exhaust backfire

[socalaquaholic]

help !! i have a chrystler 440, wait, thats not the problem, or is it ?? ha ha, anyway, aside from doing a valve job, just yet, what could be causing a back fire from the exhaust, usually only on the left side, but sometimes both sides. it does it only when warm and after a rev of 42oo rpm. the timing is right on, valves adjusted twice, new plugs, i just dont wanna think its time for a valve job yet, any more ideas ?? the induction is 2 eddlebrock 600s hydrolic lifters androller rockers
thanks for the ideas !!

[wet and wild]

SO CAL, HATE TO TELL YOU, BUT IT DOES SOUND LIKE BAD VAULVE OR VAULVES.GOT A COMMENT FROM DRAG RACER.DAD AND NEIL IN LAGRANGE CA.I MUST SAY AS MANY PROBLEMS AS YOU HAVE HAD, YOU NEED TO CALL NEIL WHO IS INTO 440 HEMIS.1-209-852-2286,SPEAK TO NEIL CASE,HE WILL SCHOOL YOU,OR GUY AT BALBOA AUTO PARTS.GOOD LUCK BRO,SEE YOU AT THE LAKE IN MY BOAT OR YOURS.JOHNNY THE OLD MAN,HUH.LATER DUDE. Originally posted by socalaquaholic:
help !! i have a chrystler 440, wait, thats not the problem, or is it ?? ha ha, anyway, aside from doing a valve job, just yet, what could be causing a back fire from the exhaust, usually only on the left side, but sometimes both sides. it does it only when warm and after a rev of 42oo rpm. the timing is right on, valves adjusted twice, new plugs, i just dont wanna think its time for a valve job yet, any more ideas ?? the induction is 2 eddlebrock 600s hydrolic lifters androller rockers
thanks for the ideas !!

[Maverick]

[QUOTE]Originally posted by socalaquaholic:
[B]help !! i have a chrystler 440,
If your problem is high rpm and high load only, then check you plug wires - bad or bad and routed against one another can cause a "cross fire". Also, check your rotor bug in the distributor cap - sometimes they have a 'carbon trace" to the distributor shaft and creates a "miss"
Otherwise - very bad valve problem seems likely.
Good luck
Mav

[Costello]

If it does it only when you bail out of the gas; on deceleration, it may be an exhaust leak at the manifold or a cracked header also. That is no good because the cool air entering will cause you to waste a valve.