I've been looking at the Ztherapy.com website and whilst I'd be happy to outsource to them, I'd rather not have to ship to the US and back and at the current currency conversion rate it will be rather expensive. Especially if the total is above $1000 AU which will then attract additional tax / GST etc..

So first things first.

1. Roller Bearing Throttle Shafts. So this seems to be a big selling point for them. I'll send them an email and ask if they would sell these separate and I can then get a competent local machinist to help modify the carb bodies to accept them.

Does anyone however want to hazard a guess as to what type of bearings these are and what size is used or where to get them locally?

Not a great picture but here is a view.
Posted Image

See here: http://www.spannerhe...n-carbs-return/

I'm guessing they are a 'needle roller bearing' but unsure, since I've heard they have a rubber dust shield also.

2. For the yellow zinc plating of throttle components I think the recommendation here for NSW was Alexandria Plating so I'll look into that. But if anyone has had any luck with DIY kits you can do at home please let me know?

3. I was also looking at the Ztherapy site which mentioned tumble polishing their carb bodies for consistent surfaces inside and out. I had a look and found this  video which seems to show this process on a set of wheels.
(Excuse the horrid music)

I guess I can ask the plating place about this. Worst case scenario and bench grinder / sand paper and lots of polishing compound will be the next best thing.

Edit: Or make my own from kitty litter and the wife/gf's kitchen bowls haha.


4. I'll probably still order Needles, Nozzles, Gaskets and Grose valves/jets (since they are a good idea)*

*Although maybe unavailable now.
http://www.classiczc...py-rebuild-kit/

Has anyone else rebuilt their SUs in this kind of detail before and if so any tips / advice or local suppliers you used?




#2 Cozza

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Posted 27 January 2015 - 11:28 PM

Hey Gav try Tim at Carburettor Service Company on Parramatta Road.
http://www.carburettorservice.com.au

BTW I love that DIY tumble polisher.

#3 1600dave

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Posted 28 January 2015 - 11:12 AM

I've rebuilt a few sets of SU's (although not to "concourse" standard).

Here goes :

1. Millions of SU carbs managed without needle roller bearings. I had a look on Ztheray's site, they use lots of exclamation marks whenever they mention "roller bearings" but I couldn't find where they state why they are needed ? They mention binding / air leaks / etc but simply getting them bushed or reaming and fitting an oversize throttle shaft should take care of these problems just as well as roller bearings ??

2. DIY kit is on my list of things to get, especially since there is a mob (Jane Plating Kits) about one suburb away from home. I get stuff done at the local plating place, its quite cheap, comes out nice. Only worry is them losing small stuff.

3. Last lot of carbs I did, I glass bead blasted them. Turned out very nice. The hydro blasting or whatever its called that Lurch has used on gearbox casings, etc, looks fantastic as well.

4. Grose valves - opinion seems varied on these. I've used them, and used the stock stuff. Never had an issue with either.

Suppliers - as mentioned CSC in Parramatta. Great service - I sent a pair of British SU bodies down to them, they re-bushed them and supplied new throttle shafts. I had them back in my hands about 3 days after posting them off, cost was something like $80. SUMidel also stock a big range of stuff for British SU's, not sure what they have for Hitachi's ?? I've always used genuine parts on Datsun SU's. But I haven't rebuilt any Hitachi's for many years now.

They really are about as basic as carbs get, very easy to rebuild. Here's my last pair :

Posted Image

#4 Enzo

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Posted 28 January 2015 - 01:25 PM

Hi Gav,
        I have just received my carbs (240z) back from James Flett at MIA Engines in Dee Why. I haven't put the engine back in yet as I am painting the engine bay in Por15. The carbs look and feel better than when I sent them over. James went right through them and gave them a clean bill of health. He initially found problems with the needles and binding.
David

#5 gav240z

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Posted 28 January 2015 - 02:54 PM

Just on the topic of Needle Bearings on throttle shafts.

http://www.mgexp.com...ad.php?1,516138
http://www.mgexp.com...ad.php?1,420453
http://www.mgexp.com...d.php?1,2259015
http://www.mgexp.com...d.php?1,1744311
http://www.mgexp.com...d.php?1,2572722

Seems to be a bit of debate about those roller bearings :).

Also found this page. https://thosbryant.w...ebuilding-hs-6/

Which has good info on Delrin bushings instead of brass.

#6 pauly_adams

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Posted 29 January 2015 - 10:23 AM

I have ball bearing runners on my shafts and slides on my Rolls Royce SU'S on my 260z, the difference in response from the jap SU'S to them is quite a bit, they are very very smooth also and have no signs of wear

#7 Riceburner

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Posted 29 January 2015 - 12:37 PM

I got spare roller bearings from SKF for my FCR's. All I needed was the diameter of the throttle shaft, the size and depth of the hole the bearing will sit in. I got them with a felt 'lip' edge to help stop any air leaks, the originals have this lip also, but the throttle shaft is in a much different spot compared to normal carbs.

#8 gav240z

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Posted 29 January 2015 - 01:58 PM

1. Millions of SU carbs managed without needle roller bearings. I had a look on Ztheray's site, they use lots of exclamation marks whenever they mention "roller bearings" but I couldn't find where they state why they are needed ? They mention binding / air leaks / etc but simply getting them bushed or reaming and fitting an oversize throttle shaft should take care of these problems just as well as roller bearings ??


Whilst I agree many SUs managed without them, they also had issues with throttle shaft wear. I do think the idea behind the ZTherapy fix is good and many owners or Ztherapy carbs report on improved throttle response due to the roller bearings. So I'm somewhat sold on the idea at this stage.

