I swapped the new gas tank from my retired 68' Val into my 66' Val. (leaky) The problem being different filler neck sizes. The 68' neck and tank hole are wider than the 66'. I tried using a second grommet inside the 68' grommet but this leaks. Could the grommets be sealed or will I be changing filler neck holes? Carquest has an anearobic sealing compound that states it is gasoline proof. Any suggestions?
Thanks in advance!

I think in this situation, if I weren't going to buy the correct tank for the '66, I would cut the two filler pipes after measuring carefully. I'd overlap them so that the smaller pipe (connected to the quarter panel) would overlap the larger pipe (installed in the gas tank) by as many inches as possible. Then I'd use a good grade of RTV silicone to seal the gap and over that, I'd put a length of gasolineproof rubber hose (can be had from a hose and rubber supply place). I'd clamp the hose very securely to the two halves of the filler pipe, using at least two premium hose clamps at each end.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.

Thank You Slant Six Dan. I think I can make that work. Fortunately the bone yard has not returned my call to sell them a stripped 68'.

Not in connection with gasoline.

_________________
Lasse

Signet -66 225
Holley 600 Offy-5270 Dutra Dual,regrind. cam 272 0,420 110, head shaved 0.100 slight.ported
MSD6A
A904
7 1/4 3.23

There are fuelproof formulations. But you're right, not just any ol' RTV will work.

_________________
一期一会
Too many people who were born on third base actually believe they've hit a triple.