LM7 5.3 New rings hard to turn over
02-23-2011, 12:35 PM
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LM7 5.3 New rings hard to turn over Hey, this might be just in my head. I have a LM7 5.3 that had over 150k on the clock. I bought it from a junkyard, the poor thing was obviously not taken care of well. I ended up disassembling the entire motor, had it hot-tanked and the cyl's de-glazed. Installed new main bearings (and coated them liberally with some engine assembly lube), torqued down the mains to factory specs (gm replacement bolts). Spins nice and freely, not caught anywhere. Next I had my pistons cleaned and ensured the ring lands where nice and clean before installing my new hasting rings;
Bore size: 3.780" (96.00 mm)
Compression Ring: 1.5mm
Compression Ring: 1.5mm
Oil Ring: 3.0 mm
Got them installed and clocked according to my ls1 book. They compressed just fine in my ring compressor. I cleaned my bores with some acetone and then coated them with a layer of 5w-30. They installed just fine with a few nice taps of the rubber hammer, and I could push them in the rest of the way with my hand. These are the stock rods and pistons, never taken apart from each other. I installed new rod bearings (with assembly lube as well) and finished installing all of the pistons with the dot on the piston top facing the front of the engine. With two pistons installed I started to notice it was kinda hard to turn over. I figured it was just the new rings and continued on. Now with all of them in it's hard to turn over. I grab the crank counter-weights and have to put probably 30-35lbs of force of them to get it to move a little. I then decided the bores probably need some more oil. I flipped the motor over so I'm looking at the piston tops and added some oil to every cyl and let them sit for awhile. Still takes 30-35lbs to get it turning over.
Is this normal after new rings? I should note this is my first time replacing rings. I've done a few bottom end rebuilds on old 350's and LT1's before but never an "LS" based engine. Any help/comments would be greatly appreciated. Thanks for reading my novel!
Bore size: 3.780" (96.00 mm)
Compression Ring: 1.5mm
Compression Ring: 1.5mm
Oil Ring: 3.0 mm
Got them installed and clocked according to my ls1 book. They compressed just fine in my ring compressor. I cleaned my bores with some acetone and then coated them with a layer of 5w-30. They installed just fine with a few nice taps of the rubber hammer, and I could push them in the rest of the way with my hand. These are the stock rods and pistons, never taken apart from each other. I installed new rod bearings (with assembly lube as well) and finished installing all of the pistons with the dot on the piston top facing the front of the engine. With two pistons installed I started to notice it was kinda hard to turn over. I figured it was just the new rings and continued on. Now with all of them in it's hard to turn over. I grab the crank counter-weights and have to put probably 30-35lbs of force of them to get it to move a little. I then decided the bores probably need some more oil. I flipped the motor over so I'm looking at the piston tops and added some oil to every cyl and let them sit for awhile. Still takes 30-35lbs to get it turning over.
Is this normal after new rings? I should note this is my first time replacing rings. I've done a few bottom end rebuilds on old 350's and LT1's before but never an "LS" based engine. Any help/comments would be greatly appreciated. Thanks for reading my novel!
02-23-2011, 01:20 PM
#2
Are you trying to turn the engine over buy turning the weights or using a ratchet on the front of the crankshaft?
Any new engine is going to be harder to spin over than one that's broken in. Did you check to make sure none of the wrist pins where tight when you put it together?
This sounds normal to me, but saying its hard to turn over is tough to convey over the internet.
Did it get harder and harder to turn over with the more pistons you installed? I would guess probably yes. There is a lot of friction in the cylinders now with the honed cylinder walls and new rings.
Any new engine is going to be harder to spin over than one that's broken in. Did you check to make sure none of the wrist pins where tight when you put it together?
This sounds normal to me, but saying its hard to turn over is tough to convey over the internet.
Did it get harder and harder to turn over with the more pistons you installed? I would guess probably yes. There is a lot of friction in the cylinders now with the honed cylinder walls and new rings.
02-23-2011, 01:26 PM
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I have been turning it by the counter-weights. All wrist pins were nice and free. I cleaned them all and dipped the pistons into a bucket of oil for 5mins each prior to install to ensure the pins were well lubed. Yes, it got harder after every piston. I understand it's hard to convey as well. I've just never replaced rings before so I'm not sure what to expect. I've turned over a fair share of broken in 350's and etc. Just never a fresh one.
02-23-2011, 05:34 PM
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An old guideline I once read and used when building SBC's was a good tight engine will require around 40-45 #/ft torque to rotate the crank on the engine stand with the heads on and the valve lash set with normal valvesprings - usually took about 20-25 #/ft for just the shortblock.
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