backfire

[Rolling_Thunder]

I get a backfire on hard acceleration when im shifting...  any ideas?  Timing ? Carb need adjustment ?

[67_Dodge_Charger]

Sounds like timing.  Or a cracked cap.   

-Robert

[Rolling_Thunder]

cap is alright ---  ok  stock 440 - what is the timing suppost to be with a manual transmission...   i hear TDC, 5*BTDC, 10*BTDC....     right now it is at 10*....     

[Chryco Psycho]

could be going lean

[Nacho-RT74]

 

I'm on same deal... also some stumbling when engine is warming up and engine sometimes try to dye when I'm running and stops suddenly

[Rolling_Thunder]

ok - so you're suggesting i play with the carb and leave the timing alone i assume....   I will try that

[firefighter3931]

Check for vacuum leaks.


Ron

[Rolling_Thunder]

well i 5took it out today and it still is giving me problems....      when im hard into the throttle and shift to second it backfires and stumbles....      on compression it also knocks in the exhaust at times...  this is probably just my imagination as i can saee the headers from the seat and im sure it just sounds loud because of the lack of insulation and floor....       i guess i'll have to hunt down vaccume leaks and play with the carb some more....     maybe the carb is just too small....     i threw it on just to get the engine up and running and it runs great unless it get into the throttle hard....   

[67_Dodge_Charger]

Sounds like timing.  You are loading up on fuel and the engine misfires.  Then when it fires it wakes up the neighborhood dog. 

It is odd that you get backfire at the shift.  That means you are getting a backfire after a high rev rpm and a sudden lift of the gas pedal.

A vacuum leak?

good luck
-Robert

[Rolling_Thunder]

not finding any vaccume leaks...     like i said the timing is set at 10*BTDC which it seems to like very well...     it is most likely leaning out when i get on it really hard...     when i drive it around without getting into the throttle it does not backfire...     

[jgbailey57]

i bet it's lean.  how did you check for the vacuum leaks?  just the hoses?  it could be leaking between the base of the carb and manifold or at the intake gaskets.  easiest way i check is to spray some carb or brake cleaner around the gaskets while it's running.  if it revs up you've found your leak.

[Rolling_Thunder]

no - checked all the hoses and the carb to manifold and manifold to head seals...   they are all good...     hmmmm....    probably really lean...      im not even sure what size carb is on it...    just kinda ran what i had

[jgbailey57]

check the spark plugs, that should tell the story.  if the porcelain inside the plug is light tan or white you know it's running lean.

[Rolling_Thunder]

hmmmm    it only does it under load as well...   typical story for running lean ?