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Discussion Starter · #1 ·
Doing LS swap and finally got the motor in and married up to the th400. When trying to connect flex plate to the converter, I noticed I could only rotate the engine so far, about 270 degrees, give or take.
Pulled the pan and can’t see anything there, I took out the bolts connecting converter to felxplate and that didn’t do anything.
Prior to installation I pulled the front timing chain cover and water pump to put in a new oil pump. I can’t for the life of me remember if I turned the motor completely over by hand after doing that but it definitely did before and I thought I rotated it over completely after the oil pump It seems odd that it turns over very smooth until it hits a certain point each time.
2 thoughts, something going on under timing cover after instal of the oil pump. Or second option is something got dropped into an exhaust port or intake port or something and won’t let the motor turn past that point.
really would rather not tear it all apart just searching.
Maybe something anbout being connected to trans now even though Converter and flexplate aren't attached. Converter spins freely.
Any ideas before I dig in?
 

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Discussion Starter · #4 ·
The motor is a stock 5.3 that came out of a running truck so I felt pretty confident that the valvetrain was installed correctly. I was trying to think back to changing the oil pump if that could have changed anything but I can’t think of how that would happen.
I tried to look in spark plug holes and didn’t see anything.
I may need to start pulling it apart as I am scratching my head what could be the problem
 

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how do you bump up against compression
I think he means while turning it over by hand, not with the starter. You know when you reach that point of a completely sealed cylinder and the crank won't go further by hand unless you rail on it with a monster cheater or breaker bar... Correct me if I'm wrong, Ken @unstable
 

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@PldBryan , Let me ask, do you have all plugs out when attempting to spin the engine over past 270°? IF so, not a compression issue, would have to be a mechanical issue by interference either in rotating assembly or by obstruction in a cylinder.
 

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I think he means while turning it over by hand, not with the starter. You know when you reach that point of a completely sealed cylinder and the crank won't go further by hand unless you rail on it with a monster cheater or breaker bar... Correct me if I'm wrong, Ken @unstable
I was making fun of the comment not looking for an answer

there are 8 cylinders. 8 compression strokes for every 2 turns of crank
how is compression stopping it from turning at a specific point but has no problem elsewhere
 

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I was making fun of the comment not looking for an answer

there are 8 cylinders. 8 compression strokes for every 2 turns of crank
how is compression stopping it from turning at a specific point but has no problem elsewhere
I get it. Sorry, kinda early to be thinking clearly on my coast :p took the day off and still woke up at 0430.. I missed the rhetorical content of that :) UGH. What do you think could be the issue given the information we have to work with? I know that's asking a lot considering how little we know...
 

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Yep, plugs are out. I know there isn’t a ton of info, kind of a shot in the dark. I plan to start tearing into it today hopefully.
Have you turned the engine over both CW and CCW? same 270=/-°? If you start tearing into it, I would start with what you worked on last and work your way backwards. Maybe take off the rocker covers to watch for interference...
 

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dig in, we can speculate all day long, but even if someone nails it still need to dig in to confirm and fix

pull tranny right off, see if it turns
pull starter
look around flex plate
then go to the area that was already altered...oil pump, which requires timing chain to come out
could be issue with pump or something foreign in pump or timing chain/gears

you should have been turning engine while tightening down oil pump....what method did you use to align oil pump....there is alot of nonsense on youtube about that
 

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Discussion Starter · #19 ·
I used an alignment tool for the oil pump so felt like it should be ok. I will triple check how I set the timing marks but remember clocking them in per the instructions.
 

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shouldn't be timing either
say timing was so far off that a piston hit a valve, and that stopped you from being able to turn any more
It would be the same for every piston so no matter where you started you would not be able to go more than 90 deg as one of your 8 pistons would have that interference

you haven't been too clear about exactly how much you can/cannot rotate
can you rotate back and forth with it always stopping at the same place
how much can you rotate
 
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