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torque plates/ honing plates |
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White70JavelinSST
Supporter of TheAMCForum Joined: Aug/08/2012 Location: Minnesota Status: Offline Points: 4867 |
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As stated a few posts back, Matt at Bulltear makes sells, and rents out bore/hone plates for AMC check it out here. http://www.bulltear.com/catalog/index.php?cPath=21 |
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70 Javelin SST, second owner, purchased 1972
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amxess
AMC Addicted Joined: Aug/30/2007 Location: Florida Status: Offline Points: 765 |
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I'm south, SE Florida though. Have some original torque plates. Heavy though.
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4741 |
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I hope 69ambassador390 comments. He and I compared the bores of a 390 with and without a torque plate bolted to the block, and were able to measure a couple tenths of a thousandth of distortion in the top inch or so of the bores. I don't remember the exact number, but I know it was less than .0005" distortion and it was only at the very top of the bores. Whether that is significant or not is up to you. Keep in mind that bores probably shift around more than that from heat while the engine is running.
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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shadowmask70
AMC Apprentice Joined: Dec/01/2010 Location: Langley BC Status: Offline Points: 59 |
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Interesting reading some of the replies. Never measured with/without myself. Bought plate from BHJ a while back. Hoping all those little things add up. At least I'm not tossing and turning at night wondering if my walls are distorted? (and I would otherwise haha)
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gd5052
AMC Apprentice Joined: Jun/16/2011 Location: Illinois Status: Offline Points: 108 |
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Why not build it as precise as you can with plate.
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5428 |
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Don't worry about using a honing plate. I have never used one even on a high performance engine. Worry more about cylinder tapper and If they actually honed deep enough. I have had issues with both on engines that weren't machined at the place I go to. |
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4741 |
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It feels good to be as precise as possible, but at some point you are just picking fly poop out of pepper. In other words, it doesn't matter. There are so many things that cause cylinder which were honed perfectly straight to distort once the engine is assembled. Not just assembled, but running; thermal expansion, torque output.... Honing with a torque plate eliminates one source of cylinder distortion, but what if the distortion caused by the head bolt torque helps offset other distortion? For instance, what if the head bolt torque causes a -.0002" distortion but thermal expansion of the running engine causes a +.0002" distortion? The net result is zero. The distortion caused by the head bolt torque is actually beneficial in that case. On the other hand, the head bolt distortion could add to the thermal distortion (+.0002" plus another +.0002"). Then torque plate honing would be beneficial. We just don't know. We're also talking about less than .0005" of bore distortion at the very top of the cylinders. It's in the top inch of the cylinder. That is up in the ring land area where the piston to cylinder clearance is like .030"! We're worrying about 1/60th of that clearance in distortion caused by the head bolt torque? Only the piston rings are affected that high up in the cylinder. Slight distortions in the cylinder that high up could reduce ring seal by a small amount, but not nearly as much as ring end gap and land clearance. This is all theory and I get accused of talking in too much book theory and not enough personal experience, so here is some personal experience for you: I had to pull the cylinder head off my 232 only 15,000 miles after I rebuilt it because of valve trouble. I gave it a 400-grit plateau hone (without torque plate) when I rebuilt it, so I was able to see how the cylinders looked after 15,000 miles. The cylinders had almost entirely no crosshatch left and had turned smooth as glass except for some areas at the very top of the cylinders, near head bolts. These were areas that the head bolt torque distorted the cylinder walls into low areas that the piston rings could not reach as well and did not wipe out as much of the crosshatching. The rings still contacted these areas, but did not wear them away as much as they did other areas. Essentially, the crosshatch acted as a guide coat and the rings "block sanded" the guide coat to reveal high and low spots. I measured the cylinders with a dial bore gauge, of course without a head or torque plate attached. They were not perfectly round. The crosshatched "low spots" actually measured higher than the rest of the cylinder, which was smooth. That seems like a contradiction, but think about what happened: 1. The cylinders were honed perfect straight without head bolt torque. 2. The head was torqued on, distorting some areas at the top of the cylinders into recessed areas. 3. The piston rings wore very little in the recessed areas caused by head bolt torque, and wore more in the rest of the cylinder. 4. The rest of the cylinder slowly wore down (broke in) to match the recessed areas, which retained more of their crosshatching because there was lower "break in" wear there. 5. Result: perfectly straight cylinders even with the head bolt torque because the cylinders "broke in" straight. This possibly happens with other kinds of bore distortions. An engine that is mostly run at highway speeds will have certain bore distortions based on the heat and load encountered. The piston rings will "block sand" the cylinders straight for that condition, which means in any other condition (such as when the engine is cold) the cylinders will be distorted. Keep in mind that we are talking in tenths of a thousandth of an inch here. Very minor, but it is there and measurable...barely. This also isn't to say that the piston rings don't eventually cause cylinder distortion of their own. They will eventually wear the cylinder to a barrel shape, but they do help scrub out other irregularities such as head bolt distortion. It is my philosophy that bore distortion caused by not using a torque plate when honing will quickly be wiped out by the break-in process.
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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Photon440
AMC Nut Joined: Sep/22/2014 Location: B.C. Canada Status: Offline Points: 327 |
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They're not inexpensive, that's for sure.
http://honingplates.com/index.php?main_page=product_info&products_id=18%22%22 |
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Faster is Better
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6PakBee
Supporter of TheAMCForum Charter Member Joined: Jul/01/2007 Location: North Dakota Status: Offline Points: 5454 |
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This is like a lot of things in life, it depends. I seem to remember reading that if you bore a SBC without a plate and then bolt one on, a new piston ring in the bore won't touch the wall in some spots. From some of the comments from forum members with much experience, the later AMC V8 doesn't seem to behave like this. So again, it depends.
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Roger Gazur
1969 'B' Scheme SC/Rambler 1970 RWB 4-spd Machine 1970 Sonic Silver auto AMX All project cars. Forum Cockroach |
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amx409
Supporter of TheAMCForum Joined: Dec/02/2007 Location: New York Status: Offline Points: 195 |
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Is anyone willing to rent out their plate?
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