Spark plugs
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Instructor
Joined: Feb 2022
Posts: 203
Likes: 10
Spark plugs
I have a 406 10-1 compression afr head’s Holly carb 770cfm. Running ac 41-628 plugs.they run rich black no matter what I do.what plugs are you running.do I need to go hotter on the plugs.if so what is the number.
Pro
Joined: Sep 2022
Posts: 553
Likes: 151
had the same problem on my 10.5 :1 Merlin 540.... so i installed a AFR gauge . ( Innovate ) Then you see at least what's happening.
Running to rich , i overhauled the carbs ( tripower here ) with new gaskets and power valve., AFR is fine now , idle around 15 , driving 12...13
And new plug wires , measured them at 15 K Ohm... new MSD set is at 150 Ohm ! Was a big improvement in driving. Must have given "weak" ignition . ( had already new HEI distributor)
I use Accel 6 plugs , don't know what's the heat range compared your AC plugs. But must test drive it more to see if they are not to "hot" plugs.
Running to rich , i overhauled the carbs ( tripower here ) with new gaskets and power valve., AFR is fine now , idle around 15 , driving 12...13
And new plug wires , measured them at 15 K Ohm... new MSD set is at 150 Ohm ! Was a big improvement in driving. Must have given "weak" ignition . ( had already new HEI distributor)
I use Accel 6 plugs , don't know what's the heat range compared your AC plugs. But must test drive it more to see if they are not to "hot" plugs.
Drifting
Joined: Sep 2009
Posts: 1,824
Likes: 545
From: Langhorne, Pa.
Thought I knew a little about reading spark plugs:-).. man did this video open my eye’s..
* Interesting on how to read/get timing info off of the ground strap on the spark plug*
https://garage.grumpysperformance.co...ng-plugs.5428/
(Steve Morris has some very interesting video’s)
Good Luck
Chalie
* Interesting on how to read/get timing info off of the ground strap on the spark plug*
https://garage.grumpysperformance.co...ng-plugs.5428/
(Steve Morris has some very interesting video’s)
Good Luck
Chalie
