anti backfire valve

[zhead240]

 recently when i'm at a stop i hear low sounding backfire.  does that mean i need a new valve? i looked them up on ebay. used $45 and new old stock $396 us.

[Yarb]

There could be a multitude of various issues going on. What’s your diagnosis of it being a defective valve. Need some more in depth details.

[zhead240]

my diagnosis is the muffler is back fireing when i'm stopped or slowing down. don't hear it when up to speed. some one said was the carbs . i don't want to go down that road.

[Yarb]

Again there are a lot of options here beginning with checking the timing and go from there.

[zhead240]

might have to go to my mechanic

[Patcon]

Valve adjustment would also be low hanging fruit

[SteveJ]

Does your car still have the solenoid to keep the throttle from slamming shut when you get off the gas?

If it doesn't, then you have a sudden rich condition when you lift off the gas. 

[siteunseen]

How old is the exhaust? I had an 325is that would pop out the back downshifting. The muffler was bad but I liked it.

[zhead240]

not 100% sure but i believe i still have the solenoid. all the anti pollution still on this 72.  can't recall how old exhaust is but i remember replacing muffler 10 years ago.

[SteveJ]

But is the solenoid working?

[zhead240]

how can u test? and where is it located

[Yarb]

Check the FSM. I’m sure it’s just jumping power to it and see if the solenoid engages.