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#101
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How can spun bearings lock it up?
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#102
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Now that you have the heads off, can you post a picture of the head gaskets in place on the block? I am curious if the thin spot of the fel-pros pushed into the water passages (detonation)
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#103
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old habits die hard
spun bearing = old school blanket coverage term of any bearing failure |
#104
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Babbitt gets hot enough to move around the shell and builds up and grabs the crank. Swapping an upper and lower shell where the lower doesn't have the oil hole can cause the mayhem. Except most bearing companies seem to use a pair of thrust bearings with holes in both shells now. Or too tight of clearances will cause the same result - maybe placing the cap on backwards ate up the thrust clearance?
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Mick Batson 1967 original owner Tyro Blue/black top 4-speed HO GTO with all the original parts stored safely away -- 1965 2+2 survivor AC auto -- 1965 Catalina Safari Wagon in progress. |
#105
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Quote:
Never had a main spin but when a rod bearing spins it will usually get hot enough to do major damage. Basically the bearing shell starts sliding under the other shell , if the 'clearance' is on the upper part, that makes the crank closer to the head/deck of block. (wedges the crank up when the bearing goes under the other bearing) I have heard they will squeal a little before they do it?
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John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
#106
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Cracked camgear usually means to me a loose front damper. Yet we would have heard about thaat by now.
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#107
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I agree. And the plugs look like they have no impact damage at all. They look like they were dropped on the ground and installed with the gaps already closed or near closed. If they were hit by a foreign object, they would be torn up.
Agree with the others that the thrust looks suspect and it could be spun bearings. The crank stopping with the cam still moving would account for the chip in the cam gear. To me, that is an awful lot of cylinder scuffing for a new engine, IMO. When I did the heads on my '67 GTO after 75,000 miles, I didn't have that much wear or scuffing. (Sealed Power Forged pistons installed during a 1988 rebuild). Good luck....it doesn't look catastrophic, so hang in there.
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Jeff |
#108
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I don't know, I guess anything is possible, but I've spun bearings bad enough, and got things hot enough, that the heat actually bent the crank, but the engine still wasn't locked up. The 2 pistons were contacting the bottom of the cylinder heads and it had .038 gaskets in it, plus the pistons were in the hole .020
When I brought the crank into Paul and he saw how black and blue it was from the heat he knew the crank would be bent. Sure enough, the heat on the pair of rods that it spun pulled the crank together in that area and I had to have the crank straightened, and then machined. Yet the engine still started and ran, and even still had some oil pressure. |
#109
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Yep, that's what I mentioned back early on, if the plugs were closed by a foreign object there should be some witness to that on the plug itself.
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#110
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It never seized, shut it off just in time. |
#111
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FWIW, In almost 50 years or repairing cars, and racing them, I once had a customer bring me a seized 360 AMC V8 in a 79 Wagoneer. Even though he had been warned repeatedly about revving a cold engine, he started it up and revved the crap out of it daily when cold. It finally caught up with him on a winter day, and he spun a rod bearing, and that bearing stalled the engine and locked it solid.
Of all the engines I've spun bearings on myself, and all the customer engines I've worked on, that was the only one I ever saw locked up. Most just destroy the rod/block, crank, and bearings, but continue to run, and don't lock up. The 360 was also a rod bearing, not an main, so if a rod can lock up an engine under just the right circumstances, a main also could under the right circumstances. The AMC engine only required a crank kit because the engine stopped immediately, the rod was still round. Like the main in the picture it only moved about 1/2 inch. New crank kit, and down the road it went until it rusted out. That is the only engine I've ever repaired with a spun bearing that didn't require at least one rod to be replaced. Unless it was a main that spun, which I have also seen, but that one ruined the block, it didn't stall and lock up, it kept running. Hopefully the damage is fairly benign, and the damage can be repaired cheaply. |
#112
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My imagination or the one piston pic in post 75 looks like a valve contacted the eyebrow?
