36 to 39 Gas Tanks

[conwayde]

I have a later year (not sure what year) right-hand side gas tank on my '38 Knuck. The left side is fortunately original. It has a jerry-rigged petcock on it now (very ugly and incorrect, but at least functional) and I want to replace it with the correct one. I know the later petcock/gas line insert is different than the early models (male vs female).

Has anyone ever converted an older tank by welding/brazing the correct insert onto an older tank? I believe the early tanks had a female insert with 1/2-20 SAE threads (or at least, that's what the correct '38 petcock appears to fit into.) Does anyone know where I could get a proper insert to conduct this little feat of trickery? I'm afraid I have to hit the lottery to afford an original tank, and it doesn't make sense to cut one out of a repop.

My other thought was trying to track down a tank in such poor condition (except the petcock insert) that it would be useless to anyone but me. Unfortunately, that hasn't happened yet, unless someone here has such a beast he is willing to part with for a mere pittance. Did Flatheads have the same petcock inserts as Knucks did for those years?

Any help, ideas, or suggestions would be appreciated.

[46EL]

What is needed is for someone like the Olsens to make a complete and correct repop fitting so a 40 to 46 RH Tank could be converted to a 36-39 style Tank. I also would like somone to make a correct early Oil Tank Fitting so a 37 Big Twin Tank could be made into a 36 Knuckle Oil Tank???

[Chris Haynes]

What is needed is for someone like the Olsens to make a complete and correct repop fitting so a 40 to 46 RH Tank could be converted to a 36-39 style Tank. I also would like somone to make a correct early Oil Tank Fitting so a 37 Big Twin Tank could be made into a 36 Knuckle Oil Tank???

It would be a simple lathe project to make the fitting and drain plug for the early '36 which is welded in. The later ones are swaged. But which '36 tank are you looking for? I know of five variations.

[conwayde]

Chris - are the '38 tank inserts simply welded in? They appear to be welded in on my left tank. Not being a machinist, if I took my problem to one, would he be able to make the insert, closely matching the left tank side as an example? Sounds like a solution to my problem, if it's this easy. (Somehow, this sounds too easy?) Then, I have to find someone competent enough to cut out the old one and weld in the new.

[Carl Olsen]

Send it over and we will make the repair.
Carl and Matt

[46EL]

I went through all my spare early sheet metal and found a 36-39 LEFT Tank but no rights. Carl should be able to help you!

[conwayde]

Thanks for the replies, everyone. Looks like Carl's the guy for the job! But, it will have to wait until this winter - the bike is riding just fine now, even with the ugly petcock, and this kind of project has to wait for cold weather!