popping back

[Johnnydidd]

my 56 Merc is running great now only question I have, running at 50 mph or higher when I let upon the gas it will pop back, I love the sound but I don't want to mess something up, it has 18 inch glass packs sounds great.

 

[tinman080]

could be too lean a mixture....

 

[miker98038]

"Popping back". Backfire thru the intake, or in the exhaust?

 

[Johnnydidd]

Exhaust

 

[miker98038]

That was more common on carburetor cars, especially down a long hill on compression. I never knew what caused it exactly, something in the way the fuel gets suck thru no doubt. I've got an OT car were I can turn the fuel shut off on the EFI "off", and it'll pop on the exhaust on a long downgrade. The short mufflers are probably making it more noticeable. So it's not uncommon, and someone here will know why it happens. Then we both will.

 

[dmsfrr]

When you let off the gas pedal some excess unburned fuel mixture goes into the exhaust. The mixture ignites in the exhaust pipes instead of in the engine. As long as the carb/engine isn't running too rich it should be fine.

https://www.reddit.com/r/cars/comments/1l2a69/what_causes_exhaust_popping/

https://www.google.com/search?q=popping+in+car+exhaust&ie=utf-8&oe=utf-8

 

[Johnnydidd]

Thanks guys, love the sound

 

[50fordcoupeman]

Yes on dmsfrr's response. Unburned fuel in exhaust is igniting. Blew grandpa's muffler off his 40 Ford farm truck once. We both got a chuckle as we fixed it. He told me not to leave the key off so long next time............how did he know?? Wonderful ol grandpa!!!!

 

[dmsfrr]

..... love the sound

Times 2


If the stock mufflers on this '55 weren't like new I'd change them to something with a better sound.