Thread starter twstd50; Start date Sep 28, 2004; Forums. Generally the low compression heads have a 18mm plug thread and the higher compression heads have 14mm spark plug threads. Oct 20, 2003 97 0 6. Mercury Corrosion Inhibitors & Grease. When the two piece C4 plug was discontinued the W18 was the replacement. I tried some screaming Eagle plugs but they didn't last very long and once the gap opened up a small amount it run like crap. .040 gap the plug that harley recommends the wire that harley recommends the torque you service manual call for Must follow steps. Not all plug manufacturers follow the same guidelines. Like I said before as well. Those with modified engines must remember that higher compression or forced induction will typically require a smaller gap setting (to ensure ignitability under higher pressure). Spark plug gap for Points is .035 and any electronic or MSD is .040-.045 General Guideline- Pump gas street engines would use a -5 to -7 heat range, high compression race engines may use a -8 or -9 heat range, and boosted/nitrous engines may use a -9 or -10 heat range depending on levels of boost/nitrous. The temperature of the end of the plug's firing end must be kept low enough to prevent pre-ignition, but high enough to prevent fouling. I have several NOS C4 plugs and this is the recommendation included with each plug. The 18mm plugs, on low compression heads, call for 0.028"-0.032" gap. Spark plug specifications, which include type, heat range and gap, will be found in the owner's repair manual. Slight misfires can cause a loss of performance for obvious reasons (if fuel is not lit, no energy is being created) 1979 - 1995 (Fox, SN95.0, & 2.3L) -General/Talk-1994 - 1995 Specific Tech . You will never need to index new plugs in your heads again. What spark plugs do you use? Spark Plug Specifications. Autolite® Racing Hi-Performance Spark Plugs. 7 posts • Page 1 of 1. lluciano77 Member Posts: 177 Joined: Fri May 09, 2008 12:34 pm Location: High compression SBC 400 spark plug recommendation. Spark Plug Info **Note: Heat ranges are determined by NGK standards. I’ve been wondering if I should lower the gap on my TFS head 11:1 compression motor. Come check out all the different pictures and details about your spark plug gap and so much more. This is why even on high energy ignition systems, (CONTRARY to what their lame instructions say to gap your plugs at), you CLOSE the gap on engines making more power. Insufficient spark plug gap can cause pre-ignition, detonation, even engine damage. Gapped 35-40.The ION sensing works with any of the ones you mentioned.Venture off to other brands of plugs /wires and your gambling . and xulfiqar bhai could you please suggest me the best spark plugs for honda city idsi 2004 which would give my car enough power, acceleration and fuel economy, currently Im using its genuine spark plug purchased from honda show room with having gap 0.08 mm for cng Please consult with head mfg. High compression SBC 400 spark plug recommendation. We have an extensive range of spark plugs, each with their own unique characteristics specifically engineered to its vehicle application and they are designed to suit a broad range of vehicles on Australian roads. Actual racing spark plug used by many professional car drivers. A spark plug can deliver a weak spark (or no spark at all) for a variety of reasons…defective coil, too much compression with incorrect plug gap, dry fouled or wet fouled spark plugs, insufficient ignition timing, etc. Dry fouled or wet fouled spark plugs, insufficient ignition timing. Very cold running plugs are undesirable … LT1 Thread – 14mm Reach - .708” Socket – 5/8 hex Seat - Taper Stock Heat Range: 5 Gap: .050 Plug: NGK … ***Note: List is intended for reference only. Mild engine. A high voltage spark jumps the gap, producing ignition fire. Hey I tried doing a search, and I read the how-to by mike_sho on this, but I was wondering what are the spark plugs I can get for my lude? Spark plug gap does affect combustion, power used to create the spark, length of spark, and other things. Moderator: Team. Shop Recommended Products. General engine tech -- Drag Racing to Circle Track. 948 posts ... After selling the mid engined polo I have bought a 69 Camaro drag car runing a high compression … And ION sensing works with them. You will be fine with just a Standard HD spark plug . The high compression heads, with the 14mm plugs, call for 0.023"-0.027" gaps on a Z. Original Poster . "Indexing" your spark plugs is the practice of making sure your ground strap is opposite of the dome of high compression pistons. Spark plug indications for correct heat range Spark plug condition: Normal - Correct plug … • BRISK Turbo racing spark plugs machined electrode design provides a fixed gap setting which greatly increases the spark plug durability, and protects the spark from high turbulence changes in the air. It was thought that the higher compression would blow out the spark and a closer gap of .032 was recommended with the C4 plugs. any good spark plugs and what gap do you start with for 383 stroker: thanx, scott Jul 29, 2008 #2. The process of clocking the electrode gap towards the piston helps ignition under high pressure. NGK Spark Plugs. on high performance builds that get the plug checked and changed alot i run .040 on most stock stuff i run .038 