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By Ted - 12 Years Ago
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This is for Marv. I’m having trouble with the private messaging so I’m posting the answer to your question here. By the book and for aluminum heads, 8-12 lbs/ft torque for spark plug tightening. Be sure to use anti-seize on the threads.
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By marvh - 12 Years Ago
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Thanks Ted.
marv
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By Ted - 12 Years Ago
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Charlie sent me this link to a NGK technical bulletin. It’s worth reading in regards to spark plug plating and the use of anti-seize with certain spark plugs. http://www.ngksparkplugs.com/pdf/TB-0630111antisieze.pdf
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By Ted - 12 Years Ago
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In looking at the AFR instructions for their heads, they do not recommend using torque wrenches on the aluminum heads when installing the spark plugs. Here’s the exact text from their instructions: Intake, exhaust bolts, and spark plugs: We suggest not using a torque wrench on these locations as commonly inaccurate torque wrench values can easily strip the smaller threads. Just snug up hand tight with a wrench only.
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By pegleg - 12 Years Ago
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Which is exactly why many of the early Detroit aluminum heads used "threadserts." The much larger od threads would stand a lot more torque on the bolts and the steel threadserts could handle repetitive use.
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By charliemccraney - 12 Years Ago
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Then the only problem is what is "hand tight." A guy my size probably couldn't do any damage but what about someone 50 - 100lbs bigger?
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By aussiebill - 12 Years Ago
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charliemccraney (6/2/2012)
Then the only problem is what is "hand tight." A guy my size probably couldn't do any damage but what about someone 50 - 100lbs bigger?Charlie, bit like thinking about how hard do you squeeze an egg, like anything there is a feel related tension, tighten to light nip then tighten slowly till you feel it get harder, not keep going indefinitly, then another nip and should do it, its not in tension like a bolt and nut, i would never use a tension wrench on any bolts under 3/8", thats my take on it. 
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By MoonShadow - 12 Years Ago
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I use a 3/8" ratchet and hold it by the head instead of the handle. Works on intakes, spark plugs etc.. Works for me! Chuck
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By charliemccraney - 12 Years Ago
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But that's the problem, Bill, you have to break a few eggs before you get the feel for how tight you can hold one. Hand tight doesn't give any kind of reference for someone without experience. At least with a clicker wrench there is some reference. I'd hate to be the guy who stripped my bran new heads because I got them what I thought was hand tight. It's open to interpretation, and that is where I see an issue. Not everyone who tackles the job will have years of experience and know the feel or have developed a method.
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By aussiebill - 12 Years Ago
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charliemccraney (6/2/2012)
But that's the problem, Bill, you have to break a few eggs before you get the feel for how tight you can hold one. Hand tight doesn't give any kind of reference for someone without experience. At least with a clicker wrench there is some reference. I'd hate to be the guy who stripped my bran new heads because I got them what I thought was hand tight. It's open to interpretation, and that is where I see an issue. Not everyone who tackles the job will have years of experience and know the feel or have developed a method.Charlie, you,re exactley right on all points, does require some expeirence, i would just assume most car guys have some feel for tightness. We,re into autumn fall here, raining and miserable. best regards bill.
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By MoonShadow - 12 Years Ago
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Gripping the head of the 3/8th ratchet severily limits the amount of tourque anyone can put on a bolt. I end up at 20 to 30lbs. Check one and see what you can do. Chuck
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By Ted - 12 Years Ago
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So there you have it. Torque wrench or not for the spark plugs in aluminum heads? I’m sure that AFR has had issues with stripped spark plugs and not using a torque wrench was their fix for the problem. I can see where using a ft/lb torque wrench that starts at 20 ft/lb on the scale would be an issue. Using an inch pound 3/8” drive torque wrench would definitely add an extra level of accuracy but the majority of back yarders out there simply have a ½” drive torque wrench with at least an 18” handle that has the potential of over-tightening in the lower torque bands. Tightening anything in aluminum just compounds issues with stripped threads.
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By PF Arcand - 12 Years Ago
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I'm with Chuck on handling small bolts or tightening into aluminum. Hold the wrench near the head, not on the full handle.. On really small stuff, just use the wrench with your fingers.
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By pegleg - 12 Years Ago
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Watch using "Never-Sieze" on plugs. Too much will turn to carbon and you will remove the threads along with the plug.
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By Terry Flannery - 12 Years Ago
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Don't intend to hi-jack this thread but what is the best plug for a y-block, 292 heavy duty truck engine with a 2-4 set up and it is not burning all the gas, plugs are black. Right now have a set of AC in it.
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By Ted - 12 Years Ago
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Terry Flannery (7/26/2012)
Don't intend to hi-jack this thread but what is the best plug for a y-block, 292 heavy duty truck engine with a 2-4 set up and it is not burning all the gas, plugs are black. Right now have a set of AC in it.Terry. I’m assuming you posted this in the aluminum head section because you have aluminum heads. If so, then the Autolite 3924’s would be a good start. If you have iron heads (18mm tapered seat), then the Autolite 46’s would be a good starting point on a low compression engine. If your AC plugs cross-over to the same number as either of these, then you potentially have too rich a fuel mixture at idle and/or at low speed which will be difficult to correct even with hotter spark plugs. If you continue to have issues around this, feel free to start a new post in the technical section where it will get more traffic and also be more specific to your problem.
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