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MG Midget and Sprite Technical - Does one carb lead?

I was wondering if one carb speeds and slows things more than the other. It just seems that if I adjust the throttle screws on the rear carb on my 1500 it has less effect than if I adjust the front carb. Its always seemed like this since I started adjusting my carbs in the beginning. Its like the front carb leads.

Or is this indicative of something else?


Everything is going fine and I have started to use it daily again so this is just a wonder.

Thanks in advance, Dave
Dave Squire

Carbs not balanced?
Oggers

No in a perfect world all the cylinders will have exactly the same physical characteristics, the manifolds will be exactly the same and the carbs will be perfectly matched.

In reality one set of cylinders, carbs, manifolds will perform differently from the other.

In many cases that will not be noticeable. Not in your case!

Maybe do a compression test on all the cylinders and that may give a clue.


I assume the tappets have similar gaps, the plugs are new as are the plug leads.

On the other hand an inlet valve or exhaust valve not seating 100% will skew the results.
Eddie Cairns

Seems to do it when I am balancing them as well. Of course I could just be crap at it; but I have balanced a fair few times now (twice a year or more) as the seasons change.

Its not a great problem except when final adjusting tickover which seems a devil to get right.


Dave Squire

Ah, yes Eddie.

My number 2 has a lower compression than the other 3! Can't remember by how much but not enough to cause a major or any performance issue for a road car.

Number 2 was stuck when I inherited the car. Years ago now.

Amazing how one forgets these things when using the car every day.
Dave Squire

Yepp my front carb leads also... but i have a lower xompression in #3... but only by 3 psi

a little trick i found for a lean needle at the low rpm ...

use a 1/32 to 1/8 inch thick flat washer under the jet tube where it meets rhe adjusting nut...it moves rhe needle down the jet an step or two off the needle

seems odd ... as you would think the adjusting screw does that... i guessits an artifiacal way of adding a bit of chock to it

but i know exactly what you mean... just cant get a good balance...im guessing because i did my own porting work plus #3 being off lower by 3 psi
Prop and the Blackhole Midget

This thread was discussed on 12/10/2016

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