In cab tank isoliation

[cerial]

This sexy beast just arrived from LMC.
72 tank with eec.









I want to start fitting it in in my 87 square body tomorrow.

There will be a bit of fabrication to weld some studs to the existing cab and maybe modify the neck but nothing like building a tank from scratch.





I am wondering in stock form or as an upgrade if there is any rubber between the cab and tank bolts to isolate it?
Any rubber under the tank to isolate it?



I have 8" wide by 30' long of convenor belt that is 1/2" that I paid a dollar for and seems like it would be perfect to lay on the bottom of the tank. I could also take a hole saw and cut some 2" circles for the studs to pass through and place those 2" circles on the back and front of the tank to isolate the studs on the top.

Or is the isolation idea a horrible one which will cause squeaking all over the place and I will be better off mounting it hard and using aluminum washers which it looks like the factory did.

['68OrangeSunshine]

Sounds like a good idea to insulate your tank. I can't predict what the set up will sound like. If it squeaks, shoot WD40 on it and tighten more. I can't say if you need to have the tank grounded to the cab for electrical reasons. You can always use a grounding strap for that if the sender doesn't read right. I don't recall any cushions under a '68 stock tank. Polyurethane is what squeaks, anyway.

I salute your sense of danger -- putting a behind-the-cab tank in a Squarebody. Remember, you are swimming Upstream for a purpose. What that is IDK.
I get so tired of Mama's Boys pulling their perfectly fine, proven safe, in-cab-tank out and getting a Blazer tank in the back, just so mama doesn't worry so.
I have had fuel-feed problems with belly tanks in the past, and prefer the in-cab unit. Fill a lot faster, too.
I once saw an Orange 69-72 K/5 Blazer in a Safeway parking lot in Tucson. It was modified with an extra pickup tank behind the seat, plus the stock belly tank and a diamond plated aluminum contractor's tank where the backseat would be. Fuel capacity must have been 60 to 100 gallons. It had White Sands NM base stickers on the front bumper. Years ago before cell phones had cameras. Before cell phones. even.
You are a First Class Danger Boy, with an in-cab tank AND that NBC-proven explodes-on-contact outside frame tank. Well done.

[Greasey Harley]

My suggestion (for what it's worth)
If you do isolate the in-cab tank, make damn sure you ground it to the cab with a piece of wire.
Personally, I would just mount it solid. Good enough for GM, good enough for me.

[randy500]

The factory tank had thick asphalt felt paper under it and behind it where it contacted the cab. The paper is about 1/8" thick, I would guess a double or triple thickness of 30lb roofing felt would be very similar.

I'm wondering why your are putting a tank in the cab on a square body though.....

[cerial]

I plan on running a grounding strap at the sending unit and another at the neck. There will be a section of fuel filler hose between the tank and newer neck so I want another ground strap.

Why in the cab is because I want to eliminate those saddle bag tanks and like easy maintenance. I did not want the tank becoming covered in salt/ice or place one where it would be hit with junk coming off the tires. No need for any type of heavy skid plate that holds mud, rocks and sand.

A "galvanized" in cab tank that uses the trucks existing vent lines and inline pump keeps the tank sealed while allowing for easy maintenance.
Sealed gas cap, vent lines going under the hood to a charcoal canister, fuel lines running in a loop to a regulator, and inline roll over valve leaves the sending unit seal as my only possible flaw.
It is a maintenance item. Once every 3-5 years pop the retaining ring and throw in a new seal. Maybe throw a new sock on the pickup. Hour or so of regular maintenance replacing the cheap part with the knowledge if the frame rubs I am not dumping fuel on the trail.




The in cab tank is not a "perfect" fix. But one that will work for what I want.
Looks like I am isolating it. Thank you for the help.