440 tuning/drivability issues

[blown71cuda]

I'm looking for some extra input on 440 tuning and drivability issues. Working on my brothers 440 30 over 10.5:1 compression .494 purple shaft Hyd cam 452 heads and an offenhouser dual plane intake with a 600 com double pumper holley. It has a pretty bad stumble off idle. It's used to run really rich. I put a 3.5 power valve in due to the fact it idles in park at 10" of vacuum and 5" in drive. Those reads seem very low to me considering the small cam. Possible vacuum leak? Does anyone use gaskets with the metal tray gasket? The advanced timing is at 36 deg. I don't know what the initial timing is but I'm gonna look into that. I think the convertor is about 2200 stall. Is that not enough? It has full length headers if that needs to be known. Starting off from a stop light you have to pump it to go cause it stumbles. You cannot just ease into it. Once ur cruising it's fine. The motor is in a 33 plymouth sedan do it's a cruiser not a street / strip car. Any suggestions would be appreciated. Thanks

 

[moparleo]

Did it ever run good or is this a new engine ? How do you know what the total advance is but not initial ? My money is on the carb. Swap a known carb that runs good. 600 cfm a little small for a 440+ inch motor. Vacuum is very low. Cup your hand over the top of carb when running and if it smooths out, there is a definite vacuum leak. Pull the plugs and recheck gap and condition, fouled? Should have Champion spark plugs. RJ12YC .035 gap if standard ignition, .050 or more with an HEI or CD ignition. Give us more info. The more we know, the better we can help.

 

[challenger6pak]

I believe the cam would be a 484 lift. I have used the 484 with a Thermoquad vacuum secondary carb. I agree with Leo. It sounds like the carb.

 

[Chryco Psycho]

You could have a number of issues , 1 the carb is waaaay too small , the TQ the factory used is 850 ,
disconnect the vacuum advance & bring the total timing back to 36* it should run a lot better , have you gone through basic tuning float levels idle mix etc