4. Grose valves - opinion seems varied on these. I've used them, and used the stock stuff. Never had an issue with either.


I can confirm these are NLA due to supplier issues.

Hi Gav,
        I have just received my carbs (240z) back from James Flett at MIA Engines in Dee Why. I haven't put the engine back in yet as I am painting the engine bay in Por15. The carbs look and feel better than when I sent them over. James went right through them and gave them a clean bill of health. He initially found problems with the needles and binding.
David


I may speak to James about it and see what he says on the topic. I don't mind spending a little extra to get the roller bearings done if I can find a suitable bearing. Not surprised but Ztherapy were reluctant to send me the bearings themselves. Happy to sell me everything else though.

I have ball bearing runners on my shafts and slides on my Rolls Royce SU'S on my 260z, the difference in response from the jap SU'S to them is quite a bit, they are very very smooth also and have no signs of wear


So you're saying the Rolls Royce SUs came with a roller bearing set up from factory?

I got spare roller bearings from SKF for my FCR's. All I needed was the diameter of the throttle shaft, the size and depth of the hole the bearing will sit in. I got them with a felt 'lip' edge to help stop any air leaks, the originals have this lip also, but the throttle shaft is in a much different spot compared to normal carbs.


Yeah I was thinking talking to a bearing distributor like SKF would be the way to go. The tricky part will be stopping air leaks and making sure the seal doesn't protrude into the butterfly of the carb or provide any interference.





#9 1600dave

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Posted 29 January 2015 - 02:28 PM

Whilst I agree many SUs managed without them, they also had issues with throttle shaft wear.


Probably a valid point. Although most were also daily driven for 10, 20, 30 years before wear started to become an issue.


I can confirm these are NLA due to supplier issues.


Damn. Should have stocked up.

So you're saying the Rolls Royce SUs came with a roller bearing set up from factory?

Throttle shaft, or suction chamber ? Some SU's had bearings in the suction chamber. I'm not aware of any with throttle shaft bearings as standard. Although I don't have Rols Royce SU's in my (sadly, quite large) collection of SU's

#10 Coops

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Posted 29 January 2015 - 03:21 PM

But if anyone has had any luck with DIY kits you can do at home please let me know?


Have zinc plated at home since 2011  .......  huge time sink!  Requires plenty of space and although weak acid involved best to have that part of the process away from cars and other precious items.

Also requires regular supplies of distilled water or similar.  I run a reverse osmosis setup for this purpose.

Main issue, and the time consuming part, is cleaning the parts in the first place.  Ultrasonic cleaner then buffed with wire brush is the process I use.  Any abrasive blasting produces poor plating - surface must be smooth and shiny as possible for best results.

If it wasn't for the fact that I have several vehicles being restored, that I have control over quality, I don't loose any parts and I can redo parts very easily when the finish degrades I wouldn't DIY and would just pay a good commercial plater.  The initial setup costs plus the cost of a regulated voltage power supplier gets quite a bit of professional plating done.



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#11 pauly_adams

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Posted 29 January 2015 - 10:38 PM

old school rolls carbs came with ball bearings not roller, the only way I knew they where rolls carbs is because I sent off some pics etc to a carb specialist as I was having trouble finding parts to fit, a good score at $200

#12 gav240z

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Posted 31 January 2015 - 11:05 PM

Ok so response from ZTherapy is that they won't sell the roller bearings separate. Fair enough...

Next question, I'm looking at their rebuild kit.
http://www.ztherapy...._price_list.htm

ZT150 which includes:

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)

This cost includes a $50 CORE CHARGE on your old nozzles.  Send back your old nozzles for $50 refund.


For the grand total of $180 + shipping. They will refund me $50 for the nozzles. So really it's $130 ish...(minus postage etc..)

However looking on eBay I saw this kit ~$40
http://www.ebay.com/...W-/221677486467

and this:
http://www.ebay.com/...W-/221674812528

It doesn't include all gaskets, nozzles, fuel lines so not sure how good it is? But it is a big price difference.

Anyway has anyone had experience with rebuild kits and if so what would you recommend?

I do like the Ztherapy stuff as I've seen the Just SU DVD and found it very useful and in part of the DVD they show another rebuild kit that doesn't seem like brilliant quality so happy to spend more if it means they work better than new.

#13 1600dave

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Posted 01 February 2015 - 09:26 AM

I'd go the Z therapy kit, just for the fact that you get new (reco'd ??) nozzles and fuel lines. The old fuel lines between the float chamber and nozzle can harden / crack, and nozzle can potentially wear if the jet wasn't correctly centred at some point in its life.

You get a choice of needle too, the other ones look like they will have the standard Datsun needles for an L24.

#14 gav240z

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Posted 01 February 2015 - 04:55 PM

Yeah that's what I was thinking also. Cheers mate.

#15 Zedstar

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Posted 14 February 2015 - 10:22 AM



Just fitted ZTherapy SU's as part of my 240 restoration. Tuned them this week , combined with head work Improvement is staggering. Strongly recommend installation.

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#16 gav240z

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Posted 14 February 2015 - 10:56 AM

Yeah I got my rebuild kit and now want to restore all fasteners and polish them up. They look great in your engine bay.

#17 brent012

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Posted 15 March 2015 - 11:56 AM

What needles should I be going for with a reasonably stock (afaik) L26? The guy I spoke to at Ztherapy reckons the SM needles could be dialed in and that they send them out to 95% of their customers, but from what i've read elsewhere they are very rich even on stock L28s. The n58s and the others are all l24 needles I think though?




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