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Which SU Needle?
Posted: Thu Aug 08, 2013 8:14 pm
by chris_bates
I have recently changed the 1098 engine in my pick up from one with a 940 head to one with a standard head. (The former engine needs a rebuild so the present set-up is temporary). The SU carb is a 1.5in HF4 fitted with an AAS needle. Although it runs sort of ok, the engine doesn't sound quite right and is jerky at certain revs.
What would be a more suitable needle?
Thanks
Chris
Re: Which SU Needle?
Posted: Thu Aug 08, 2013 9:17 pm
by chrisryder
I ran an AAA in mine with the same set up, with no problems.
Re: Which SU Needle?
Posted: Thu Aug 08, 2013 9:33 pm
by bmcecosse
AAA for a 940 head - but will be far too much fuel for a standard head. What carb is it - and what manifold?
Re: Which SU Needle?
Posted: Thu Aug 08, 2013 9:49 pm
by chrisryder
bmcecosse wrote:AAA for a 940 head - but will be far too much fuel for a standard head. What carb is it - and what manifold?
He's said it's a 940. And has also said it's a 1.5 inch HF4. Which I presume to be a HS4.
Re: Which SU Needle?
Posted: Thu Aug 08, 2013 9:56 pm
by bmcecosse
No -it WAS a 940 head, but NOW it's standard....and manifold etc???
Re: Which SU Needle?
Posted: Thu Aug 08, 2013 9:59 pm
by chrisryder
Oh, you're right. Still, I'm still running the AAA now I've gone back to a standard head. Possibly a little lean at high rpm though. Gets a bit warm above 70mph.
Re: Which SU Needle?
Posted: Thu Aug 08, 2013 10:35 pm
by bmcecosse
I doubt it is LEAN!
Re: Which SU Needle?
Posted: Mon Aug 12, 2013 4:55 pm
by chris_bates
Thanks for the replies.
The carb is an H
S4, (getting confused with HIFs

)
I'll try the AAA needle and see how I get on, although my run today did not seem to replicate the rough running problem so it may be the latest lot of petrol has now worked its way through the system ???
Thanks again.
Chris