Engine Trouble Recently Rebuilt engine won't start

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yeah, that low seems like seals or crack in cases
 
okay, How can I confirm that it is the crank seals? would any fuel/oil be coming out of them? also how do you go about replacing those seals? they seem like they are going to be hard to get out and get new ones in
 
I would love for someone to explain to me how a crank seal will drop the compression by 60 PSI. I got the dry ring theory but a lose of 60 lbs seems rather extreme for a crank seal.
 
air/fuel intake goes to bottom end - no seal lessens what gets in there and also prevents it from being pushed up the transfers into combustion chamber

motor without a seal usually measures 25 to 30
 
air/fuel intake goes to bottom end - no seal lessens what gets in there and also prevents it from being pushed up the transfers into combustion chamber

motor without a seal usually measures 25 to 30
crassius I love ya, and like what you bring to the forum. I've heard this idea for too long, and it's just wrong. the effects of a crank seal are so minute that they have no place in this conversation. The atmospheric pressure is in most cases 3+ times greater than that produced by the by the lowering of the piston. They are a constant. To suggest anything else is simply in need of evidence. Here's mine. New nutin fancy engine with minor port work. With seal, without seal.
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newer motors may have a main bearing with builtin seal - when new, that seal will help to hold some pressure - as it ages, it will hold less

for 10 years or so, whenever I see 25-30 pounds, I also see a seal popped right out - feel free to believe whatever you like
 
So you replace the seal and it increases it's compression by 60+ PSI? No way. I'm not believing what ever I want I'm believing what I have proven.
This bearing seal is pried open. I can feel the case pressure coming out on my finger. Their is no change in compression. The crank seals have no significant effect on cylinder compression. I'm not saying you haven't noticed popped seals in engine with no compression, while they could have lead to the cause of of low compression they are not the direct cause of it and replacing them alone will not restore proper compression.
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think about how it all works - each swing of crank adds to pressure in chamber from last swing until an equilibrium is struck

with no bottom seal, as piston comes down transfers are opened and all pressure achieved flows out the bottom leaving you always on first swing with no pressure to add to

one could poke a big hole thru seal on the main to see
 
Yes think about how it works. As the piston comes down the case pressure is 3 to 7 lbs. and has no real effect on the cylinder compression because it has become equal if not somewhat negative when the transfers open because the exhaust is also open and quite often creating a scavenging effect. The experiment speaks for itself. Look at the pictures. the seal on the main bearing is peeled back. You can see the bearings. The case is not holding pressure, and the cylinder compression does not drop. I was just thinking I know how sometimes you have troubles with your puter so maybe you haven't been seeing the pics. I have been posting along with this discussion. Anyways I have run the test with and without case pressure and the compression stays the same.
 
the other half of builtin bearing seal is INSIDE the case
 
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