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Correct needle for bog-stock 998?
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Author:  sgc [ Sun May 03, 2009 9:38 pm ]
Post subject:  Correct needle for bog-stock 998?
OK folks, quick question:

As above, what's the correct needle for the HS4 on a stock, late '70s high-compression 998?

This one I have has the emissions gear removed (naturally) and short 3-1 extractors into a 1-1/2" exhaust but is otherwise as Leyland intended.

It's running a floating ADF needle at the moment, but I have no idea if this is correct.. it certainly doesn't feel correct, it misses and farts and carries on above 3000rpm, but pulls like a train (ok, maybe a model train) when I yank on the choke.

I asked WinSU, but its needle selection logic is heavily biased towards UK-spec cars and I can't give it the bits that I have, so ADF isn't in its recommendations.. but then maybe it's not supposed to be.

Any suggestions?
Author:  850man [ Sun May 03, 2009 9:41 pm ]
Post subject: 
ADF is for a pollution 998 with an 1 1/2
ABX is for non pollution with 1 1/2. try this one.
Author:  simon k [ Sun May 03, 2009 11:21 pm ]
Post subject: 
vizard says Ac or M1, both of them are leaner than ADF and ABX

http://www.morrismini.com/SUNeedlesV2.a ... AC;ADF;M1;

thought about converting away from a floating needle, if you haven't looked at them, you might find the needle and jet are worn to buggery
Author:  sgc [ Sun May 03, 2009 11:25 pm ]
Post subject: 
simon k wrote:
both of them are leaner than ADF and ABX

http://www.morrismini.com/SUNeedlesV2.a ... AC;ADF;M1;

thought about converting away from a floating needle, if you haven't looked at them, you might find the needle and jet are worn to buggery


Leaner? I doubt that's what I need, choke makes it better! ;)

The needle and jet are basically brand new, I replaced them when I rebuilt the carb a few months ago. They were worn to buggery, the old needle looked more like a helix.. I will convert it to a fixed needle though, not a fan of the floating design -- I know how to centre the jet ;)
Author:  simon k [ Sun May 03, 2009 11:35 pm ]
Post subject: 
sgc wrote:
simon k wrote:
both of them are leaner than ADF and ABX

Leaner? I doubt that's what I need, choke makes it better! ;)



oops, I forgot to type what I was thinking that they mightn't be what you want... have you looked at the float level etc.?

even if you had a very lean needle in there, it shouldn't be missing and carrying on at over 3k rpm - the engine missing is usually an ignition problem

At the motorkhana yesterday there was a young guy with a clubman van, 998 and an 1.5" carb. It wasn't behaving at revs, so we fiddled around a bit, his leads were crap and tracking out everywhere, then one of the other guys had a spare set of used plugs, once they were in it was all good
Author:  sgc [ Sun May 03, 2009 11:40 pm ]
Post subject: 
simon k wrote:
even if you had a very lean needle in there, it shouldn't be missing and carrying on at over 3k rpm - the engine missing is usually an ignition problem ... one of the other guys had a spare set of used plugs, once they were in it was all good


If it didn't go so hard with the choke all the way on I'd be right there with you... but it's worth a shot, hell I've changed everything else 'cept the leads and plugs.

[edit]
simon k wrote:
have you looked at the float level etc.?


It's a fixed float type, but the needle and seat were replaced in the overhaul. Still, if this were the problem it wouldn't respond to the choke...

And yes, Mr. Colourtune suggests I have the idle mixture set correctly, as do the plugs.. although I do tend to run it on the rich side only because it misbehaves less.
Author:  BALLISTIC [ Mon May 04, 2009 7:12 am ]
Post subject: 
G'day sgc,

If the ADF (floating/spring loaded) needle is to lean I would try either AAL (rich) or AAM (richer) and if those dont do the job AAA (richest).
Then again I would put a fixed needle kit in it to reduce the wear on the jet tube. :wink:
Author:  sgc [ Mon May 04, 2009 8:34 am ]
Post subject: 
BALLISTIC wrote:
If the ADF (floating/spring loaded) needle is to lean I would try either AAL (rich) or AAM (richer) and if those dont do the job AAA (richest).
Then again I would put a fixed needle kit in it to reduce the wear on the jet tube. :wink:


Thanks Scott! Are these all exclusively floating needles, or are those profiles available in fixed needles too?
Author:  BALLISTIC [ Mon May 04, 2009 9:34 am ]
Post subject: 
Before you do any needle changes, have you checked the throttle shaft to see if its sucking air and leaning the fuel/air mix out.......sounds like it might be or it is sucking air from where it mounts to the manifold etc.....
If you want it checked out or a hand, give me a call and we'll sort out a time for you to lob around.

They are for floating needle pistons.

Something close in fixed AV or BE but i they would be way to rich for your application.
Normally for a stockish 998 with a fixed needle piston I'd normally use a DZ or DL needle. If it needed a richer needle something like a CP4, No.7 or AM.

Cheers Scott
Author:  sgc [ Mon May 04, 2009 10:39 am ]
Post subject: 
BALLISTIC wrote:
have you checked the throttle shaft to see if its sucking air


When I got it, this carb was in about the worst shape I've seen -- worn jet, squiggly needle and the thinnest most worn throttle shaft possible. Even the butterfly disc was worn.

That's all been rectified, it's idling like a champ and generally running OK with the exception of the slight misfire above 3k rpm under more than light throttle.

I do want to change to a fixed needle, but there's no rush in that department -- I want it to run properly first ;) Once I know what needle profile works, then I'll get the equivalent fixed needle and do the conversion.

Anyway, per Simon K's suggestion I swapped the plugs and leads for a known good set this morning and it made no difference. Aside from the dizzy cap they're the last components of the ignition system to receive attention, everything else is brand spanking.
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