to give the gap some extra wear for those who do not change there plugs at 10,000 miles i would think any where in the .037 to .040 would be just fine with high compression the wider the gap the more energy the spark generated to a point From that, they can make a recommendation as to what spark gap should provide the best combination of ignition reliability and spark plug longevity. When the Spark Plug Gap remains larger under a boosted application, a Misfire can result due to the spark being blown out Fox V8 Mustangs were equipped with ASF or AWSF spark plugs. Spark plug torque is very important. marT350T. Discussion Starter • #1 • 1 mo ago. Remember that, and go by the service manual. Sep 28, 2004 #1 I'm having a misfire at around 6100 rpms and I think my spark plug gaps may be wrong. and ignition mfg. T. twstd50 Member. My daily work tractor … Off the bottle, ran good way past 5,500 rpms, on the bottle, stopped at 5,500. Usually .035" is around the best gap, even though many instruction manuals say to open your gap to .045". A spark plug can deliver a weak spark (or no spark at all) for a variety of reasons. Read all about it and the great details in this special web exclusive for Circle Track Magazine! From 1982 to 1985, the High Output (H.O.) for proper gap. Been out of the loop for a while. Thanks for everyones time. Spark plugs that are not gapped properly will cause the engine to either skip firing, or ignite too soon in the compression stroke. NGK Spark Plugs. I would go with 0.038 because if you get too wide of a gap spark may not jump up far. NGK have over 80 years of experience in spark plug manufacturing and we are a world leader in spark plug technology. DAWG ... 383 are high compressions (usually) which means more heat so you will want to run a cooler plug so you don't have detonation, as for the gap i would say go with stock gap or a bit more Jul 29, 2008 #4. dustypowers Veteran Member Lifetime Gold Member. A ‘cold’ plug on the other hand, transfers heat rapidly from the firing end and is used to avoid overheating, where the temperatures are high in, say, a high compression ‘race’ engines. (ION sensing working correct) The v rod plug is another cold plug that runs good in high compression. Properly gapped spark plugs also remove heat from the cylinder ignition chamber. " Re: high compression relative to spark plug gap? Defective coil, too much compression with incorrect plug gap. Have NGK TR6’s gapped at .054. Discussion. Found that the C4 or W18 run very clean in my Model A, high compression head or not. Been like this for years but would I benefit to close it to say .045? Once we find a plug/cylinder index match, we log it with this Allstar Performance tool. Compression ratio is 9.50:1, to help with the nitrous. While plugs are pre-gapped from the factory, the gap may need to be adjusted for the vehicle that the spark plug is intended for. Spark plug manufacturers use high-pressure test stands to simulate engine running conditions so they can evaluate spark plug performance under various operating conditions. 2,098 Posts . Mercury engines come from the factory with the correct heat-range spark plug for your application, and PartsVu carries a wide assortment of these OEM plugs. 07-22-02 05:52 AM - Post# 115972 In response to 383 with nitruos, set up in older Datsun pickup for drag racing only. spark plug gap on a 10:1 compression engine. It is important, and a big deal. BBC or SBC Discussion in 'Engine ... On my hot rod street car it has a slightly too high compression with factory iron heads,and I run cheap Delco R45T's with a stock points distributor,Crane electronic conversion,Crane coil and low resistance wires. Reply Reply Author. What should they be gapped to on a 331 stroker with … Heat range indicates the length of time needed for heat to be drawn away from the plug tip. I get my NGKs at 0.034 but that is because of my turbo when it puts out 8 pounds of boost at full throttle the compression ratio is over 13.5 to one. Mustang Forums. Too much gap can result in a higher rate of misfires, noticeable loss of power, plug fouling, and poor economy. Slight misfires can cause a loss of performance for obvious reasons. This paper shows that spark plugs only one range colder should be used when converting from gasoline to LP-gas operation. Post by lluciano77 » Mon Oct 14, 2013 11:37 pm. The Mercury spark plugs and compression 100-hour service step begins by removing any plastic covers covering your spark plugs or ignition coils. ****Note: NGK IX and Denso plugs are Iridium. Provides cut back ground electrode, anti-corrosive nickel plating and large ground electrode for better heat transfer. Proper spark plug gap with MSD 6a Don't know it this is the right forum, but my question is: I have built a 200 Ford I6, cam etc., using a 6A box, blaster coil, built DuraSpark and using Autolite AP 46 plugs. version of the 5.0L used one heat range colder. BBC spark plug gap. Unfortunately the plug gap is mainly determined by the output of the ignition. What would be the best gap for this engine, I have heard everything from .50 to .65 right now they are set at .55. I need to change my spark plugs… You get too wide of a gap spark may not jump up.!, detonation, even though many instruction manuals say to open your gap.045. 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