Brass pin stuck inside Zenith TIN 40

[Einar Irgens]

Underneath the accelerator pump nozzle there sits a brass pin. I am not quite sure what it is for. Normally, the pin will fall out when the carb is turned upside down. No in this case. It would not sit any firmer with superglue.

First I soaked it with various chemicals. After a few days, I heated the body thorougly with a propan torch, before I used the nail to press from inside the cavity. But no, it is completely stuck.

I am now considering drilling the pin away, but will this influence the operation of the accelerator pump? When I opened my first pair of Zeniths, many years ago, I found that one of these pins had been replaced with a steel screw of similar size. How sensitive is the system?

[1QuickS]

I like the nail, use a flat tipped screwdriver as a lever to press nail into pin, pre-heating would be a good first step, an acetylene torch can be used fairly generously and it will provide more heat than a propane torch. The aluminum body will not melt unless you get a very hot and prolonged application of heat. You could put two of the accelerator top cover mounting screws back into their holes and place anther nail across them to use as a fulcrum for the screwdriver.

The brass pin is a check valve to prevent fuel from being sucked back into the fuel pump during the suction stroke which would normally fill the pump from fuel from the float bowl. The seal between the bottom of the brass valve and the orifice at the bottom of the vertical fuel gallery where it sits must be in good, sealing condition. A stainless steel ball bearing is a suitable replacement provided it has clearance with the fuel gallery.

If you drill the brass valve it will probably start to spin before you drill into the aluminum body...probably.

[Einar Irgens]

Thanks, Paul. I did use various sizes of flat screwdrivers. Levering and twisting them between the nail head and the edge of the cavity provided a rather strong force, strong enought to bend the nail. I also tried using a shorter piece of a nail and a pair of water pump pliers.

Will report status when I have drilled through the pin with a 2.5 mm drillbit.

Isn't the return of fuel prevented by the glass ball inside the nozzle?

[1QuickS]

Yes, but the brass pin acts as a secondary check valve. Odd that the pin is so seized that your efforts have been thwarted.

Perhaps a few strong taps on the top of the pin would loosen it enough so the levering would press it out.

[Einar Irgens]

Finally. It took 1 1/2 hours and two worn out 2.5 mm drillbits.



Think the channel is pretty much undamaged.
The pin showed no signs of moving or slipping. I had to grind all of it to crumbs.