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. 1970 GTO Judge Tribute Pro-Tour Project 535 IA2 http://forums.maxperformanceinc.com/...d.php?t=760624 1971 Trans Am 463, 315cfm E-head Sniper XFlow EFI, TKO600 extreme, 9", GW suspension, Baer brakes, pro tour car https://forums.maxperformanceinc.com...ght=procharger Theme Song: http://www.youtube.com/watch?v=7zKAS...ature=youtu.be |
#113
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He did say this was the first real run. So if the thrust main got hot and turned enough to close off the oil hole, that would cut off oil supply to the thrust main and related rods. Everything starts to seize up from lack of lube. Then he gets off the interstate just before it starts making noise, pushes in the clutch and the engine stops instantly. Best outcome in that situation, really.
What were bottom end clearances? Hopefully .0025-.0032" on mains and .002-.0025" on rods. Those aftermarket rods should have had .022-.030 side clearance. Crank endplay .005-.008" is where I'd want it all.
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I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 Last edited by chiphead; 09-13-2020 at 10:34 PM. |
#114
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I saw that too, wondering if the valve reliefs were correct for the heads?
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1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... |
#115
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Does that rotating assembly include an Eagle crank? Every 4.25" stroke Eagle crank I've seen in a 400 block required clearance grinding of the block near the rear main corner of the block at a minimum, and possibly elsewhere. The pics of the crank show very close block clearances to the crank throws, are you sure that block was clearanced correctly? Engaging/disengaging the clutch pushes the crank axially, insufficient crank/block clearance? Rule of thumb a paper clip should fit between the block and crank throws at all close fits to demonstrate minimum rotating clearance.
Just an FYI, the last 4.25" stroker I did used a Molnar crank, which did not require any block clearancing. First time I've seen that.
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1964 Catalina 2+2 4sp, 421 Tri-power 1965 GTO, Roadster Shop chassis, 461, Old Faithful cam, KRE heads 305 CFM, Holley EFI, DIS ignition. 1969 GTO 467, Edelbrock 325 CFM, Terminator EFI 1969 Firebird Convertible |
#116
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Even the stock 4" stroke 428 crank I put in a 400 block needed block clearancing in the back.
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#117
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Quote:
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1965 Pontiac GTO 455/469 w/ #48 Heads, '65 Tri-Power 9.25:1 CR Stump Puller Cam Muncie M22W 1st-2.56 2nd-1.75 3rd-1.37 4th-1.00 3.55 Rear Differential Front: 225/60R15 Height: 25.6" Rear: 275/60R15 Height: 28" |
#118
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bad pins in the pistons. maybe one broke, came loose, maybe more than one broke....or even the bottom of the piston that holds the pin broke
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1970 firebird, 468, e heads, |
#119
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Quote:
These are not domed pistons, they are dished. If the piston were to come into contact with cylinder head, the perimeter of the piston would smack quench area (flats) surrounding the chamber with plenty of clearance for the plug electrode. Also, if the pistons hit the three plugs and closed their gaps, where are the witness marks in the tops of the corresponding pistons. The phraseology of spun bearing is just that. The bearing turned (spun) in its journal and the tang on the back of the bearing causes the bearing clearance to close up and wedge the bearing tight against the crank. The bearing and crank heat up wedging eve more tightly and in conjunction with oil supply due to the bearing advancing and restriction or even fully covering the oil hole, the engine seizes. The the inertia of the camshaft turning (slack and free play in the rollers) while the crank stops abruptly sheered the corner of the keyway off. Also, there is a lot more metal in the oil pan than a chip from the corner of the keyway would create, plus it would still be pretty much intact as the the motor was stopped dead in its tracks when it would have dropped.
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Triple Black 1971 GTO |
#120
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He needs to check for rod small end to piston boss contact. On the motor I just built, I had to have the small end narrowed about .045" to have enough clearance when the crank and rod endplay stacks to one side. That may not lock it up, but it would make metal.
The ferrous metal may be bearing base metal or it may have come from the journals themselves. Could be from rod side clearance if it was much too tight. Can't really tell until you pull it all apart and inspect. When this thing goes back together, I would check the main saddle clearances and everything soup to nuts.
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I could explain all this to the girl at the parts store, but she'd probably call the asylum. White '67 LeMans 407/TH350/Ford 3.89... RIP Red '67 LeMans. 407/TH400/Ford 3.25 |
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