440 tuning

[Moparbandit]

The 440 im running is so rich it will gag you at an idle... its been bored .030 over and has a purple cam .509 in it... the timing is set at 36 total advance. up top she has a TM7 intake and a 750 demon carb... ive tried jetting the carb down and messed with the mixture screws... that seemed to work for a while but the problem has now returned... the engine has less than 500 hrs on it maybe 200 miles since the rebuild... id like to not have to tear it apart again but this has to be fixed!!!!

any help or thoughts would be awesome thanks!!!

 

[Chryco Psycho]

Well basically the cam is the problem , long duration , lots of overlap & low vacuum .
The power valve could be an issue , check the vacuum reading at idle in gear , the power valve rating has to be lower than the vacuum reading so start there , if you get a manifold vacuum reading of 5" use a 3.5 power valve for example .
I bet it pulls great 2800 up !!

 

[Moparbandit]

Thanks for the help... it does pull good... the last time we I raced it I'm pretty sure my ears touched when it launched... haha

 

[Chryco Psycho]

Landed that hard Huh LOL

 

[Challenger340]

You can replace the power Valves, hook up a Vacuum gauge, and pull timing ahead until you achieve the highest "steady" reading on the vacuum gauge without fluctuation.
Then,
test drive, and load test it for "ping", backing timing 2* at a time until good.

If that doesn't work, you can simply remove the power Valves alltogether, and install solid plugs instead,
then
simply jet up 4 sizes.
No more PV leaks period at Idle, to burn your eyes, and then follow same procedure above.

The .509 ain't great for vacuum, but no reason to go tearing it apart, just get as much "initial timing at idle" in it as possible, without "ping" under load.

 

[Moparbandit]

The second option sounds like its worth a try... I've vacume tuned it and it will run great for about a week and then its back to being very very rich

 

[Adrian Worman]

I had a similar issue with the 440 in my Challenger, but after installing an FBO advance curve kit I managed to dial in 20deg initial advance with 36deg all in at 3200rpm, runs super clean, idles perfect and does'nt burn your eyes anymore, and that was with an Xtreme Energy .507/.510 cam, makes the carb so much easier to tune with decent ign timing

 

[Chryco Psycho]

removing the power valves uses extra fuel all the time , you can get power valves down to 1" rating so I would try that first