Jump to content
Sign in to follow this  
WogsRus

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

Recommended Posts

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.

 

 

Share this post


Link to post
Share on other sites

Share this post


Link to post
Share on other sites

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.com/Carburettor-High-Performance-Manual-SpeedPro-Series/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.

Share this post


Link to post
Share on other sites

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

Share this post


Link to post
Share on other sites

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).

Share this post


Link to post
Share on other sites

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]

Share this post


Link to post
Share on other sites

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

 

SU needles will however fit in there.

Share this post


Link to post
Share on other sites

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.com.au/url?sa=t&rct=j&q=&esrc=s&source=web&cd=15&cad=rja&uact=8&ved=0CDEQFjAEOAo&url=http%3A%2F%2Fhome.comcast.net%2F~rhodes%2FPDF%2FSU_Needles.xls&ei=duOfVNb9DpO78gWbv4GIBg&usg=AFQjCNEsDxM5cLMEf1XbD66CgA7Dm98joA&sig2=qP1KgmDjONW2aCgihXo7Kg

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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.

Share this post


Link to post
Share on other sites

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).

post-11314-144023793709_thumb.png

Share this post


Link to post
Share on other sites

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. 

Share this post


Link to post
Share on other sites

ugh, just sent away for some BCH to test em out, accidentaly ordered BAX, but what turns up - BAW :S

 

BAW sit in between BBK and BCH so will stick em in anyway and have a feel.

Share this post


Link to post
Share on other sites

let us know how you went i wander why they stuffed up the order anyhow. 

 

I need to get mine to a dyno to see the fueling might need to lean it out at part throttle a bit

Share this post


Link to post
Share on other sites

Ah, one of my carbs looks like it needs a bit of rekitting, float definitely, started spurting fuel everywhere, couldn't seem to adjust fuel mixture to get it to stop. Noticed a couple of missing springs on one of the chokes to, and a couple of random bitsa screws instead of the real deal. Think I'll send em up to that guy in launnie to get a full work over.

 

Hate the idea of fuel falling directly onto a hot exhaust...

Share this post


Link to post
Share on other sites

cheaper to get a new set of carbs, the guys in lton are great but ridiculously expensive. I recently rebuilt my dads carbs with a full SU kit and it was only $180

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

×