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Carb spindle fuel leak

JonathanT

Not normal for Norfolk
Messages
1,201
Location
Wymondham Norfolk
#1
Hello everyone . Womble has suffered from an occasional drip of fuel from the throttle spindle/ shaft on the Zenith Carb straight onto the manifold. It only did this very occasionally. However it seems more prevalent now and definitely if parked on a slope nose up. Clearly dripping fuel onto a hot manifold is dangerous! This has prompted me to buy a new Carb I think from China. It seems very well made and an exact copy of Zenith 28if although the name is milled out. Upon inspection I can feel a tiny amount of play in the same butterfly spindle. I’m thinking will this new carb also be a problem? But I’m also thinking how on earth would my existing carb drip fuel from this location anyway???? My finger is pointing to the location of the drip ( although the photo is of the new carb yet to be fitted) I’m thinking it prob only occurs when I have stopped the engine and it’s something to do with expansion ? Any suggestion much appreciated
 

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#2
I have heard some horror stories regarding Chinese copies of carburettors and other precision made car parts, although these were on another classic car forum I inhabit. My advice would be to have your original carburettor refurbished, since that is an original part, which has worn over time. There's a company on Leighton Buzzard, in Bedfordshire I would recommend and geniuses in this area, whose details are on t'internet, but I can pass them on, if you PM me.
 

mr-reno-139

AKA Paul Cunningham
Messages
1,916
Location
lancing west sussex england
#4
modern petrol is designed for fuel injection cars and vaporizers at a lower temperature suggest maybe putting a thicker spacer block between the carburettor and the inlet manifold you may need longer studs to isolate the heat the float level 2 high causing this problem is also likely
 

JonathanT

Not normal for Norfolk
Messages
1,201
Location
Wymondham Norfolk
#5
modern petrol is designed for fuel injection cars and vaporizers at a lower temperature suggest maybe putting a thicker spacer block between the carburettor and the inlet manifold you may need longer studs to isolate the heat the float level 2 high causing this problem is also likely
Thank you Paul - I was sure I had read this somewhere before - probably from you .
 

JonathanT

Not normal for Norfolk
Messages
1,201
Location
Wymondham Norfolk
#6
It might be the float is to high and the chamber is overflowing.
I have heard some horror stories regarding Chinese copies of carburettors and other precision made car parts, although these were on another classic car forum I inhabit. My advice would be to have your original carburettor refurbished, since that is an original part, which has worn over time. There's a company on Leighton Buzzard, in Bedfordshire I would recommend and geniuses in this area, whose details are on t'internet, but I can pass them on, if you PM me.
Thank you Andrew.

Well I must admit I had read similar and it has to be said the same for the repro chrome bumpers. The reality fortunately is quite quite different. Yes the replica carb is slightly different HOWEVER!

I connected everything up and it fired up immediately and ran very sweetly. Far more even and steady than ever before. Quite how it fired up immediately I have no idea as the chamber must have been empty. I am very impressed with the performance now and visual inspection of the product Is every bit as good as the original. A direct replacement. It’s a shame the paper gasket and throttle cable tightening bolt were not included
 

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#8
Hi Jonathan

Mine was leaking from the same spot. You are right it only drips after a run when you turn the engine off. It took me ages to work out the source of the leak! If you release the nut securing the semi-circular throttle lever plate, having released the throttle cable, removed the return spring first and ensuring you make a note of the order of all the components which sit behind the throttle lever for refitting. You will come across a small circular rubber seal, if this is perished, fuel will leak onto the manifold. P70 in the Haynes manual shows the carb and the seal is listed as 17) bush. Please keep us posted as to how you fare with the Chinese carb long-term as I have been tempted in buying one myself.

Best Regards

Chris
 

JonathanT

Not normal for Norfolk
Messages
1,201
Location
Wymondham Norfolk
#9
Hi Jonathan

Mine was leaking from the same spot. You are right it only drips after a run when you turn the engine off. It took me ages to work out the source of the leak! If you release the nut securing the semi-circular throttle lever plate, having released the throttle cable, removed the return spring first and ensuring you make a note of the order of all the components which sit behind the throttle lever for refitting. You will come across a small circular rubber seal, if this is perished, fuel will leak onto the manifold. P70 in the Haynes manual shows the carb and the seal is listed as 17) bush. Please keep us posted as to how you fare with the Chinese carb long-term as I have been tempted in buying one myself.

Best Regards

Chris
Chris thank you that’s really interesting I wasn’t aware there was a rubber bush there. I don’t recall seeing one . I have to say I drove some distance last night and my goodness the drive is so completely different , not that it was bad before but it’s a whole lot smoother and responsive I’m very surprised as well as impressed.
 
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213
#10
Hi Jonathan

I am now tempted to buying one of the Chinese carbs. The bush is tucked away in a recess you can see it once everything has been taken off. Fortunately, I had a spare defunct carb and used the bush as a donor. I replaced it about a year ago and it has not leaked since.

Best Regards

Chris
 

mr-reno-139

AKA Paul Cunningham
Messages
1,916
Location
lancing west sussex england
#11
if you think about it there shouldn't be any fuel present at that point once engine switched off
so fuel there if unable to leak out will follow gravity and head down into inlet manifold instead
 

JonathanT

Not normal for Norfolk
Messages
1,201
Location
Wymondham Norfolk
#12
if you think about it there shouldn't be any fuel present at that point once engine switched off
so fuel there if unable to leak out will follow gravity and head down into inlet manifold instead
Paul I completely agree I don’t see why they should leak from that point although they could of course simply be DRIPPING from that point. There is a kind of breather on the top of the fuel chamber. I have seen fuel come out of there before when my needle valve wasn’t working g properly. So maybe it is an expansion thing. However that aside the massive general improvement in the drive of my car is well worth the change and much cheaper that reconditioning
 
Messages
107
Location
English but live in France 87250
#14
From where did you source the Chinese Zenith 28if copy from as you appear to have found a good manufactured copy, some I have seen are not so good.
 
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