what should compression be on a hot engine?

[pulsarmad20]

as above really !!!
any advice thanks

 

[red reading]

Depends on alot of thing's from head gasket to cams to piston's blah blah

 

[pulsarmad20]

car is bog standard from wat i know!! lol apart from air filter exhaust and dumpvalve

 

[red reading]

150psi, but it will vary due to gauge's being in-accurate,the main thing to look for is no more than 10% differance between cylinder's, a leak down test is more accurate too btw.

 

[pulsarmoley]

So as i found on my engine cylinders 1,2+4 were @ 157psi but cylinder 3 only 91psi :doh:

 

[PobodY]

I think you've just found your problem with the rough idle and the misfire...

 

[pulsarmad20]

what is the problem then ? as im going to do mine on monday why would the compression be down?

 

[skiddusmarkus]

Head gasket, rings, hole in piston, valve.