Jump to content


Photo

Identify My carbs, i think HS6 SUs not Hitachi. Good, Bad, Indifferent?


  • Please log in to reply
43 replies to this topic

#21 1600dave

1600dave

    Senior Member

  • Members
  • PipPipPipPipPip
  • 591 posts
  • Location:Newcastle,NSW

Posted 29 December 2014 - 04:10 PM

Good to hear. You can see the difference between the needes in the graph below - BCM are much thicker, especially at the "fast" side of the scale (right hand side), meaning less "space" between the needle and the jet for fuel to get through.

Interestingly, I run (I think, should check again one day) BAX needles converted to suit "fixed" needle carbs on my overbored L18 (so around 1.9litre). But it is quite modified and I don't care for fuel consumption or low speed running (because race car).  These were chosen by a very good dyno guy with lots of MGB / SU carb experience, after I rebuilt them initially with BAZ needles from a recommendation by another guru with SU's on Datsuns.

Attached Thumbnails

  • 44014_84e9bc0b64a7932aeb13c423ff57ff862c17d67e.jpg


#22 WogsRus

WogsRus

    Advanced Member

  • Members
  • PipPipPip
  • 351 posts
  • Location:Hobart, Tasmania
  • Tagline:New Member

Posted 29 December 2014 - 04:14 PM

So far, and its only been a short spirited drive, the bax seam ok even at eve low speed.

#23 gav240z

gav240z

    Administrator

  • Administrators
  • 12,399 posts
  • Website:http://www.viczcar.com
  • Location:Sydney NSW
  • Tagline:Jack of all trades, master of none.

Posted 29 December 2014 - 09:00 PM

Does this needle swapping work for the Hitachi SU's also? I need to find out what needles are in mine, but I suspect my L28 is running out of fuel higher up in the rev range due to the L24 size needles in it and hence feeling flat.

#24 WogsRus

WogsRus

    Advanced Member

  • Members
  • PipPipPip
  • 351 posts
  • Location:Hobart, Tasmania
  • Tagline:New Member

Posted 30 December 2014 - 06:09 AM

Most certainly does, although U need needles with two precedes like sm or sh. Mine is a l28 with an early N88 head. Most people say that sm needles are to rich but you can lean them out just your idle will be a bit off. I have two seta of needels of a 260z but they are not stamped.

New needles are 14 each.

#25 gav240z

gav240z

    Administrator

  • Administrators
  • 12,399 posts
  • Website:http://www.viczcar.com
  • Location:Sydney NSW
  • Tagline:Jack of all trades, master of none.

Posted 30 December 2014 - 03:18 PM

Looks like I have a pair of "SR stamped needles" in my glove box. I think they came with the car many years ago. They seem to be unused and a quick Google search it looks like they might be the profile for a Jaguar XK140. Which is a 3.4 ltr motor. Probably would run too rich I'd assume.

#26 PB260Z

PB260Z

    Peter (PB)

  • Moderators
  • PipPipPipPipPipPipPip
  • 3,238 posts
  • Location:Northern Sydney
  • Tagline:Must stop buying new toys for the workshop.

Posted 30 December 2014 - 04:44 PM

Looks like I have a pair of "SR stamped needles" in my glove box. I think they came with the car many years ago. They seem to be unused and a quick Google search it looks like they might be the profile for a Jaguar XK140. Which is a 3.4 ltr motor. Probably would run too rich I'd assume.


They most likely would , but why not give them a try ?
It doesn't take long to fit them and costs you nothing.



#27 WogsRus

WogsRus

    Advanced Member

  • Members
  • PipPipPip
  • 351 posts
  • Location:Hobart, Tasmania
  • Tagline:New Member

Posted 30 December 2014 - 05:01 PM

go to here and have a look against SM needles which are a good base line start

https://www.google.c...jONW2aCgihXo7Kg


looking at is, the SR fall between SM and SH needles with leaner top end. Worth a try its only a 5 minute job.

Attached Files



#28 gav240z

gav240z

    Administrator

  • Administrators
  • 12,399 posts
  • Website:http://www.viczcar.com
  • Location:Sydney NSW
  • Tagline:Jack of all trades, master of none.

Posted 30 December 2014 - 06:36 PM

I guess the first thing to find out is what needles I have in the car currently. I was looking to buy this book.
http://www.amazon.co...s/dp/1845840739

SU Carburettor High-Performance Manual (SpeedPro Series) by Des Hammill

I was wondering if it was of any use? I have the ZTherapy DVD at home in Sydney but am currently in Melbourne and don't have access to it.

#29 WogsRus

WogsRus

    Advanced Member

  • Members
  • PipPipPip
  • 351 posts
  • Location:Hobart, Tasmania
  • Tagline:New Member

Posted 30 December 2014 - 07:11 PM

if you download the link i posted, it is software that allows you to see what needels you have. You dont really need to know what they are from more if they will work

#30 1600dave

1600dave

    Senior Member

  • Members
  • PipPipPipPipPip
  • 591 posts
  • Location:Newcastle,NSW

Posted 30 December 2014 - 10:00 PM

Hammill's book isn't bad, gives a reasonably simple explanation of how SU's work and what can be done to get them running right. Explains stuff like selecting / upgrading needles and modifying SU's for performance (ie racing).

