Thread: how to set up SU carbies

The special tool you mean is probably the one you put down into the dashpot (the tube in the middle with the oil in it) which you use to adjust the depth of the tapered needle into the jet. I think it would be tricky to do this without that tool. I don't remember having any trouble getting hold of that tool years ago, so I'd be inclined to just get one. Remember to balance the carbies too.
Mine was running very rich at one time, and ended up being too worn to be able to lean it off enough. If you take the covers off and take the pistons out you may get some idea if the needles and jets are worn. They are easy enough to replace though.
Adam.

This is an excellent little publication -doesn't require lots of expensive tools...I've had a copyfor over 40 yrs!! and used it as a reference to tune the carbs on everything from a 1959 Morris minor to a cooper S, morris 1100, MGB etc and a 1956 Rolls (long gone) Lucas generators, starter motors, distributors and SU carbs were standard fare...
http://www.bmcno.org/manuals/Tuning%...rburetters.pdf

cheers

Are they actually SUs, (tall dashpot), or CD175 Strombergs/Solex, (short little dashpot)?

double post ...sorry!

Try http://www.bmcno.org/manuals/Tuning%...rburetters.pdf

this is an excellent little publication..

I've had a copy for "many" yrs and have used it as a reference for tuning all manner of British marques... no special tools needed -just steady hands, a good "ear" and a feeler gauge

That being said, if you can get access to one of those large scale DIY tuning tachometers (0-2000 rpm) which takes its pulse from the coil --all the better. A hand held vacuum gauge is also most useful...

Given that the engine is running well albeit a little rich, it may require just a fraction of a turn of the jet adjusting nut ...(see p 27 of the book)

good luck

I have a glass spark plug with a lead that connects to the spark plug lead, I used it for the twin 1-1/4 SU's I had on my minimoke. I fitted it to cylinder no.1 for the left hand carby and cylinder no.4 for the right hand carby. You remove the air filter and watch the colour of the spark, yellow for rich and blue for lean, adjust the mixture screw accordingly until it hovers between the two and then put the air filters back on to give a slightly rich mixture. Also have an airflow gauge to set the flow thru the air intake, take it for a drive and watch it go. Bought them 25 yrs ago from a mini nutjob and have been a great thing to use.
Cheers Ian

Gunson Colortune! Gunson | G4074 | Colortune Single Plug Kit

I got one from eBay UK. It's a great little tool. I think it's the 14mm that suits the Rover V8.

Originally Posted by Davo

Are they actually SUs, (tall dashpot), or CD175 Strombergs/Solex, (short little dashpot)?

They are 175 CD's but made by Zenith!
I just assumed all those style of carbs were SU's!

They don't appear to have the adjusting nuts on the bottom like SU's
I need to retitle this as "how to set up Zenith 175CD's?"

Anyone out there know how to weaken them a bit? I can't see anything other than the idle speed screws.
Thanks
Dave

Carburettor & EFI Service Co in Forge St Blacktown NSW, Have kits and toold off the shelf. I dropped off a pair of SU's only yesterday to be overhauled.