Is it reasonable to think that with running aluminum heads the spark plug heat range needs to be raised due to the better transfer rate of the aluminum? And if so what is a general rule of thumb?

Having some dry fouling issues only when cold outside. On initial startup I believe the mixture is way too rich(still working on that)wich fuel fouls the plug, but afterwards, after engine is warmed up, it still misfires what I would call severely & the plug is very black/dry like it won't clean itself.

Runing Champion R12YC as per edelbrock E-tech spec sheet.

 

I would agree with that. Aluminum absorbs more heat from the combustion chamber vs an Iron head, therefore you would need to run a hotter plug to keep it within the boundaries. Change plugs one heat range at a time.
Remember that it's better to be too cold because the harm is fouled plugs and misfires. If you're too hot, the dangers can be preignition and detonation which can lead to serious engine problems.

A general rule of thumb is one heat range colder for every 75-100 hp you increase your engine.

I'd also recommend switching from those Champion to some AC Delco plugs.

 

Thanks for the CHAMPION website info,but have that already. Guess I generalized the question so I'll be more specific. Going from IRON heads with same combustion design/cc to ALUM, what if any plug spec changes should be made if only .6 increase in compression differrence?

By the way, who's thumb do they use for the rule?

 

I actually got it from NGK's website, but it's all the same $hit just a different pile.

I answered your question in my first post by the way, I'd run 1 heat range hotter if you switch from Iron to comparable Aluminum heads with little or no power/compression increase.

 

I highly doubt that's your problem. Your plugs would have to be ridiculously out of spec to cause problems that severe.
If we knew more about the engine maybe we could give more detailed help eh? Carb on top? CR? intake manifold style? Cubes, etc?

 

Actually it's more like my tune is ridiculously out of spec.Too much fuel makes an engine chilly. Ended up going with Delco platinum rapidfire #9's.

Those cross reference charts are like packages of socks!