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Discussion Starter · #1 ·
I have gas ported big chief J & E pistons. Can you get an accurate reading on a cylinder when you are checking them doing a leak down? I have a problem with all my cylinders leaking at 40 to 50% hot or cold. I have only three runs on my engine.
 

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Procharger Power
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You should get a good reading as you are pressurizing the cylinder which in turn will force the ring against the cylinder wall with more force. How much end gap are you running?
 

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Discussion Starter · #7 ·
This is a nitrous motor. I ran the car on the bumper for about 40 feet. I don't think I hurt the motor for that short of time. The top ring end gap is 45 thousand.
 

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Still seems like way too much leakage. With that amount of leakage, you should be able to hear where the leak is coming from (intake manifold, exhaust pipe, crankcase vent, etc).
 

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Still seems like way too much leakage. With that amount of leakage, you should be able to hear where the leak is coming from (intake manifold, exhaust pipe, crankcase vent, etc).
Thats what I am thinking, if its that bad you should hear it going somewhere...
 

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Discussion Starter · #11 ·
When i checked all the holes on TDC . All the leaks came from the crankcase. I will have to check the bore and piston cleance. I have a Donovan block . What type of piston clearance for a nitrous motor
 

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Procharger Power
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When i checked all the holes on TDC . All the leaks came from the crankcase. I will have to check the bore and piston cleance. I have a Donovan block . What type of piston clearance for a nitrous motor
Depends on the bore size and the piston manufacterer.
 

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I have gas ported big chief J & E pistons. Can you get an accurate reading on a cylinder when you are checking them doing a leak down? I have a problem with all my cylinders leaking at 40 to 50% hot or cold. I have only three runs on my engine.
Ive personally watched a SBC leakdown like 3% BEFORE it was taken off the engine stand!
 

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At 3 runs is it possible the rings are not 100% seated yet?
Not a chance. After one pull, it will pretty well leak what it is going to leak. Three runs with nitrous, well thats much more cylinder pressure, so rings will seat even quicker. BG
 
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