While rebuilding my carb and double checking against another old carb i've got i noticed the following

What is this (in the circle)



And why is has the one i have on my current carb have a blob of solder blocking the top hole and the one off the other carb has not.



Cheers
Carl

Hi Carl,

OK - This is a modification introduced very early on in the life of the B172K engine. The brass plug with the hole was a pressure bleed off from the accelerator pump jet housing to reduce the amount of extra fuel injected. (it was designed for markets with a more stringent emission regs.)

On the UK market it was found to give flatspots under acceleration and a service fix was introduced late in '86' I think (the fix was to seal the jet with a blob of solder). This did not entirely cure the problem and a twin nozzle acc. pump jet was introduced (the first version had only one jet feeding into the primary venturi).

I would imagine the carb you have with the open jet came from a car that either "was missed", or on which the customer never perceived a problem and the mod was never carried out. (it fix was only done if the customer moaned!).

The difference it makes is in reality very small (generally) but I'd stick with the sealed jet.

From memory the last of the B172K carbs did not even have a drilling in the chamber for the jet - and certainly the similar carb on the 400 series never did have.

Hope that helps

ALL the best - Mac.

Cheers Mac (again)

Just wanted to make sure it wasn't some wierd bodge.

Cheers
Carl