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360 assembly |
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Samuelsc360
AMC Apprentice Joined: Aug/19/2017 Location: Chesnee SC Status: Offline Points: 145 |
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Plastiguage says .002 which is within spec.
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1971 SC360
1973 Ambassador Sedan 360 1973 Hornet X 360 1973 Javelin AMC 401 1975 Sportabout X 258 |
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5428 |
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Sorry I didn't see this before: "The crank will turn with the rod caps torqued." So does that mean that when you install the rod and piston assembly, it does not turn? If so, check the clearance at the bottom of the piston at the crank throw. Edited by SC397 - Jan/15/2018 at 3:51pm |
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Samuelsc360
AMC Apprentice Joined: Aug/19/2017 Location: Chesnee SC Status: Offline Points: 145 |
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1971 SC360
1973 Ambassador Sedan 360 1973 Hornet X 360 1973 Javelin AMC 401 1975 Sportabout X 258 |
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SC397
AMC Addicted Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5428 |
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Was the block Line Honed, or checked for Line Bore?
At this point, I would be taking all of the parts back to the machinist and have him double check all of the clearances. Edited by SC397 - Jan/15/2018 at 4:00pm |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19610 |
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Bent crank??? If the bearing clearances are good you're running out of possibilities fast. Either a main cap is in the wrong position or the crank has a slight bend to it -- only possibilities I can think of. I understand the line-hone questions, but if it wasn't line-honed everything should go back in and turn, with proper bearing clearance. Block doesn't move, but crank can. It can have an imperceptible bend and cause things to be tight, or one or more of the mains could have been turned with a slight offset.
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Frank Swygert
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Samuelsc360
AMC Apprentice Joined: Aug/19/2017 Location: Chesnee SC Status: Offline Points: 145 |
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I've been in touch with the machinist. He said it was checked for alignment and found no issues. He also suggested that I have it align honed if I didn't get it figured out.
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1971 SC360
1973 Ambassador Sedan 360 1973 Hornet X 360 1973 Javelin AMC 401 1975 Sportabout X 258 |
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Lyle
AMC Addicted Joined: Jul/17/2014 Location: None Status: Offline Points: 772 |
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Try to identify the offender:
Take the pistons out and install #1 and #5 main bearings, using plastigage to ensure clearance spec and then lube, re-torque to 75%. Rotate the crankshaft and ensure it runs free. Install #2, #3, #4 one at a time the same way and repeat. If all is good it's not the crankshaft. Install the 2 pistons and rods on their respective journals and repeat the same procedure until you find the bind. Tedious but cheaper then paying someone else to go through this. Honing at this stage is a shot in the dark in my opinion. It could be one bearing tab not seating for all you know at this point.
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Samuelsc360
AMC Apprentice Joined: Aug/19/2017 Location: Chesnee SC Status: Offline Points: 145 |
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Excellent advice. Will try that next.
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1971 SC360
1973 Ambassador Sedan 360 1973 Hornet X 360 1973 Javelin AMC 401 1975 Sportabout X 258 |
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Samuelsc360
AMC Apprentice Joined: Aug/19/2017 Location: Chesnee SC Status: Offline Points: 145 |
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OK. I took the rods out and took the main caps off. I put the mains back on individually in random order. I torqued each one as I put it on to 75%. #5 was the first. Crank won't turn at all at 75% torque. Loosened it back up and put on the remaining caps in random order torqueing individually at 75%. The crank turned ,as each one was tightened. At the end the 1 through 4 are tightened to 75% the crank turns. When #5 is tightened it doesn't turn. When I torque #1 to 100lbs, the crank doesn't turn. I appears the 3 center ones are OK.
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1971 SC360
1973 Ambassador Sedan 360 1973 Hornet X 360 1973 Javelin AMC 401 1975 Sportabout X 258 |
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Lyle
AMC Addicted Joined: Jul/17/2014 Location: None Status: Offline Points: 772 |
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Did you check #1 and #5 with the plasigage? If you did and the clearance is good, then there is a problem with the crankshaft straightness. If the clearance is not good then the crankshaft was machined wrong or the bearings are out of spec. The block should be the last concern if this is a rebuild and it ran fine before. My bet is they dropped the crankshaft if clearances are good.
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