#31 wildy55

wildy55

    Advanced Member

  • Members
  • PipPipPip
  • 422 posts
  • Location:Goldie

Posted 16 January 2015 - 12:36 PM

[quote author=Gav240z link=topic=15372.msg162432#msg162432 date=1419850854]
Does this needle swapping work for the Hitachi SU's also? I need to find out what needles are in mine, but I suspect my L28 is running out of fuel higher up in the rev range due to the L24 size needles in it and hence feeling flat.
[/hey gav/anybody
anyupdate on which needles to put in 240 hitachi carbs when theyre on an L28?
Just pulled mine out but needles have no id on them.
quote]

#32 WogsRus

WogsRus

    Advanced Member

  • Members
  • PipPipPip
  • 351 posts
  • Location:Hobart, Tasmania
  • Tagline:New Member

Posted 16 January 2015 - 01:32 PM

If needles have no id on them, they are hitachi carbs not SU.

SU needles will however fit in there.

#33 wildy55

wildy55

    Advanced Member

  • Members
  • PipPipPip
  • 422 posts
  • Location:Goldie

Posted 16 January 2015 - 01:56 PM

Yup, they're Hitacis alright. So are you saying that those BAX needles will fit and are the right upgrade on an L28?
If not, which are??

#34 WogsRus

WogsRus

    Advanced Member

  • Members
  • PipPipPip
  • 351 posts
  • Location:Hobart, Tasmania
  • Tagline:New Member

Posted 16 January 2015 - 02:54 PM

sorry.

For Datsun Hitachi carburettors, you need fixed needles, these have two letters on them, such as SM, SH etc.

For SU carburettors, you have two types of needles, swing and fixed. The swing needles use a small spring to apply pressure to one side of the jet, this was done for emissions and low throttle response.

All Hitachi carburettors, standard on datsun, have a fixed needle, so it fits in direct to the based of the piston.

From what i have researched and found, L28 running Hitachi, try SM or SH needles.

Use this tool to play around with

https://www.google.c...jONW2aCgihXo7Kg

#35 1600dave

1600dave

    Senior Member

  • Members
  • PipPipPipPipPip
  • 591 posts
  • Location:Newcastle,NSW

Posted 16 January 2015 - 03:55 PM

If you need to, you can run swing needles in a "fixed" needle type carb (ie hitachi carbs). The flange for the spring just presses off, you may possibly need to smooth some knurling on the needle that is under the flange so it will fit neatly into the piston. If so, whack it in a drill or lathe and carefully use wet & dry to smooth it down. Knurling doesn't hurt, but if it is raised a little, it can cause the needle to no longer fit in its hole.

#36 WogsRus

WogsRus

    Advanced Member

  • Members
  • PipPipPip
  • 351 posts
  • Location:Hobart, Tasmania
  • Tagline:New Member

Posted 30 January 2015 - 06:57 PM

WOP WOOP,just installed leaner needles, went from BAX to BCH. Much better top end pull so close to where it needs to be. Need to check AF on a dyno but my seat of your pants dyno says yessss.

#37 Clockwork

Clockwork

    Advanced Member

  • Members
  • PipPipPip
  • 63 posts
  • Location:Hobart, TAS
  • Tagline:Joel

Posted 26 April 2015 - 10:53 PM

Where are you getting needkes from WogsRus?

#38 WogsRus

WogsRus

    Advanced Member

  • Members
  • PipPipPip
  • 351 posts
  • Location:Hobart, Tasmania
  • Tagline:New Member

Posted 27 April 2015 - 12:43 PM

these guys

http://www.ebay.com....=item417daca456

near on over night postage and good pricing.



#39 Clockwork

Clockwork

    Advanced Member

  • Members
  • PipPipPip
  • 63 posts
  • Location:Hobart, TAS
  • Tagline:Joel

Posted 06 June 2015 - 02:08 PM

Humm,

I was just comparing your needle tests (SM, BAX, BCH) to the needles currently in my l26 - HS6's with BBK needles.

Im not totally sure what to make of the comparison, considering the differences in engines, however,

Mine start leaning out at about station 7, which is probably having a negative impact at higher revs.

I just replaced my sparks, which to my inexperienced eyes looks to be either quite normal or maybe a bit of high speed glazing (according to that picture scale in the haynes manual and posted on this site in colour).

This is the part that confuses me somewhat, as the car is running quite rich (smell and sound), yet seems to drop power at high accel, but the plugs dont appear to be burning overly hot (NGK BP6ES).

Who else has some SU HS6 Carbs on a stock l26, and what needles are you running?

I also cleaned my carbs up somewhat a few days ago, turns out my rear dashpot cover is a "front" cover (turned 90 degrees to make screw holes line up) - doesnt seem to be an issue as it doesnt really do much, unless it affects suction.  biggest issue I found is that my springs are different lengths, which is the reason my rear piston falls back more slowly (carby cleaner has fixed this somewhat though, it was sticking a bit).

Attached Thumbnails

  • 46444_c4f5f15239236726650302dd66b694797b1dea99.png


#40 WogsRus

WogsRus

    Advanced Member

  • Members
  • PipPipPip
  • 351 posts
  • Location:Hobart, Tasmania
  • Tagline:New Member

Posted 22 June 2015 - 09:15 PM

you will find that if you can smell fuel its likely to be lower rpm running, at high rpm its hard to tell mixtures. I have the old BAX i would be happy to send for you to test, i think they arnt best shape but wouldgive you a good indication. 




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users