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What readings (warm) should I hope to find when doing a compression test on an MG 1600 and what %age variation between cylinders is acceptable?
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Compression Test for 1600
- Thread starter Michael Oritt
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jcatnite
Jedi Knight
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What cranking pressures you would find depends on the engine. Type of cam, timing, etc. I can't really say what they should be. The one thing that is pretty important is that they should all be withing 10% or so of each other. As the engine wears the cranking pressure will be a bit lower or it might take 4 or 5 cycles to get it up to full pressure. A new engine would build most of the pressure in the first cycle maybe 2/3's or so and then come up to maximum in the next couple of cycles.
JC
JC
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[ QUOTE ]
What cranking pressures you would find depends on the engine. Type of cam, timing, etc. JC
[/ QUOTE ]
I don't have any information on the cam but the compression ratio has been boosted to 11:1. Let's assume for the sake of the discussion that the engine has recently been redone and that bearings, etc. are in good shape--what is normal in an MG 1600 w/stock compression and what might raising the ratio do to compression readings?
What cranking pressures you would find depends on the engine. Type of cam, timing, etc. JC
[/ QUOTE ]
I don't have any information on the cam but the compression ratio has been boosted to 11:1. Let's assume for the sake of the discussion that the engine has recently been redone and that bearings, etc. are in good shape--what is normal in an MG 1600 w/stock compression and what might raising the ratio do to compression readings?
jcatnite
Jedi Knight
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I've read that you should expect between 17-20 times the compression ratio but you really can't rely on that. The intake valve has a great deal to do with it. The compression ratio that you are listing is 11:1 but that would be at running speed. Cranking rpm's are significantly lower and that would lead to lower cranking pressures. With that being said, I guess what I'm saying is it is extremely difficult to say what you should see for cranking pressure. I would guess that I would expect somewhere between 185 to 200ish? Like I said, it is more important that they all are within 10% of one another.
JC
JC