My motor got 700miles on it and i do a compression test and i got 270/240/210/240...the motor is brand new from a refresh (GSR with 82mm ctr pistons) oversized valve too.

the setup is not tune top notch, the plug is showhing thats is rich. The thing i want to understand is why i have one with 270 and the #3 210...last week i got 245 on each cylinder...so now i'm lost lol

thx for the help!

 

I hope you bored the hole to match the slug, because pistons are not exactly 82mm in diameter....

I also hope that you gapped the rings correctly...

Could also be caused by a crappy valve job.

I think you may have a inconsistency in the valve job or the bore.


Modified by slowcivic2k at 10:58 PM 7/17/2007

 

the #'s may even out with more miles. also may need to overlap the valves to get them to seat right

 

the bore job is perfect and the valve job too...i just find that weird because last week i have 245 in each cylinder and now i got difference.

 

What was the piston to bore clearance of those pistons... I highly doubt it was perfect, and with a variation like that, I have no reason to believe that it is.

 

yeah but for 650miles i've got 245 on each cylinder...if i had bad clearance of the bore, this problem was been there from the begining right?

 

Not necessarly, if the bore was clearanced poorly, the pistons will simply beat against it and make the gap larger, and will not properly allow the rings to do their job.

How did the machinist perform the valve job? did he lap the valves to the seats? Or did he just throw them in here?

Are you showing any signs of leaks on the spark plugs?

 

the oversize valve job is perfect, no leaking there, and my plug and black...he run rich, well in the air/fuel gauge, tomorrow the car will be tuned.

 

200WHP@8200

 

wow ! now tell us your complete seutp

 

200WHP@8200 on a mustang dyno
MODS
gsr block with 82mm CTR pistons
CTR head NO PORTING
CTR camshafts
ferrea oversize +1mm valve
supertech valvespring/retainer
AEM camgear
AEBS intake port match
dh-racing 71MM TB
450cc dsm injector
aem fuel rail
aem c.a.i.
custom 2 3/4 exhaust
F1 tri-y headers
fidanza flywheel
hondata S200




Modified by allmotorslut at 9:47 AM 7/27/2007

 

Man the motor have a problem...the compression is now 250/240/170/210...i will do a leak down test asap