My Weber DMTR is meant for a Golf 1.3, which means the throttle cable should pull from the front of car.

But a Polo throttle cable is too short for that.

I didn't fancy the cable-tie/jubillee-clip/rubber-grommet lashup which a Golf cable's end

is calling out for to mate with a Polo pedal box rod.

So, I drilled a hole in the bulkhead, bought a large cable grommet and fed the original Polo cable through that grommet in the new hole to pull towards the back of the car as before, operating on the throttle quadrant from the original Pierburg attached to the Weber and mounted the carb the wrong way round.

I've always wondered whether reverse-mounting a twin-choke downdraught carb could possibly have any efffects since the emulsified fuel has to turn a corner into the inlet manifold (and get past the hedgehog ) anyway before it's sucked into the engine cylinders.

The mixture has to get past the angled throttle plate, which if it were the right way round should direct the flow towards the engine slightly except at wide open throttle when it makes no difference. The mounting plate has a slight slope one end because the Weber holes are larger than the normal Pierburg holes (except on GK which has 26mm secondary I recall) which should direct fuel towards the engine slightly. I might even have pointed this to slope towards the engine, I'm not sure.

Over three years I've never observed any problems with the carb the wrong way round.

Until last week.

Well now I've learned that there is a right way round and a reason.

According to Passini the design is meant to have the float fulcrum pin towards the direction of travel.

Even though the floats sit centrally in each of the wells so it shouldn't matter - the wells should be in front of the jets, then as you accelerate or drive up hill (hard in east anglia) more petrol will cover the holes in the main jet emulsion tubes enriching the mixture a fraction.

Brake or drive downhill and less petrol covers the holes, weakening the mixture a fraction.

Brilliant.

So when with a reverse mounted carb your float needle valve has a tiny bit of dirt on it so it's not closing fully and you're only driving on light throttle the wells will overfill slightly. Brake as you reach an inevitable queue and the engine revs will rise.

Took me ages to work out why the revs were going up when I braked and my fuel consumption was down slightly (despite no more leaky fuel tank) and slow driving was still slighly jerky (despite a new bonded gearbox engine mount).

I thought it might be the manifold pressure drop from the brake servo making the Bosch Dignition unit retard the spark timing, but it didn't use to do that. Then again I considered an airleak from the brake servo diaphragm.

No it was simply dirt around the needle valve and the carb the wrong way round.

well observed, i was excited to read you had a servo, then the left hand driveness dawned on me :(

this float level business could explain as to why mine runs like a bag of crap when parked on a steep gradient.

Interesting,

I however didn't go for the reverse mounting method.Basically welded a plate onto the pedal with a hole to accept the 'male' golf cable. Annoying how certain golf and polo parts are the opposite or different.

i think welding a new bit on the pedal is the most sensible idea...that way a new cable is a easy fit

i chose to cut and weld the pedal ends of my cable to suit...which works fine

anyone got any pics of this pedal mod?

cheers

mack

I welded a plate onto the pedal to receive the golf cable but sorry I don't have a picture.

I basically cut off the male end of the pedal and welded the plate with the hole onto the cut end as well as a weld onto the other side of the curve.

I bought the golf cable first which helped me figure it out and made sure it aligned with the pedal from where it comes through the bulk head. Put the gromet from the polo cable into the hole on the plate.

Sorry it's confusing, I'll see if I can take a picture over the next few days..