What might help track the noise down is a 2-3 ft length of garden hose or similar used as a stethoscope. Quicker than trial and error dismantling.
Sounds coming from the right carb in time with engine. Tightened 4 screws and retaining bolts. Can’t figure it out as no mechanical parts in carb?? Any suggestions? Cheers Sent from my iPhone using Tapatalk
Haha, so it was the carb. Did you have a listen around the spindles? An air leak can sound mechanical, and that sounds exactly like my Bug. According to the reconditioner who I paid good money to Weber's can whistle at the spindles, especially the Italian ones apparently. Tho' my carbs aren't the same as yours and I am not certain what I will do but it's a winter problem as it's running fine, it seems to leak out, not in.
The spindles turn the butterfly valves, or perhaps more obviously, they are the pivots that open the throttles when you hit the gas
Should be, could be...can be tricky. There is one each side of the manifold, 13mm spanner, maybe 12mm as they are sometimes used as it's tight. Google some photos and you'll see. If you squirt carb cleaner at this joint and the engine note or that noise changes its leaking. Gasket can act like the reed in a sax.
If the carb body is worn where the spindle passes thru it, then the seal is lost. The engine is really just a big air pump, so its not surprising that air will find any small gap. I am not familiar with your carbs but on mine the spindle exits and reenters the carb between the two barrels; that's where the whistle or chuff is loudest.
Oh it's quite loud, despite my attempts to fix it it's running fine and balances up, passes the WD40 spray test, but still chuffs. The chap at the engineering company I was recommended by someone on here, they have proper pedigree looking at their setup btw, seemed to imply it's common, especially on older Italian 48s. They charged me time and materials for bushing the bearing end of the carb when I specifically said it was leaking between the barrels solved the sloppy spindle but not the chuff. It's better but it annoys me! Mine are not marked, could be Chinese for all I can tell, but #1 and #2 chuffs away to itself in time with the cam. Eurocarb have a sale on, I'm seriously thinking of taking the hit on a new Spanish 48. It's dead obvious with the poor man's stethoscope, btw.
Actually, just listened to this again, if it's the carb spindles then, yes, that's LOUD. Louder than mine, funny I heard the same chuff on a 48 engine at Superfest a couple of years ago. I thought, finally that sounds like a VW .
Thanks for the help and suggestions. I’ll try the stethoscope first then take it from there. The carbs are about 15 yrs old. This only started after I rebuilt them. I’ll see what I can find Sent from my iPhone using Tapatalk
The fact you had some re bushing done points at there being other wear around the butterfly plates, or when you reassembled the carburettor afterwards you fixed the plates in the slot in the spindle slightly off centre, so they do not close as effectively, leaving a gap to chuff. It may be sufficiently small that when you balanced the carbs on the idle screws you compensated for it. Its probably worth a check before splashing cash..
If that's for me? Certainly worth checking, yes. I agree. Unfortunately, the noise I have is exactly the same as before, in between the barrels, just where it was before, the bush was only done at the throttle linkage end. I think the carb should have been bushed at the centres and well
Its the taking it apart to do machining and putting it together slightly wonky aspect I am focusing in on.
I'll check the butterfly valves, be a good opportunity to ensure the screws are holding, strange thing is, same noise, same place. When I collected then it was a bit of a disappointment that they seemed to think "they all do that, sir".
In that case he should have said so before taking your money and pointlessly going through the motions.
