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Mild built 383 spark plug suggestion #1810898
04/24/15 01:19 PM
04/24/15 01:19 PM
Joined: Jan 2003
Posts: 320
Dallas, TX
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71_Demon Offline OP
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71_Demon  Offline OP
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Dallas, TX
Its a 383, bored .040, flat top pistons forged crank, 10.1 compression

-stock 452 heads

- MP .474 cam

- Headers

- Dual plane intake with 750 preform carb

- MSD ignition and Mallory uni-lite distributor.

- 3" all the way back

I'm just wanting to dial it in. Strictly street car. Hasn't seen the road in years so I'm sure it will need tuning. Always ran autolites, but they fouled out real quick. I've read resistor and non resistor plugs but not sure what the differences is. Any knowledge or suggestions appreciated.


'71 Demon 383 auto '12 Ram 2500 6.7 Diesel
Re: Mild built 383 spark plug suggestion [Re: 71_Demon] #1810905
04/24/15 01:27 PM
04/24/15 01:27 PM
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usa
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lewtot184 Offline
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if your fouling something like an autolite 85 then you'll probably foul anything else out there. find out why the plugs are fouling first.

Re: Mild built 383 spark plug suggestion [Re: 71_Demon] #1810910
04/24/15 01:29 PM
04/24/15 01:29 PM
Joined: Jun 2012
Posts: 1,386
Philadelphia PA
Pynzo Offline
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Philadelphia PA
I run Champion J12YC in my 383. Non resistor with copper core. Stock plugs were J11Y and these are as close as I've ever found to them.

Re: Mild built 383 spark plug suggestion [Re: lewtot184] #1810915
04/24/15 01:33 PM
04/24/15 01:33 PM
Joined: Jan 2003
Posts: 320
Dallas, TX
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71_Demon Offline OP
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71_Demon  Offline OP
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I'm working on that. Bought a new carb with four coroner mixture screws. I had bad fuel contamination issue that I've addressed. It would plug the inlets of the carb. New fuel system from tank to carb. Just need a base line and a plug I can stick with while I get it where its good.


'71 Demon 383 auto '12 Ram 2500 6.7 Diesel
Re: Mild built 383 spark plug suggestion [Re: 71_Demon] #1810951
04/24/15 02:34 PM
04/24/15 02:34 PM
Joined: Aug 2003
Posts: 43,181
Bend,OR USA
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Cab_Burge Online work
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Bend,OR USA
What carb. brand and part number is th new one? I would start with the stock jetting and put in a new set of Autolite 85 and set the ignition timing at 34 degrees total revved up beyond 4500 RPM, once I got the timing set I would check the timing at idle RPM, if it is less than 14 BTDC I would have the distributor recurved to get between 14 and 18 BTDC at idle and no more than 34 total revved up twocents scope


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Mild built 383 spark plug suggestion [Re: Cab_Burge] #1811029
04/24/15 04:34 PM
04/24/15 04:34 PM
Joined: Jan 2003
Posts: 320
Dallas, TX
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71_Demon Offline OP
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71_Demon  Offline OP
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Originally Posted By Cab_Burge
What carb. brand and part number is th new one? I would start with the stock jetting and put in a new set of Autolite 85 and set the ignition timing at 34 degrees total revved up beyond 4500 RPM, once I got the timing set I would check the timing at idle RPM, if it is less than 14 BTDC I would have the distributor recurved to get between 14 and 18 BTDC at idle and no more than 34 total revved up twocents scope



Proform brand new, 67200.


'71 Demon 383 auto '12 Ram 2500 6.7 Diesel
Re: Mild built 383 spark plug suggestion [Re: 71_Demon] #1811100
04/24/15 07:23 PM
04/24/15 07:23 PM
Joined: Aug 2003
Posts: 43,181
Bend,OR USA
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Cab_Burge Online work
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Bend,OR USA
Originally Posted By 71_Demon
Originally Posted By Cab_Burge
What carb. brand and part number is th new one? I would start with the stock jetting and put in a new set of Autolite 85 and set the ignition timing at 34 degrees total revved up beyond 4500 RPM, once I got the timing set I would check the timing at idle RPM, if it is less than 14 BTDC I would have the distributor recurved to get between 14 and 18 BTDC at idle and no more than 34 total revved up twocents scope



Proform brand new, 67200.
I don't know or have I heard of any results on the Proform carbs, Sorry shruggy Let us know how that works out up


Mr.Cab Racing and winning with Mopars since 1964. (Old F--t, Huh)
Re: Mild built 383 spark plug suggestion [Re: 71_Demon] #1813049
04/27/15 02:25 PM
04/27/15 02:25 PM
Joined: Jan 2003
Posts: 4,721
Moved to N.E. Tennessee
GomangoCuda Offline
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Originally Posted By 71_Demon
Its a 383, bored .040, flat top pistons forged crank, 10.1 compression

-stock 452 heads

FYI, A 383 with flat top pistons and stock 452 heads will have a lot less than 10:1 compression. More like 8.5:1. The domed KB400 piston would be close to 9:1 with that head. That said, any plug with close to a stock heat range should work.


In theory, there is no difference between theory and practice. In practice, there is.
Re: Mild built 383 spark plug suggestion [Re: GomangoCuda] #1813696
04/28/15 03:56 AM
04/28/15 03:56 AM
Joined: Nov 2003
Posts: 36,040
Lincoln Nebraska
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RapidRobert Offline
Circle Track
RapidRobert  Offline
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Posts: 36,040
Lincoln Nebraska
there've been some good plug threads in the past if you can retrieve them with the general concensus that quality of most of em has deteriorated (like most else). As said I'd figure out if it is gas or oil fouling & if gas then check the choke and or the AF ratio. Timing in the ballpark. For oil, new valve stem seals (if that is it) or maybe a rebuild (read "breakin secrets" at www.mototuneusa.com


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