The Tank on my 69RR is about 8 years old and I will be pulling it off. How is the best way to be sure inside is Clean ? I will be putting in my rebuilt 440 and want to be sure of the Tank.

Thanks Tom C.

If it was me and I was planning on dropping the tank anyway, I would just remove the sending unit and do a visual inspection through the hole.

Maybe replace the sock on the sending unit?

If it looks clean and doesn't leak I wouldn't worry about it much.

take it to a car wash & blast it out with the wand, their soap then rinse then take it home & set it on sawhorses above a heater to quickly dry the water droplets. then as said a good visual/replace the sock (toss it/use aftermarket filter in some apps). I'm assuming your sender reads correct. I'd prep/paint or coat the outside & no opinion if an inside pourable coating is a good move (if so it'd have to be done right so no flaking). If any doubt I would get a new Spectra (Canada) tank & there was something about counterfeit Spectras but tanks are pretty trouble free.

Unless it sat with old gas in it for years, I wouldn't even worry about it.

If its not rusty you can add a bunch of acetone, slosh it around, rinse with fresh acetone a few times, should do a great job. Just be cautious, its very explosive stuff, a spark with ambient fumes etc. Can go boom

Rapid's idea isn't bad and if you follow it up with Scott's idea, the acetone will remove the water for you. Acetone is about as explosive as gasoline so do be careful. An old-school trick I use is to put a large magnet at the low spot of my gas tank, so if there's any free metal (aka rust or whatever) it gets held in one spot and doesn't get sucked up by the fuel pump.