Morris Minor Owners Club

since having a water-heated manifold, bigger bore exhaust and carb from a metro turbo (with K&N filter) I seem to be experiencing a distinct pshhhht noise when I blip the throttle, along with a more worrying flat spot when accelerating, normally about half revs and most noticable in 4th where I seem to have lost a lot of low down torque too.
I mentioned it to a friend who immediately asked "have you got a K&N filter on there cos they're rubbish!" He suggested that it allows too much air in, and from all angles rather than the original filter which channelled it more efficiently into the carb.
Any thoughts?

p.s. I tried to change my profile name but it won't let me!!

"have you got a K&N filter on there cos they're rubbish!"

1st time I have heard that as they are recognised as the best and most free flowing filters on the market, and they do have a quite loud induction roar compared to the Moggie one and this is probably what you can hear, have you changed the jet since swapping the carb ? as I doubt the Metro Turbo one is anywhere near right for the standard Moggie engine and could be causing your problems.

well the guy at the garage that did the work assured me it was set up correctly and had the right jets. Would they cause the flat spots?

An incorrect needle can cause all sorts of problems. did the guy who did it actually change the needle ? I am no expert on the exact requirement Cam can usually suggest the suitable ones needed.

I'll find out the exact specification for the engine and carb, then post them here. Who's Cam by the way?

Thanks for all your help,

B

Who's Cam by the way?

He a regular poster who runs a slightly modified 2 Door and collects other assorted Moggies in differing conditions

I'm here!! Sorry I have not been posting much in the last few days but I have just moved jobs (200 miles north) and I have not got my own PC at work yet, or internet in my new house!!

Right well, if your 'mate' says: "have you got a K&N filter on there cos they're rubbish!" then tell him that you don't think David Vizard would share his point of view then if he asks who that is then smile and walk away..................

Could you give me the specs of your engine, carb (including what needle you already have), exhaust system etc and I can give you a guess at the needle you will need. Of course a rolling road session will get it perfect, but of you just want a quick fix then a tenner for a new needle might do!

Oh and having someone tell you that your carb has the 'right jets' is a bit worrying if you have an SU carb as it only has one jet and you don't change it, you just change the fuel metering needle that sits in the jet!! It's the Webber/Solex types that have different jets/emulsion tubes and you probably don't have one of those on. If you do, then I would swap it for an SU as they are easier to set up, more economical and comparible in producing power (if you use the correct SU).

Oh and Kevin, my modded Moggy is a 4-door!

well...I did a google search on David Vizard (I didn't know who he was!) and pages and pages came up on tuning just about every engine under the sun so I'm assuming he approves of K&Ns. I didn't take what my "mate" said as gospel immediately but when someone asks such a question immediately - an engineering technician at a university too - I had to wonder. I've since found a rolling road near Bristol and will hopefully be taking it there next week. I shall keep you all posted but thank you for all your help so far.
Cheers,
B

an engineering technician at a university too - I had to wonder.

Ah but what sort of engineering, does he actually know about combustion chambers and air flow volumes.
As you have found out David Vizard`s book is regarded as a bible when it comes to the `A` series engine as he has done more practical research than the manufactureres ever did with many before and after results including Air Filters, Manifolds, Carbs etc, if you are into a bit more performance his book is well worth reading even if it is a bit hard going at times.
Sorry about the lost 2 doors Cam

an engineering technician at a university too - I had to wonder.

Yes, I know what you mean! I'm a research associate at a university but I work in data communications/information theory - a bit different from mechanical engineering!!

That's why it's nice to have a hobby that's completely different from your work so you don't get bored with it!! The problem solving skills that you develop are applicable to pretty much anything though........

Sorry about the lost 2 doors Cam

That's quite OK Kevin It's probably because both our cars are Almond green and YOURS is a 2 door!

What engine to you have? if it is a 948 or 1098 the new manifold and bigger carb wont be happy, if you have a 1275 fitted you will need a new neddle for the carb to richen it up to match the increased airflow given by the k&n

K&N's are not crap , just and aquired taste, they tend to be very noisy and need the car rejetting or re needling to get the enigne to run properly.

turbominor would not run with a k&n unless 50% was taped over.. in the end i fitted a mg metro airbox and needle and it has same bhp as k&n with correct needle..

It's probably because both our cars are Almond green and YOURS is a 2 door!

That goodness I am forgiven still at least I would not mix our Travellers up as mine is Snowberry as I prefer different colours

OK well I still don't know the exact spec of the parts, but I can say it's a carb off a metro turbo, and the engine is a 1275.
A couple of things...can anyone tell me what the small piece of hose coming out of the back of the carb is? It doesn't go anywhere and I suspect it should go to the air filter? If I block it up it doesn't like it!!
I'm assuming the needle is the original metro one that matches the carb, now I thought of taping up half the air filter, you reckon this is worth trying?

I'm assuming the needle is the original metro one that matches the carb,

well the guy at the garage that did the work assured me it was set up correctly and had the right jets.

As you paid to have it fitted surely they are at fault and should correct the problem.

A couple of things...can anyone tell me what the small piece of hose coming out of the back of the carb is? It doesn't go anywhere

if that pipe is on the engine side of the throttle butterfly you need to block it off as the engine will sucking air and run lean..

you may need to reset the carb after blocking off



block off pipe 3, may be on other side of carb

That's why it is not running correctly.

When you block the pipe off the air is restriced and it will be running VERY rich as that's what you have set it to.

Block the pipe off and lean the mixture out a lot.