6 years and unknown $

[dougs bs23]

So after 6 years and i have no idea how much $ I got this thing out of the garage today.  Fired up nicely, but,,,,,  got this miss/pop through the exhaust and i cant seem to figure it out.  maybe vacuum leak?  all new hoses and regightened everything i could think of,  dist cap looks good, maybe a bad wire?    Got the idle up tp 25oo with vac connected and set timing at approx 36/38 * according to the timing, initial fire up post on another thread here did what i believe is a proper cam break in 2000k rpm few minutes, then slowly increasing to 2500 for a total of 20 minutes or so,  but cant seem to figure out this pop    Have a list of thing to finish including bumpers, side marker lights, some interior stuff and im sure other things will come up as i go,  but this miss/pop really has me stumped,  another thing is when i put it in gear wants to stall out,  oh boy more things to figure out,  So come on and throw suggestions to me so i can make it right.
70 coded 340, dougs headers,  lunati cam #60403 edel intake, quickfuel carb HR650, pypes exhaust 

[brads70]

Looks good! I'd  suspect an air leak in the exhaust causing the pop?

[Chryco Psycho]

Congrats , it could be lean or a leak into the exhaust as Brad said causing the pop

[torredcuda]

If you don`t havethem  try and borow a compression tester and a leakdown gage.Hate to say it but it could be a sticking lifter/bent valve or bad cam lobe.Obviuosly try an eliminate all the easy stuff like bad wire or spark plug, carb issues etc. first.

[dougs bs23]

bad lobe would be bad,,,,,  just bought this kit with lifters and springs on top of the 500 i gave the machine shop to redo the heads    but ill start with comp test next week and see what happens.   anyone near me have a leak down tester i can use?

[dodj]

Looks good! I'd  suspect an air leak in the exhaust causing the pop?

Last year my 440 was behaving as you describe. I found the #3 cylinder header tube cracked. Replaced the header and no more popping.

[HP_Cuda]

First things first, borrow a known carb that works and try that out.

Then move on from there. I would pull plugs and then try to identify the cylinder that is popping.

[joelson6]

it was doing the same thing on my 440 and it turned out to be a fouled plug.

[dougs bs23]

Started looking into this today. Pulled covers and plugs everything seems to move freely. So far checked pushrods and they're straight, rockers look good as well. I hate workin nights so not a lot of time. Tomorrow ill check compression get new plugs and wires fire up and go from there.

[dmk67]

Did you try fresh gas ? worked for me.

[dougs bs23]

Lol on gas new tank,pick up and lines. Unless sunoco sells old gas. Carbs probably it since I took it out of the box. So got to tune it too. Looked at it a little and the a f screws were only out around 3/4 turn,thinking they need about 1-1/2 to 2.

[dougs bs23]

   retightened the header bolts, new plugs and wires, tweeked the carb a little and no more pop.   So now I can tune in the carb and I believe all is good    Had me worried that something serious was wrong but simple little things gor me all in a panic.  Now its on to the next item on my list. 

[HP_Cuda]

Yep first thing to check (at least with a Holley) is if the idle mixture screws are out 1 1/2 turns and go from there.

Glad you got it worked out!