Compression PSI question

[Dutch]

I have read that the standard Compression PSI for the KA is a minimum 149 and standard 179. I had a tired Ka24DE that when I did a comp check came to 120 psi reading. Had a crate engine installed, new head, block complete rebuild/ I have 100 miles on it and checked it to now only read about 128 psi. The only things i didnt do as spek'd while checking is to releive fuel pressure and remove all 4 spark plugs. only #1 was removed. Any idea why a new motor isnt hitting at least the minimum 149 if not higher?

[navysnail]

remove all 4 and release fuel pressure, it will make a difference.

[candela]

and open the throttle...

PS- my KA reads 225-235 like whoa :p

[Dutch]

OK... I releived the fuel pressure and pulled all 4 plugs and opened the throttle and I rechecked and came up with 150 on 1 and 2 and 140 on 3 and 4, still not up to the minimum, maybe the compression rings / valves need to seat? I did warm the engine a bit before the test too. Any ideas? Candela... and that's PSI?? THats great..

[candela]

It will most likely go up after a couple hundred more miles.....

Yes its PSI but its casue of carbon buildup :p

[MikeMurphy]

Did you test it after it had warmed up? Ah, you did.

180-185-190-185 <--mineThe KA FSM recommends that each cylinder is within 14psi of each other.

Get in contact with whoever did the work or sent you the parts immediatly. Tell them your situation and get their suggestions in writing. Also dont forget to get them to date it. If their suggestions fail, get them to fix it through warrantee or get a refund later on.

You should have 172psi or so right out of the box with zero carbon buildup.

[Dutch]

Is there any other step i need to take to remove the fuel pressure for an accuarate test? I pulled the fuse from the fuel pump curcuit then disconnected the inlet fuel line. I looked for a pressure relief check valve like my Jeep has but didnt find one.

[NISTECH]

no pulling the fuse will relieve the pressure. I dont believe an engine out of the box wil give real accurate readings till after 500 miles as the rings need to seat properly. when you are doing the compression test do as mentioned above[no fuel ,plugs out,full throttle] but also count the lopes of the engine go approx 8 to 10 on all cylinders. this will give you a pretty accurate reading. A little hint to on doing compression checks. watch the gauge on the first hit. with a good battery in the car you should see between 70 to 100 psi on that very first hit. That hit is a strong indication on how well the cyl is sealed. if it is below 50 you got something wrong in there.

[Dutch]

OK, I'll try it again when I get home and see, then again i n a few more miles and report back, Thanks for all youre help!!

[leper421]

Put some oil in each cylinder, if the compression goes up, your rings arent sealing properly.

[Dutch]

I now have about 630 miles and have these results... 1 -165 2 -160 3 -155 4 -153

The engine importer said they now build them with lower compression since the quality of gasoline around the country isnt as good as it was when it was built in '93. The card pulls great but I cant help thinking how great it would pull with 190 psi on all 4.