440 Spark Plugs and Timing Recommendations

[Hellcat]

Hello All,

I was wondering if anyone had any recommendations for spark plugs and timing on a rebuilt 440. I figured I would go with a copper plug(but willing to listen), but the heat range is what I have in question. Should I start with the stock heat range (I believe it is 12 in the Champion world) or should I go a notch colder? As for the timing, should I put it at 10 degrees advanced at idle? I'll list what the engine has and let the conversation start. You'll notice I spent probably way too much money and maybe would have been better off going with a crate motor.....but I didn't so here I am.

1967 440 engine block bored 0.030" over
Stealth aluminum heads from 440 source
Comp Cams Ultra Pro Magnum Rocker Arms
Camshaft - Comp Cams hydraulic roller Xtreme Energy XR274HR-10 (PN 23-710-9)
-Valve springs and roller hydraulic lifters to match the cam (Comp Cams)
-Installed cam at 0 degrees, no cam advance, set it up just like the card said and it checked good
Pistons - forged aluminum flat tops (can't remember manufacturer and I don't have my engine book with me)
compression ratio calculated at 10.5:1
Carbs - six pack set up by ProMax carbs
-I had them do the work of rebuilding the carbs and they set them up on their 440 so I should have a decent baseline to work with
Edelbrock aluminum six pack intake
Transmission - A833 4 speed
rear end gears - 3.55 sure grip
Headers - old rusty set of Summit headers for break in, I think they are 1-3/4" primaries
-I have a set of Hooker ceramic coated headers ready to install once I break the engine in, (1-7/8" primaries)
Exhaust - 3" flowmaster "American Thunder" system

I also have a list of the carb settings installed by ProMax, but I don't have them with me right now. If you think that would help, let me know, and I can look those up later. If there is anything else you think would be helpful please let me know. Thanks for reading.

 

[moparleo]

So ,have you run the engine at all yet ? You didn't mention what ignition system you are using either. RJ12YC is the original plug. I would start there as a baseline. If you have access to a dyno and the motor is still on the stand, take it there for break-in and fine tuning. You need to do a break-in before you start making adjustments. After the break-in watching water temp, I would set the total timing first. That is revving the engine to at least 2500 RPM's, advancing the distributor timing until RPM's start to fall off. Then go back and set your idle speed. With a vacuum gauge, adjust the air mixture screws to give you the highest, steady vacuum readings. Reset the idle with the idle adjusting screw ( the primary butterflies). Recheck everything again and be sure to retighten the distributor hold down bolt.

 

[Hellcat]

Thanks moparleo. The ignition system is the mopar performance electronic ignition with the orange box. I have run the engine a few times in the car. The first time I ran it at 2000 RPM for around 20 minutes. I had the drain on the radiator open and was keeping it full with a garden hose, worked good...didn't overheat anyway. At 2000 RPM I set the timing to 32 degrees advance. I didn't push it until the RPM started to drop off though. I ran it down the road a few times and gave it some RPM, never cruising just up and down with acceleration so far, trying to vary RPM. Your recommendation on the spark plug is what I have followed so far. I used the RC12YC instead though, just because it has the 5/8" nut and a gasket seal since I have aluminum heads. Stock heat range though obviously. There is a chassis dyno near here, but it is $130/hr. Worth it at this stage or should I wait until I get some more miles on it?

 

[Chryco Psycho]

you may need to go hotter , the alum will pull more heat away from the plug

 

[moparleo]

The engine needs to warm up to normal operating temperature for everything to work as designed. When I said to watch the water temp, I meant just that. Just make sure that it wasn't overheating. It is normal for the engine to run hotter than normal during break in as the piston rings will generate heat while seating into the cylinders. You should change the oil and filter and if you have access to someone with a leak down tester you can see if the rings have seated. If the shop with the dyno is good, they should be able to set everything up in a short amount of time. Remember that you are paying for their experience. Just like anything else, get references from others who have used this shop.