I'm in the process of building a 383 for my Duster, i'd like to bump up to Platinum or even double platinum plugs for it but i'm having trouble locating them or even finding part numbers.
I'd like to stick to champion's if i can. Can anybody help with part numbers?

Get a set of NGKs and be done with it.No need for fancy plugs.I run them in my 440 with 12.5 pistons on the street.Have them in the kids 413 also.Tried Champion and Autolite race plugs.The NGKs are way better.Rocky

I've had great luck with NGK's also. They stay cleaner than the others and keep working. Nominal life of a standard plug is what... 30k? You will probably be changing them first for some other reason so little benefit for platinum.

What Rock said, k.i.s.s. I ain't used NGK's but I've read (on here) nothing but good reviews on them. trick plugs are snake oil however trimming back the ground electrode but you keep enough bend so you can adj the gap(which unshrouds the flame kernel)/clocking the gap (there's a name for that)/experimenting with different gaps does work & the only trick I would consider trying is filing the center electrode to a point (that would drastically reduce their life but power is power). At the very least you want all edges sharp/not rounded (reduces arc over required voltage which is critical at higher RPM's when there's less time for coil saturation). Grab a point file (if you're old enough to know what they are ). To (really) kiss, NGK plugs gapped at .035" & regularly file the electode edges to keep em sharp, a little antisieze on the threads

RR I have at least 4 points files.Just used one about a month ago to file the points in my J Deere lawn tractor.Rocky

Rock I've always known we were (are) kindred spirits. I never forgot way back when the one guy got offended at you calling you kids kids. I used to be a goat farmer & a "kid" is a young goat & I wanted to tell him that my kids are my goats & my goats were my kids & I wanted to post that so bad (since it was true) but that would only have aggravated him (further) which is not what what I generally like to do unless I'm the person being messed with. I gotta go get some breakfast (& some coffee)

Hey RR I still have a SnapOn meter for points and dwell etc.Got it for 2 bucks from my brother at a garage sale.He just gave me a new analog Ohm/Volt meter also.Still in the box.It cost him a buck.I remember using them to read codes on the early computer car.Count the meter sweeps.LOL.Ill bet over 1/2 of the guys here never heard of that.I also have 2 sets of the adjusters for setting GM points where you opened the door and turned the screw.Been many years since Ive used it though.Rocky

NGK copper or Platinum? All i ever used in my cars have been Champions never tryed anything else.

I got the race plugs for my aluminum heads.They were under 15 bucks for a set with shop discount.The 62 is sleeping or Id pull one and see what number the kids iron heads are.Rocky

We really need to know what type of heads, stock or aluminum aftermarket heads, compression ratio, type of fuel to be used and whatever else you want to share

It would be nice to have a chart to go by. There really doesn't seem to be too many plug options for the big blocks.

I used to drag race motorcycles, and at that time Champion made a plug that was quite a bit better than NGKs. It was a N2G, I think the G stood for gold, and it had a fine wire electrode.Worked great on the street also, but as I said they don't make it anymore. Just something to chew on.

I would highly recommend to use standard NGK plugs in a 383 and not platinum or iridium plugs. Save yourself some money and heartache.

Standard plugs will last longer in our old engines. Those others are more designed for fuel injection where the motors run much cleaner, imo.

I found out the hard way years ago after spending some money and time to find out. My

I just remembered that 383 uses the short reach plug, that might be why you can't find a part number for platinum plug? Might not make them in short thread?
I was using the 3/4 long reach plugs when I did my real world testing.

NGK part no 3332.Not hard to find.Rocky

you didn't happen to race at Cherokee did ya?

Hello About spark plugs ,in our race cars and street cars we all run autolites , 86 in a hot motor and 85 in a cold motor , hot motor would be a race engine ,a cold motor is a street engine , never had any trouble. ( a real Mopar man)

Yes, I did race at Rogersville, first person in East Tennessee to run Nitrous in 81, and on a motorcycle.