I just got done installing a new motor in my 89. I took it for a drive and it runs alright. I am a bit worried however.. It doesnt have the power i expected. The motor has a ported head, 9.7:1 comp. a cam ect. and doesnt seem too impressive. I checked the compression and it reads: #1- 130 #2- 150 #3-140 #4- 120.
I am a little concerned with these numbers beings it should be around 170psi or so.
Any thoughts??

 

Something does not seem right.

They should be much closer matched and 160+ depending on head stuffs.

How new, proper brake in ???

I hope some one smart comes along w/ some real answers.


Repo

 

Yea you are still seating your rings. Don't worry too much about compression early on. And the power won't come until you really break your engine in (I've read it may take 5k miles to feel the power). Heck you might check the torque on your head bolts just for good measure. Most people recommend checking them at 500 miles anyways.

 

As said earlier the rings are still seating, drive slowly the first 5000 or so miles. Don't keep the rpm in the sames place for to long at a time.

 

x2 gnarly is right, you cannot baby a rebuilt motor. How did you break in thew motor before first driving it. You should have let it idle at about 2500-3000 RPM varying throttle but not letting it go below 1500 rpm for about 20 minutes to a half hour to break in the cam and somewhat seat the rings. Then you should have changed the oil and filter, went back in re-torqued the head bolts and then check and/or set you valve lash while the motor was still warm, then proceed to do what gnarly said.

Also keep in mind, any machine work done to the head and/or block deck surface will change cam and thus ignition timing. Discussion somewhere on here that I was involved in regarding 0 decking the block and the relationship between how many thousands of machine work to either head/block and the degrees advance and retard it will give to the cam and ignition timing.

If there was any machine work to the motor you will at the very least have to adjust ignition timing to compensate somewhat and not use factory ignition timing numbers. An adjustable cam gear would also be a good idea if the head/block was decked 20 thousandths (???) or more and a head shim was now used to compensate for the machining. (still in the works on getting mine from LCE as I had the block shaved that amount on mine and a new head was installed without using a shim.)

 

Thanks for all the response! Pretty much all i have done is break in the cam and drive it for maybe 15 minutes. I pulled it back in the shop because something just did not seem right. I have checked over everything, adjusted tps, checked valve lash ect.... Honestly,this hopped up motor does not seem any more powerful than my old stock worn out motor.

I guess i am just a little worried about the compression.. The low numbers could be my lack in power??