Having a bit of trouble with my mini. I recently swapped my twin su's for a weber 45dcoe and noticed the car started so much easier. But the weber was not tuned well for my engine and I'm not keen on driving it to get tuned as it is so rough. So I thought I would put my su's back on again for the drive over to the dyno. The problem is they have been sitting for two weeks and now I can't get the car to start.

They always were hard to get going and I have used start ya bastard before to get it to fire and then it would run fine. Now, it will start after using SYB but only for 2-3 seconds.

I can see fuel had made it to the filter so am thinking there is a blockage somewhere in the carbs. It was running ok before I pulled them off. Can someone explain how I should go about looking for the blockage? Any help is really appreciated.

Thanks for looking.
N

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"Beware the lollipop of mediocrity: lick it once and you'll suck forever" Brian Wilson

Have you checked the bowls to see if there is fuel in them ?

If the engine was hard to start beforehand , i would say it was more a choke issue , SU's like choke .

As for the SYB , you shouldn't need to resort to that stuff , something is not right, it is only running on that stuff for the 2-3 secs .

Where is the filter , just before the carbs ? Fuel can only run into the carbs until the needle & seats close off , so maybe take the tops off and blow them out with compressed air , seems strange that the carbs would start playing up after 2 weeks .

Good point! I never used the choke before. Ok, going to google fuel bowls now so I know what I'm looking for....

Did I mention I have no idea about carbs? He he he

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"Beware the lollipop of mediocrity: lick it once and you'll suck forever" Brian Wilson

http://1978mgmidget.com/manuals_and_booklets.html there is a su manual here

Or get the workshop manual in the how to on here

And is there oil down the damper

They would have to be one of the easiest carbs to work on , have you got a manual ?

With engine off , disconnect the fuel lines where they connect to the carbs , undo the 3 screws that hold the top on , and lift off , you will soon see if there is fuel in the bowl or not .
Whilst you have the top off , you can see whether there is any crap in the bowl or not , if so , soak the fuel up with some old rag and then clean out the bottom of the bowl .

To remove the float , needle & seat , pull the brass pin out that holds the float in place , then undo the seat with a spanner and remove the needle , blow out with compressed air .

Thanks for the info, I will give it a go.

Cheers!!

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"Beware the lollipop of mediocrity: lick it once and you'll suck forever" Brian Wilson

The other thing to check if changed carbs over .. is for manifold gasket leaks.
If not fully sealed will wreak havoc with mixture and can be too lean to run...
SYB may be enough to overcome this to get it running ....but not for long.... (like your description)
You may be able to hear a "hiss" if this is a cause will it is running....
(A case of been there - done that)

Yes if you have swapped manifolds you really should use a fresh gasket. The Su manifold and the weber manifold may press onto the gasket differently. Now you've gone back and forth you may now have a bad seal.

I would get a new gasket ready for when the weber goes back on. A good seal is important. An air leak here will burn valves.

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68 Morris Cooper S Mk1 (*ex 78 1275 LS 4th last built, 70 Morris 1500 OHC & 70 MiniMatic)

Thanks I have two manifold seals here, but didn't change the old one. I was hoping it would be ok for the 12klm drive to the dyno. I will change the manifold gasket wheni check the fuel bowls.

Thanks all for giving me some direction

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"Beware the lollipop of mediocrity: lick it once and you'll suck forever" Brian Wilson

I thought I should provide some closure on this. I took the tops off the fuel reservoirs and they had petrol in there. Soaked it up and they were clean inside. So I pulled the whole carbs off and noticed i hadn't tightened the nuts at the back of each carb- they were only finger tight. I meant to do them up but must've forgot. I also noticed that one of the brass washers and nuts was not fully tightened. Swapped the washer for one with a bit cut off the side and did them up tight.


All sorted and it is running. The funny thing is it was idling really high - up around 2500! Weird as I never touched the idle screws. Turned them down a bit and it seems fixed. Thanks for the advice and replies, it was very helpful and I'm stoked I fixed it myself.

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"Beware the lollipop of mediocrity: lick it once and you'll suck forever" Brian Wilson

Double post

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"Beware the lollipop of mediocrity: lick it once and you'll suck forever" Brian Wilson

Where are you going to dyno?

Just had my weber tuned at CNJ, almost doubled the power..

Is CNJ on kingston road at slacks creek?

I was planning on the closest place I could find that can find which is carbo tune at tweed heads.

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"Beware the lollipop of mediocrity: lick it once and you'll suck forever" Brian Wilson