BUILD THREAD Cost of letting your car sit for years with bad gas

[78Delta88]

Photos tell the tale. Newer fuels evaporate out and leaves a crystalline residue. When a car sits for years this crystalline residue gets everywhere and is a particular problem with carburators.

Pics show build up on primary rods and on inside of carb. Float bowl (not shown) was full of this residue. The residue as shown jams the rods and starting, tuning and driving is not possible until carburator is repaired or replaced.



The primary and secondary throttle plates are seized.

 

[Bonnewagon]

I have opened up a few of those. The old Permatex Carb and Choke Cleaner did a pretty good job of dissolving that crud. You can't get it anymore so I also try #2 oil and acetone or lacquer thinner.
Worse than that is trying to run the engine. I did just that once. The crappy fuel made the intake valves stick open. Lots of backfiring. It took hours of idling with fresh fuel to straighten that out.

 

[78Delta88]

When first moving to Arizona, I picked up several cars in the $200 to $500 range that had just sat. My 86 Cutlass set for 12 years under a tree so on that one I didn't even mess with it. Dropped the tank, cleaned it all out, new sock, new sending unit, pulled the carburetor and put an Edelbrock on it.

Fired right up and immediately blew out one of the freeze plugs. Previous owner was just using water which is common here in Arizona. Yet when you do that tends to rust out all your expansion plugs. The worst thing for a car is to let it sit.

 

[Sweet_Johnny]

I've got a Holley that's definitely going to be full of that stuff. If the carb leaked while it sat do I need to worry about buildup on the intake valves even if I don't run that carb before a rebuild?

 

[78Delta88]

Stick a camera on it. Hmmm ... Wondering if you remove carb, and from intake opening if camera probe is long enough to see back of valves?

Old school ... I used to just run ATF in the intake, dripped in through carb, mostly good luck for freeing stuck valves.

 

[Ugly1]

I’ve done both ATF and seafoam. Mostly on Fords with injection a ton of oil crust and ATF or MMO add some via the carb on older engines

 

[Bonnewagon]

I've got a Holley that's definitely going to be full of that stuff. If the carb leaked while it sat do I need to worry about buildup on the intake valves even if I don't run that carb before a rebuild?

No, probably not. The amount of fuel in the bowls is negligible. Most probably evaporated anyway. My bad experience was because I had been starting and running the engine just to move the car around. I did not keep track of the years, at my peril. A smarter move would have been to hook up an outboard motor portable fuel tank and run it off that. My '68 Firebird project has the world's cruddiest gas tank that I dis-connected from the engine. I use the outboard tank to run the engine. Works great and gas does not sit around.

I have a Holley that sat still on a 1956 Chevy for 10 years. The carb looks like 78Delta88's carb.

 

[Rt Jam]

When I used to have carburetors on stored cars. I would run the fuel out of the bowls and lines.

With fuel injection, I'm sure it's not good to sit either but so far have not found a good solution. It's even worse with ethanol.