well, i drove today for a short distance in the 7 and when i shut the engine off today i heard a backfire almost a second later.
any suggestions of what might case this?
and can anyone help me tune my holley carb w/o the muffler rich/lean device?
thanks.

 

I remember when my choke got stuck out it would backfire like a .50 cal rifle. i had to unhook the choke cable but I guess I would say to check if the choke is disengaging.

 

Did you just install a header system? Did you just install the carb system?
You could have a exhaust leak. a intake leak.
The throttle plate may not be returning to the closed position.

 

no the carb and headers have been in there for quite awhile. i might have and exhaust leak though.

 

i know mine will make a cannon sounding backfire when you rev to 4k and shut the engine off.

 

Mine will usually let off a fart after shutting it down. Always been that way since the RB exhaust went on. Pretty sure there are no leaks in my system. Sounds more like a poof than a bang though...

 

most of the time mine just poofs and shoots some fire. others if i get really on it and shut it down(which might i add i never do) it goes bang really loud

 

Pretty typical on a carbed engine,especially with an aftermarket exhaust.
When you turn off the key,the sparkplugs stop firing,but since the carb is mechanical,it still lets out fuel,until the engine stops turning.That fuel cant ignite,since the sparkplugs arent firing,so it collects in the exhaust and will spontaneously ignite if the temps are high enough.With EFI engines,turning off the key stops the injectors and the sparkplugs,so you dont get that after-burning effect.
My old carbed engines did it with the stock carb and with the Yaw carb.Somethimes a bang,sometimes a poof.It depends on the fuel/oxygen ratios present each time it happens.......ever fired a potato cannon? Depending on how much/little fuel you spray into the breech,you can get a "poot",or an ear shattering "BANG".....even though its the same device.
I only noticed it with the RB exhaust system,but I wouldnt doubt that it still happens on stock cars too.Your just less likely to hear it through cats and the well baffled stock muffler.