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#1
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Spark plug heat range?
I'm fishing for some input on what heat range, gap and brand/type of spark plug works well with the Jacob's Pro Street unit and coil.
I plan on using Taylor spiro Pro 8.1mm wires with the Mopar Performance tan cap and rotor that have the brass conductors. Does anyone have the wiring schematics for bypassing the Chrysler ECU? I was also wondering how bypassing the Chrysler ECU would affect the cruise control (because the cruise control vehicles have a different ECU). Thanks for the info! |
#2
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Bypassing the ECU wont have any effect on the cruise. The cruise controls are not connected to any ingnition systems. Any plug will work, except for those gimmick plugs with V and U shaped ground straps and platnum and such. Here's the correct way to find the plug gap. Start at .040 and open it up by five till it developes a high speed miss. Then back the gap off by 2 until it is gone. Heat range depends on whats in the engine, and how you drive it. Stock plug is a Champion and that's what we use even in our race cars. They work great. The only problem you will ever find with a plug is getting the heat range correct. No such thing as a bad plug, so just pick a name and get the heat range correct and leave the gimmick plugs alone.
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#3
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http://www.jegs.com/cgi-bin/ncommerc...20&prmenbr=361 If this is what your looking to by pass. I just took the leads off the ballast and ran a connector wire to the leads. So now the ballast and the Ignition Control Units is no longer hooked up.
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#4
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Why do vehicles that have cruise control call for a different ignition ECU? I know that the module is not connected to the cruise control unit, but why would they make a different ignition module specificly for the vehicles that have cruise control?
Wouldn't eliminating the ballast resistor fry somethng? I still don't understand the correct way to bypass the module. I understand that the original Chrysler ignition module sends irratic signals to the distributor and can disrupt it's phazing. This is why some people bypass the unit with the Jacobs unit, but why would you eliminate the ballast resistor? |
#5
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I eliminated just so see what would happen. I am running an msd ignition so I just wanted see if would give me a little more. It seem to a little bit but I noticed the biggest difference when I disconnected the vac advance
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#6
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Quote:
As far as heat range goes, start with the stock range and work it cooler. You should not need to go more than 2 steps cooler on your engine. Even if it's a power unit. TrashedChargers quotes; Quote:
Quote:
Quote:
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#7
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The Jacobs doesn't require the ballast resistor. All you need for the Jacobs is to connect the distributor to trigger the ignition. You can leave the old system in as a backup, but I have never needed to use the old system.
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#8
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Quote:
TrashedChargers quotes; It is possible that the spark is stronger/hotter from the box. Then again, I never noticed what you have.[/QUOTE] Correct again. A little more dwell and timming to make up for the vacuum motor tugging at your carb. |
#9
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BTW: I use Autolites with .055 gap and went two ranges colder to work the best for me. Not a terribly wild build but certainly a hotter street engine than stock. As they say, your mileage may vary. Biggest difference was triggering directly from the dist and not the orance box.
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#10
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How do you know what is colder or hotter? Do all plug manufacturers use a standard for heat range? When do you know which way to go in determinming heat range?
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#11
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Each plug manf. uses its own means of id for heat range and such. The standard Mopar 318 plug was a Champion RN12YC . R = resistor, N = 3/8 reach, 12 is the heat range, Y is an extened tip, and C = a copper core. If using a Champion plug and you want a colder one go to a N7YC. Race plugs use a different number for Champions though and they are a little shorter too. Most hp engines will require a colder plug. If it idles a lot, use the extended tip to help from fouling the plugs with fuel and deposits. Read the plugs to see if you need a colder one or not.
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#12
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Ok, should I try a colder plug??
I have a 440 w/ Holley 750 Vac. secondaries, Comp Cams Xtreme Energy split duration Cam .477/.480 lift, 268/280 duration, Weiand Action Plus dual plane manifold, MSD Digital-6, MSD Pro-Billet distributor, Hooker Headers, etc. The problem I am having is the car runs rich (black smoke and exhaust smell) but performs well. Throttle response is crisp, no bogging, and solid the whole way through the powerband. I don't want to start rejetting and ruin this car that starts instantly, runs great...but just stinks a little, heh heh. 1966 Plymouth Satellite went 14.00 at 102mph (some tire spin), has 2.94 non-posi rear, 727 w/Cheetah manual valve body, has full interior and such, so I gather its in the upper 3000lb range. To me, with that rear, that e.t. seems just about right? Any thoughts???? |
#13
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Just for the record, the "N" series plug in a Champion is 3/4" reach. All Champions get colder as the number gets smaller. In the stock type plugs a 17 is usually the hottest and a 2 is cold. In the racing plugs a 65 is the hottest and 53 is cold. And generally, a 2 is about a 65 when going from a stock plug heat range to a racing heat range.
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#14
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I like the racing plug tho, unlike a 2, it has a big ol tip and is a heat builder. I run c 61's in my race car and they seem about right, and they have a smaller electrode, so it fires easier, less resistance. They of course where out faster, so they say, but I do have 100 some race nights on one set and they still look good.
Autolites are a bad plug to read as they are black coated, unlike a champion, which are silver, and when they get hot they discolor down the threads, so for me it is champions all the way. 55 gap, wow that sounds high, does it idle rough? |
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