440 rough idle

[71green go]

Ok...been chatting with Ron on the phone about my ongoing rough idle....I am so glad he called me and gave me some ideas to check out!
my engine is a fresh rebuild but I have never been able to get it to idle properly...
The first thing I did was pull the wires from each cylinder one at a time......and I checked the temp at each header with an infra red temp reader....seems cyl number 7 was cold at the header tube pulled the plug and found this..the gap must have got bumped closed when installing them, also all the plugs were very black from running rich until I set the carb correctly


After I cleaned and set gap on all plugs the engine does run better, but still idles rougher then I expected.....here are some pics of my current setup....
Ron the carb does only have front idle screws...no rear ones










tomorrow I will remove the valve covers and make sure the valves are adjusted properly....and will repost

[firefighter3931]

Good detective work Steve 

Your 750dp has 2 corner idle so no secondary mixture adjustment 

Did you ground out an ignition wire and look at the spark color ?

At this point i would re-check your valve pre-load adjustment and throw a fresh set of XR5 plugs in the motor and gap them at .035 

From my experience ; once the spark plugs are badly gas fouled they never run right....even after cleaning. 


You're getting closer 



Ron