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Join Date: Feb 2017
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perplexed - normal? engine rotation

help wanted!

Good afternoon- had a strange thing happen and wondered if anyone out there has experienced/might now what is happening.

At the tail end of a rebuild - and nearing putting the engine back. Everything was going fine - all tests done etc - everything turning great etc.

I ordered a new flywheel and clutch assembly so dismounted the old flywheel (was torqued, but not all the way spec).

all I have done is mount the new flywheel, put the plugs in, put the valve covers on, and the engine mount bracket.

I tested turning the engine again and it is going, no binding etc, but it almost feels like there is air pressure building on the opening of the intake valves. Turning the engine is not as smooth like it was just prior to those items above done. Also, I hear some air coming out of the crankcase breather, sounds like a small leak or pressure release sound- is this all normal?

Is it possible that removing the flywheel and putting the new one on did something to the alignment inside the case??? Again, nothing is binding - just 25-30% harder to turn on the intakes and it feels like some pressure pushing against turning.

thanks everyone.
Old 04-15-2018, 11:01 AM
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pull the plugs and try rotating again and see if that makes a difference
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83 911SC Cabriolet
Old 04-15-2018, 11:10 AM
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Gary, don't mind pulling the plugs - but what/why would they cause a specific problem as discussed?
As I look down the intake valve I can see the plug end and no binding etc. Just wondering. Thanks
Old 04-15-2018, 11:17 AM
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Thanks Gary - just read in the tech articles on Pelican that when doing a valve job that you should leave the plugs in ("taking them out will make the engine turn easier but...") - I guess it is just the air pressure - i iwill take out just to make sure -
Old 04-15-2018, 11:32 AM
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Dude, you’re building compression, that’s a good thing. With the plugs out, there is no compression as it escapes through the spark plug holes. You’re fine.
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Old 04-15-2018, 11:55 AM
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Yes, with plugs in you no longer have any escape path for the air you are compressing by moving the piston up while the valves are closed.
This is why I think every kid should have a dirt bike growing up. You'd know what the pressure was a result of because you'd have scars on your shins from the lesson.

Good for you for tackling such a major endeavor! You'll learn way more than you thought you would when its all over. Especially if you have to redo some parts a time or two.
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Old 04-16-2018, 11:49 AM
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You put the plugs in.
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Old 04-16-2018, 12:20 PM
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Quote:
Originally Posted by pampadori View Post
Yes, with plugs in you no longer have any escape path for the air you are compressing by moving the piston up while the valves are closed.
This is why I think every kid should have a dirt bike growing up. You'd know what the pressure was a result of because you'd have scars on your shins from the lesson.

Good for you for tackling such a major endeavor! You'll learn way more than you thought you would when its all over. Especially if you have to redo some parts a time or two.
Thanks - it has been a huge learning curve - doing the p/v check, deck height, timing - all fun and then to see if actually turn without binding....now getting ready to reinsert the engine - just did all the oil lines in steel braid - posted another question on that - the oil system is definitely harder to follow than a small block chevy!
Old 04-23-2018, 04:58 PM
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