Is 200 lbs of cylinder pressure high

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tistan2

New Member

Feb 29, 2004

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Jun 1, 2004

#1

• Jun 1, 2004

• #1

I bent a couple of push rods so I did a compression test to see if the valves might be bent. The cylinder that had the bent push rods read 195 lbs and the highest cylinder was 205. I know stock should be between 130-160. My heads are afr 165 with a 58cc chamber. Would this be why my cylinder pressure is so high or is there some other reason. The shortblock is the original with 175,000 miles on it.

 

Mike86Stang

Advanced Member

Apr 11, 2000

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Red Lion, PA

Jun 1, 2004

#2

• Jun 1, 2004

• #2

i"d be willing to bet the exhuast valve pushrod is bent keeping pressure in the cylinder

 

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tistan2

New Member

Feb 29, 2004

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Jun 1, 2004

#3

• Jun 1, 2004

• #3

all the 8 cylinders were reading that high

 

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87'GTstang

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Feb 16, 2004

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Jun 1, 2004

#4

• Jun 1, 2004

• #4

If it was just one pushrod bent, it would be just that cylinder. How do you know you bent a pushrod? Also you have heads with 58cc combustion chambers - this raised compression over stock anyway. 200 is not too high but it is possible.

 

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tistan2

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Feb 29, 2004

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Jun 1, 2004

#5

• Jun 1, 2004

• #5

I pulled the intake off and the pushrods were bent.

 

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Silentst2000

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Sep 28, 2003

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Jun 1, 2004

#6

• Jun 1, 2004

• #6

Are your springs a lot stronger than the old ones?

 

408stroker5.0

The world would be a better place if all males jus

Mar 10, 2004

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Bonnyville, Alberta, CANADA

Jun 1, 2004

#7

• Jun 1, 2004

• #7

Your spring's may be too stiff which could cause the pushrod's to bend. Are you using a stock cam??? If so the spring's that come with the AFR 165's I believe are too much for a stock cam, thus causing serious coil bind. As for the compression... 200 is high but I woudn't complain. Although MSTANG may be right as well.

 

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SlowGT

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Jun 17, 1999

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Columbia Co, PA

Jun 2, 2004

#8

• Jun 2, 2004

• #8

How much do you suppose a pushrod would need to be bent in order not to move the valve at all?? Consider stock lift when figuring it out. It seems to me that if it were bent that much, you would definitely here some saddening sounds from the motor. I'd guess you'd need close to .500" deflection to shorten it .444". I haven't been intimate with my geometry lately, so that's just a guess.

58cc heads on a stock block should yield around 10.5:1. 175,000 miles of build up on the pistons will raise that figure a little bit. My pressures were 180-190. You could gain/lose 10-20 pounds depending on the condition of the rings.