I was going to use this isolator block that already had a nipple installed.
The problem is that nipple represents the 3rd different size nipple on the cart (fuel pump and carb are the other two). To try to stick with just two, I went to all the local auto parts and hardware stores looking for a different solution. All of the fittings I could find had threaded bases that were so large it would leave very little plastic left on the isolator. Thin plastic and the pipe taper threads would surely result in cracked plastic.
So I thought I would make my own fitting. I started with this dual ended barbed fitting:
I first tried to thread one end as is. The largest OD part of the barbs threaded well, but the thinnest OD part of the barb didn’t have any threads. I’m sure I could have used it as is, but I would really have threads cut all the way down. I have soldered brass before, so I thought I would try filling in the low spots and try to make a more consistent diameter.
This is what I used. It wasn’t pretty as the solder would drip, but as easy as brass cuts, the solder was even eaiser.
Some of the threads on the soldered areas aren’t perfect, but it will work well enough for this. This is tapped with 5/8-24 threads. These are regular threads (not pipe taper) so no concerns about splitting/cracking the plastic. I drilled the hole in the isolator off center where I had more plastic to tap.
I put some black RTV on the threads and all set.