Anyone know about SU Carbs?

[Robotstar5]

This is why you can buy inspection mirrors on a stick

Or beg, borrow, steal a small make-up mirror from the other half? a bit of careful pointing with a torch onto the mirror should be able to see inside the body.

 

[CKJDJK]

Check the throttle butterfly 8, some versions of SU carb had a little poppet valve in the butterfly (not shown) to allow a little extra air on over run to reduce pollution. If that is stuck open or leaking then the engine will race. These are often "repaired" by soldering closed. This type of SU was introduced fairly late on so if fitted to the Minor then it may not be the original carb.

 

[octo0072000]

if you take the dashpot off you should be able to see the throttle butterfly from the top without needing to get your big head
in the inner wing

 

[marfyboy]

arent su carbs oil dampered black cap on top of carb body filled with engine oil or it was on my mini

 

[octo0072000]

same type of carb 1/25 inch su

 

[KemppiFrog]

same type of carb 1/25 inch su

That would be 'inch and a quarter' in those days

 

[octo0072000]

That would be 'inch and a quarter' in those days

correct but 1/1/4in just doesn't seem look right on pc so i put 1.25

had plenty of them over the years on mini moggys midgets had a pair of
1/1/2s on a well modded mini 1275gt clubman mini and a marina 1.8TC

 

[Drains]

same type of carb 1/25 inch su

Didn't they use a dozen of those on this?

 

[octo0072000]

Didn't they use a dozen of those on this?

View attachment 28114

that's looks like fuel injection with the trumpets cant tell picture bit small nice model though

all you need to know about SU Carbs the original was based on a meat grinder
would you believe also pic of motorbike with what looks like a V 24 engine with 6 big SUs pic says 2 V12s looks like one crankcase wonder what MPG that did

http://www.sw-em.com/su_carbs.htm

 

[rtbcomp]

Somehow "Spong" carburettors doesn't have the same ring to it!

 

[KemppiFrog]

The original system was a leather bellows instead of a piston system. When the brothers were asked if it would hold up in use, they replied that they were in the shoe business, so knew a bit about leather.
Meanwhile....... What was the problem?

 

[tigler]

I have some SU manuals, what year is the Minor, or which version of SU is it, H2 or HS2 ?

 

[pedrobedro]

Somehow "Spong" carburettors doesn't have the same ring to it!

Well SU stands for Skinners Union so it might be butcher related but I never saw one with the winder handle attachment (probably a predecessor to the Metro turbo )

 

[M@tt]

well with a good clean up with some carb cleaner and a re-adjustment of the stops on the linkages we have one sweet running morris convertible again

the throttle plate was all gunked up and not closing properly and the throttle stop was also holding the butterfly open too wide on idle

so thanks for all the advice!! it resulted in a 12 pack of beers from a grateful neighbour, whoop whoop!!

to be honest i really enjoyed working on it so the beers were a bonus. Got to say i love the sound of these engines as well

 

[Chipper]

Nice one Matt

 

[Chickenjohn]

Good work matt! The A series engine is a brilliant little engine in the Morris Minor, sounds good, goes better than you would think, reliable and economical. Why would anyone change it??

BTW, another cause of a suddenly revving flat out Minor is the throttle return spring breaking or coming loose. This spring is usually attached to a nut on the exhaust manifold clamp, over time, the spring gets hot and cold and rusts and becomes weak, snaps and you get maximum throttle all the time!