Ok thus is new one. I have 72 supreme, stock 350. I have issues with carb, if car sits for awhile I have to pour gas into carb so that it will start right away. Did that this morning, poured in gas ( maybe little more than usual) car cranked several times, started, ran few seconds and then BOOM. Looked under car, muffler blown apart, didn't even know this was possible. Car had been sitting about a month. What could cause such a violent explosion? Scared the hell out of me, thanks

 

Too much raw gas.
The unburned gas was pumped into the muffler where it vaporized and was ignited by the hot exhaust gas once it did start.
Pouring gasoline into a carb isn't the best practice.

 

As Charlie stated this is a self-inflicted wound caused by flooding the engine with fuel.

 

Figured as much but have been doing it long time, guess it caught up. Other than new muffler and fixing n g carb should I worry about anything else being damaged? Also I've never heard of gas in muffler. I this normal? If so why doesn't it frequently happen. Besides pouring gas in carb, something I've done hundreds of times what else could cause it. If anything?don't get me wrong I believe what you say and will stop the process just wondering why now after all this time? T h x for response

 

No gas in the muffler isn't normal, which is why mufflers don't normally blow up. In your case, pouring gas in the carb resulted in an overly-rich mixture, which flowed right out the exhaust valve and into the muffler. That's why it exploded. No, you are not the first person to do this. Use starting fluid in the future, not raw gas. Exploding the muffler is the least of your problems. Pouring raw gas into the carb can wash past the rings and clean the oil off the cylinder walls. This leads to premature ring wear.

 

If fuel is needed, use a funnel and pour the fuel into the vent on top of the carb instead of into the throat.

 

I use a chemical applicator bottle like this to prime the carb through the vent opening.

 

Thanks for info sorry for next question but vent?

 

In the top of the carb...a miniature stack/pipe that goes into the fuel bowl. The previous suggestions of filling the bowl through the vent allows the carb to meter the fuel by the carb vs. a flooded/too much gas situation.

Good luck!!!

 

 

Gotcha, thank you so much. Probably won't use it now, don't want to start car with muffler exploded, other than terrible noise don't know what else to expect. Would starting it cause more damage? At least I know for future what vent is. Hope you had great x mas

 

Estimating an ounce or two of gasoline should be sufficient, don't fill the vent to overflowing.

 

Running the engine with the blown out muffler won’t do any damage.

 

Just curious - do you believe the muffler was original to the car? I've owned a couple older vehicles ('67 442 & '72 442) late 60s and mid-70s. I went through a muffler on each around 50K miles. Or, was the muffler an aftermarket OEM style or merely an aftermarket? I've seen several mufflers fall off of cars on the freeway - I've never seen one explode. I'd love to see a picture of it.

 

^^^This

 

Turning off the key momentarily while driving and then turning turning it back on will give you the same result. In high school we used to do it passing the school when we were skipping school. Today you’d probably get arrested as it sounds a lot like a gun shot.

 

Thanks to all. It is not original muffler

 

Someone did that to me in the 90s while I was bicycling on a 2 lane road in the boonies. Scared me so bad that I completely froze, and I didn’t even wobble. He didn’t get the satisfaction of seeing a cyclist pile up in the ditch. Ha, joke was on him that day!

 

Yep we did that all the time. Dad brought home a 65-66 Ford Galaxie for me to get as a first car, Went out with it with a friend and I did that key off trick and blew the muffler up. Later I had a 67 Malibu 'vert with a 283 powerglide and dual glasspacs with tailpipes all the way to the rear bumper. It did great flames out the tailpipes!! Ah Youth...!