Low Compression... why??

[Nismoka24e89]

I am going through with 3rd engine and this 3rd engine is hell than other engine i have worked on...

I am dropping in 3rd engine because the 2nd engine had a bent valve while i was racing hard against DOHC and valve got stuck and piston hit the valve, I replaced the valve and resurfaced the head and cleaned and port polished it then installed back on the motor and put it in.. tried start... no luck.. of course i lined up the timing and the mark is at 3oclock and close 5oclock... and i am getting nbr 1 50lbs of compression (thats where valve bent on nbr 1) and nbr 2 and 3 and 4 getting 25 lbs of compression... what is this??? this is so new to me!!! last time before i drop engine in.. i was getting 80 lbs all way over by turning with hands and now i got it in with starter and wanted to see if i get more but i am wrong.. i am getting low compression... or is the gauge bad??? lol... I am about to pull it out and trash it and drop in another ka24e.... Can anyone help me out?

[Checkered-Member]

engine needs to be at operating temperature to give an accurate reading,is the throttle blocked at wide open?is the battery fully charged?

[Nismoka24e89]

No i didnt press gas all way down but the compression should show about 20 to 40 psi less than the normal tempture... will find out soon.. thanks for letting me know..

[InsanityInc]

if your cam phasing is jacked up your compression will be, too.

[DjPantsSpecR]

absolutely, also you only bent one valve? lucky bastard. anywho, you failed to mention if you had the valve you purchased cut for the head. that valve may never seal quite right.

Definately recheck your cam timing before you try to figre it up too many times unless you worship bent valves

[BigLeeRoy EngineBuilda]

did you lap your valves. my engine did the same. well it did it to the previous owner. while lappin the valves i noticed that the valves were smooth all over but in one spot. the valve was bent just enough to where you couldnt physically see it. and the whole warm the car up thing i have never done that and my readings were good. but hey i am gonna try and warm it up and do the test and see how that goes. (damn i learn something everyday).

[InsanityInc]

cold-warm isn't going to change your compression by 130psi. Also, the listed psi reading is only accurate at the RPM that the starter turns the engine at. My guess is cam phasing. Mine were off half a link and my compression raised 40psi across the board when I fixed it.

[brisknfade]

Quick question. Would running a compression test having the throttle completley close affect the results by much?

[DjPantsSpecR]

yes sir