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MG Midget and Sprite Technical - Over run valve on su disc

I’m servicing my SUs - AUD665 with plain jets

Yet the original throttle discs have the over run valve, the service kit is supplied with the plain discs.

Is it worth keeping the over run valve discs if they are not worn ? They can cause idle problems if worn apparently?
Or fit the plain discs?

C MADGE

My only experience is one came apart and ruined one cylinder. I would not keep them.
J Bubela

yes i agree they also impede airflow better to do without them. norman.
n speak

sorry i am troubled with afterthought i meant to say replacing the waxstat jets with standard type jets is a good move too. makes set up and tuning a lot easier. norman
n speak

Thanks for the replies. I have refurnished one carb so far, and used plain discs.
They were a big lump sticking up in the airflow!

C MADGE

Have the new spindle shafts taken out all/most of the wear play in the carbs ?
richard b

make sure you peen over the end of the screws on the butterfly so they can not vibrate loose, sorry afterthought again. its old age you know. norman
n speak

Richard - mostly. I’ll bring them over tomorrow, I would appreciate your opinion please.

Norman yes the screws have been gently spread at their ends to stop them coming undone.

If the throttle spindle play is ok i’ll Bend over the coming tab too.

Can anyone spot the assembly mistake in my photo of the carb? I rebuilt them one at a time copying the other to ensure it went back together correctly and I ended up copying his/her mistake! Never assume the person before did the job correctly, especially on my car!
C MADGE

Fuel bowel inlet pipe on wrong orientation?
Nigel Atkins

Breather hose inlet on incorrect side?

Mike
M Wood

Now I feel the need to check those suggestions in case they are wrongly assembled too!

C MADGE

Spindle back to front?

No, of course obvious now, the whole carb is vertical instead of horizontal.

Nigel Atkins

Disc is the wrong way round. Screws are on the wrong side of the shaft.
Alex G Matla

My photo is of the rear carb of the twin SU HS4 AUD665 setup

A standard setup should look like this (click on picture) http://www.minispares.com/product/Classic/C-AUD640.aspx


The linkage from the choke to the bottom of the jet is wrongly connected on mine. Its a 'C' shaped piece that screws onto the red plastic section at the bottom and attaches to an intermediate linkage to the sprung rotating choke cam. I was wondering why the linkage was a bit stiff. The correct way to fit is with the open side of the 'C' facing the plastic fitting. This way the linkage lines up properly and is smooth in operation.


I'll collect my anorak......




C MADGE

This thread was discussed between 13/04/2019 and 15/04/2019

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