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Should be. Without oil in the slide the piston should drop quickly enough to make a kinda "tunk" sound, not an impact *THUD*... It means the piston to bore clearance is good. If it's slow with the damper out, it may be the needle isn't centered in the jet and rubbing onna way down.
 
could be because of that hardened line at the bottom again...
 
Nahh... they're hard to begin with.

They're part of the jet, and hard plastic.

(best "used car salesman Voice": "They're ALL like that, Sir!")
 
does it bolt right up to the ZS manifold? I want to see pics man!
 
Bolt pattern is the same, bore as well. The "trick" is gonna be fattenin' it to get a 13:1 across the range. Needles, babee, needles. Lots-a websites as info and support tho, so it should be "do-able" with a bit of research.

BTW: I have a SECOND one of those bad boys... BWUHAAHAAAAA!!!!
 
hmmmm... was just messin' around with "WinSU 2.1" and every needle it cam up with was described as "too lean". With the "best match" being 31% too lean in top end and 32% too lean in mid range.... there were other needles to choose from that were less lean in mid-range OR top end, but none of them were equally balanced like this one.... needle code shows as "R?" cause it's currently masked, cause I'm looking at the shareware version.
 
might be worth the $20 or so to find out. But isn't that program geared toward Spridget motors?
 
the latest version includes the 1800cc MGB motor, and tire sizes suitable for an MGB.

ermm... I just redid the engine configuration. Apparently I had "Fast road exhaust system" ticked off.... switched it to "standard" and the top choice needle came back as 28% too lean at top end and 29% too lean in mid range...

This might be "good" for emissions testing, but I dunno how it will be performance wise...

Someone a couple of months back did the ZS to a single HS6 conversion (the inspiration for my wanting to do it too) and seemed very pleased with the results... I may have to go search the forum to find out what needle he used.
 
here we go, Kenny. Here's the other feller that's done this conversion on this board. *with pics* of it installed, and some comments on the stuff he had to mod to make it fit better.

https://www.britishcarforum.com/ubbthread...true#Post139408

I need to read the thread thoroughly to see if he names the needle he used...
 
Now this may sound "funny" BUT:

We used to chuck an SU needle up in a drill, and with some *FINE* emery cloth or 600 grit wet-or-dry, selectively along the needle (starting with a known "lean" one), slowly go along and change the profile at the selected heights. It was "hit and miss" more than not, but now with access to a three gas analyzer... I'd be at it with micrometers and patience.
 
hmmm... I'm thinking I may have to do some of the same with a clamp and a drill to reach "optimum". I did find in the linked thread that the fellow use a DX needle, and was pleased with the performance. However, he had an ailing ZS that didn't allow his engine to get over 4500 RPMs. That problem I don't have, but 3rd and 4th gear acceloration leaves something to be desired in my car.
 
Just pulled it's mate apart, it's a ZH needle, .100"

I've the profile chart and needle charts. Google the "Tuning S.U. Carburetters" book pub'd by SpeedSport Motorbooks... If it can't be found any other way, I'll PDF the bloody thing! At least the pages concerning profiling the needles.
 
ah! yet another publication I need to purchase! I've already made plans to pick up a "Power Tuning S.U.s" book from the local auto books store...
 
a thought... since the Moss-n-ems are offerin' the HIF-44 in a ZS conversion kit... are the needles interchangeable between the HIF44 and the HS6? they use the same size jet...
 
Dunno. Never tried. Shank (shoulder) size and L.O.A. would be the only things really critical for interchange. A set of 0"-to-1" micrometers would be a good tool to have, IYSWIM. /ubbthreads/images/graemlins/wink.gif
 
oh, Doc, that WinSU proggy I mentioned earlier, has SU needles profiles of sorts... you can view the needle's "relative richness" in table form, and as a graph. It'll also allow you to compare needles on a line graph to see which ones should be richer, leaner, etc.

However, it seems to be a bit skimpy on documentation. For example, the ZH profile shows about 32% relative richness in top end and 0% relative richness at idle. I'm not entirely sure what that means. Does that mean it's 32% richer in top end relative to idle speed? -- scratch that... I've figured relative richness is richness relative to idle. The program uses idle richness as the base line.

on the other hand, When I look at the available needles that start with R (closest match suggestion) I find the needle with the highest "relative richness" is "RC". It shows 60% in top end. However, this needle (I assume it's this needle (RC)) is indicated as being 30% too lean on the "Needles to Try" screen. -- I read more of the program's documentation. It seems it bases fuel consumption on the power output of the engine, and uses the needle's profile to estmate the amount of fuel allowed into the mixture to create power. However, it makes an engine power assumption that I don't think is 100% accurate, and doesn't apply to *all* 1800cc MGB engines. From reading different the books I have, the power out put of the MGB engine varied with each revision. This program only lists 1 MGB engine.... for example, the program has all unmodified MGB engines with 70HP at the wheels, and 88HP at the flywheel...

hmmm... fun fun fun... need to do much more research-n-stuff...
 
Go into the chat software. Shed.
 
can't... gotta go home... not 'net there... /ubbthreads/images/graemlins/frown.gif

y'all have a good weekend
 
'k. You too.
 
did a bit of reading in the ole Naynes Weber/ZS/SU manual and found that it had "original applicatoin" list and a needle cross reference table. The application charts were nice enough to include engine displacements which enabled me to find engines of the same size hat utilized a single HS6 configuration. I've narrowed my selection down to about a handful of needles. The main applications of the single HS6 on a 1798cc engine was on 2 Leyland International trucks, several Morris Marinas, and a Wosleley (sp?). With the vast majority going to the Morris Marina, and most popular needle for the application being ZH (i think?... left my list at home and currently at ex-roomies place).

If I recall correctly, the Morris Marina had a similar single piece intake/exhaust manifold similar to the ZS equipped MGBs, but the intake (or was it the exhaust? ... Bret?) design was a slightly better design possibly allowing for better intake/exhaust flow.

I'll have to doule check n stuff...
 
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