What are my spark plugs telling me ?

[Tony 73]

Cuda 440 Engine sounds good and revs nice, BUT fumes are hard on eyes and nose compared to my 438 stoker in my challenger, both running on 100 octane and both have same plugs, Champion J12YC .

Have read that a lean engine can cause this,  don't think my plugs look lean but I no expert.

Opinions please

[Tony 73]

Rear two are out of the 438,  definitely lighter colour, looks like cuda ones are too rich ?

[MoparLeo]

They are done..put a new set in and drive it. Just idling around and they will just load up. Definitely rich.

https://www.motortrend.com/how-to/10-factors-that-affect-spark-plug-heat-range/?wc_mid=4035%3A19532&wc_rid=4035%3A1085290&_wcsid=830AE02F5E48272A70C309A0098167BEBFAF833432BF5543
https://m.roadkillcustoms.com/understanding-spark-plugs/#axzz3Nyc7Blpj

[Tony 73]

Plugs cleaned and back in. They were band new and mate and I gapped then to correct specs.

Will run engine again tomorrow.

May have to wait till I get car legal and then take it to an expert.

An thoughts appreciated.

[Mr Lee]

Definitely looks rich.  This is a new build yes?  Carb probably needs tuning.  But before setting up the carb, make sure the engine is warmed up and the timing is dialed in.

Chryco wrote a carb tuning guide on here.  Let's see if I can properly add a link to it...   
https://forum.e-bodies.org/reference-material/18/holley-or-similar-tuning-tips/215/msg2058#msg2058

[Tony 73]

Thanks Mr Lee and MoparLeo,

I should have done more research . Both the Champion and Autolite spark plug picture pages say my engine is running rich and too much idling .

My motor is an old build with maybe 20K miles on it. Was last running 3 yrs ago, only been started and idling over last 4 months. Timing is good but will recheck. Plugs are brand new and only done 30 min of idling. Can be easily replaced. Need to get engine up to temp and long drive, but till I get car certified I can't do any more than go up and down my drive.

Thanks for the links, I will look at them today.
Cheers
Tony

[Tony 73]

Couldn't resist looking at the links, brilliant, love the detail of the one written by Chryco, , will be invaluable . The video on by Roadkill customs fantastic too.

Thanks again for posting the links 

[Tony 73]

Tried to do some research on my 6 pack carbs, only got mixture jets on the middle carb, majority of info says wind screws in and then come back out 1 1/2 turns  which is about where mine were. Have moved them back in 1/4 turn. Until I get out on the open road this is about all I can do for now.

I am thinking of buying an Air/Fuel ratio sensor kit. Got 4 cars I can use it on. Weld a plug on each exhaust system so I can test when I want to. Wild some research and ask a friend here in NZ who has one in his challenger.

[Chryco Psycho]

The end carbs have idle mix screws in the base plate under the bowl , often they are capped , I take a small drill from under the carb & make a small hole to pop out the caps then set those screws about 1/2 to 3/4 of a turn out , the front carb can be adjusted while the engine is running , they usually are set wrong from the factory .

[HP_Cuda]

Based on how rich you are running I believe that is beyond what air/fuel mixture can clean up. Unless you opened them up to the max.

Most likely you will need to re-jet for your motor. Also check the power valve on your center bowl. You want to be 1/2 your vacuum readings for your motor. For example if you are pulling 14-15" vacuum you want a 6.5 power valve.

[Tony 73]

Appreciated the feedback guys.

I have spent so much time and money on the rest of the car so should do the same to get it running smoothly.
The engine , carbs are a new combination so will do as you say HP_Cuda, check my vacuum, match the power valve and then final adjustment with carb screws.

Cheers