Remove tank, fill with water. NO gas, NO gas fumes, what can happen? Pretty standard for gas tank repair to fill with water and weld.
Just thinking kind of outside the box. Did you ever think about checking some one that sells replacement airplane parts?
One thought would be to look up a small machine shop or two that does general machining and repairs. Take the cap and ask for a quote. It would not cost anything for an estimate. Could ask around as well. There may be a friend of a friend who could do it or a retired machinist who has a lathe that could do it as well. The old cap sounds like it lasted a long time and a new cap would last many more years. It may be easier & less expensive to have a new one made rather than tearing the car apart to install a new neck. Likely the aluminum was used for cost and it would wear vs using all stainless and risk wearing the neck threads out. We use a fuel lube on the aluminum fuel cap and filler neck of our airplane. Aluminum against aluminum is dry and very sticky. The grease helps with screwing the cap in and out as well as by stopping the aluminum from oxidizing & bonding the parts together. A lubricant would keep the threads on your aluminum cap from wearing against the stainless thread. The grease in the threads would definitely slow down wear. A white lithium grease would probably work as well. https://www.aircraftspruce.com/pages/ep/lubricants/ezturnlube.php
Good idea, really appreciate the info. I would not attempt to weld on a new neck, probably end up buying another gas tank at worst. I don't really want to do that. Don't know of any machine shops in the area , have to check around.
Done it lots of times, My wife said she would kill me if I ever blew myself up doing it, so I make sure I do it correctly. Even after cleaning it I still stand back with a long torch to see if I get a "woof" out of the filler, but its not going to explode
'Risky business'... I helped Rich Starett in high school machine shop one afternoon, he had to weld a pinhole in a weld on a MOON tank. (2 gal., aluminum w/ welded caps onto a spun body) I filled it to the brim with water, rinsed it once, refilled it. Starett lit the acetyline torch, placed it on the weld and with a 'WOOM!' blew the end cap right off the tank, and it went clear to the opposite wall! 20 feet! Starett looked odd with no eyebrows. "Dem fumes was lurkin'!' I sang a little blues ditty after class, that was the lead line...
I would personally rather look for a cap or someone who could make one. Messed with cutting out a Model A gas tank years back , learned my lesson.
Yeah, it's handy having a buddy that's a machinist and doesn't have his own car, so he likes making things for me. To bad you're not closer, he could make one I'm sure.
I've got a spare cap and (aluminum) neck, same as I used on my avatar altered - the thread on the neck actually measures 2.470" dia. and the thread is 16TPI. The cap has a trick little flapper valve that would vent no matter what the flow - I'm sure you could silicone it shut if you wanted. I think I'm in it about $30. Not sure where I got it.
I cant believe that on one has an extra cap, and that no one else has run into this problem with the earlier Rock Valley gas tanks.
Just borrowed a thread gauge. The thread pitch is 1.50mm. I counted 9 threads on the half inch gauge. Does this mean that the thread on the neck and cap are 18 threads per inch?
Joe, you need to get a thread gauge for SAE (American) threads - I just checked a filler neck that was on my Model A's tanks, Inc. tank and it's 16 tpi, though it's 2 1/4" dia. 16 TPI is a really easy thread for manufacturers to use. A dial caliper should give you an accurate diameter measurement on the threads. Hope th is helps.
Here's a little more comprehensive SAE thread gauge, its a "General" brand No. 251 - pitches from 4tpi to 84tpi. It's a little older, the new ones available in Amazon are slightly different and are about $35 - you might be able to borrow a good gauge from a machinist friend.
Went out and bought an SAE thread gauge. The gauge measured 16tpi.The previous tool I borrowed was metric.
I'd go find someone to make a Custom, one off cap. Probably be a reasonable price, and you could personalize it, and have it made from aluminum or stainless.
If it was me, I would buy an original style gas cap, and take your old worn out gas cap, drill a hole in the center of it and file two notches in it. Screw it on one last time, and use an original style gas cap on your newly made adapter. Or... http://www.cgj.com/store/product/bt-76409-weld-on-aluminum-filler-neck-and-cap/ http://www.ebay.ie/itm/2-1-2-ALUMIN...802721?hash=item3acd6133e1:g:HbQAAOSwZ8ZW2kRE Right size and thread pitch...
I will start contacting local machine shops tomorrow, price is not the problem, getting someone to do may be.
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