Does bad gas make my Marilyn burp?

What are the signs that I may have gotten some bad gas in my car? I am currently experiencing small burps and farts during deceleration in 3rd and 2nd gears and am trying to narrow the cause. I have leaned the mixture on my dual Kadrons significanly with no change. Checked for exhaust leaks and crud in the carbs. Both checked out OK. I installed a Pertonix Igniter, Flamethrower coil and matching spark plug wires a week ago with no problems during a week of driving. Checked valves and all were within tolerances. Timing is at 10 deg. BTDC. Compression on the engine was set up to run 87 octane.

Any suggestions? If it is the gas, is there anything I can do?

Are the carbs balanced side to side?
This is what caused my popping on deceleration when I was setting my Kadrons up. One side of the engine was leading the other...

Brings memories of the crap gas from Carlisle. Mny of us had an issue with bad gas there. Makes the car burp and fart on acceleration and deceleration in 2 and 3rd. Not in first because there is enough compression to clear it up. But. I found that 2 tanks of HIGH Octane cleared it up.

At Carlisle I turned up my REV's a bit to hide the farts while I waited for my gas to run out.

I tried adding Octane BOOST but that didn't do anything.

My 2 cents, put the expensive stuff......

I just figured these little cars were flatulent -- like sheep.

John,

What does your plugs look like?

If the fuel is contaminated, water will leave a residue on the electrode.

Have you checked for a vaccume leak? There could be a leak at the caruburator / intake manifold base or at the intake manifold & cylinder head.

Is the engine operating temperature higher then normal?

Water in the fuel increases the compression ratio and could effect the operating temperature determining the amount of contamination.
Remember the add on "Water Injection Systems" in the past?

Fuel cools the Pistons & Valves and if the fuel has water suspended in the mixture you could have obviously adverse effects.

Inside the float bowles there should be a sign of water if the fuel is contaminated, remember fuel & water doesn't mix.

Good luck,

Jack Blake

My experience with "bad gas" was that you got half the normal miles per gallon and a bit less pull in the engine. This was frequently just moisture in the gas itself, probably pumped from the bottom of a gas station tank that all ready had water in it. Have not experienced it in a VW type engine. Probably would be a lot more noticeable in a small engine than a large v8. Be wary though. When my gas gauge died and continued reading 1/2 full, I did run out of gas once. Later problems confirmed I had pulled some water through the fuel system from the bottom of my gas tank. This resulted in a pair of seriously corroded Webers, and much expenditure of funds to repair. Periodic treatment with 1/4 cup of denatured alcohol in a full gas tank is good insurance for cars that are weekend drivers. About once every six months should do the trick.

Carbs are balanced.
I pumped 1/2 a tank of 89 octane and the car is running a little better. Noticed some residue looking into the carbs and cleaned it out.
I was thinking that the $1.90 ARCO 87 octane was a deal here in So Cal. I should have known better.

If you have access to 93 octane, put that in. That's what I'm using here and even with the recent higher prices at the pump, you don't feel the price hike much since the tank is small, but your car will run a lot better.