Did a compression test today and here are the results:

1º cilinder 180
2º cilinder 217
3º cilinder 232
4º cilinder 212

He´ve found that an intake valve is losing 35 % compression pressure, in the 1º cilinder.
Also the valve adjustment was diferente from the others, it was at 0.004 inches, in the 1º cilinder.
All other valves clearences were bettwen 0.006 - 0.008 inches.

So, do you thinks that 0.004 in wich is bellow the stock tolerances might damaged the valve or the valve seat ?
Do you think that it might be ok in the next miles or i´ll have to open the head and check for all valves ?

As for the dyno results i got 172.3 at wheels.

Please help me out on this.
Thanks in advance.

Pinota


[Modified by pinota, 3:09 PM 8/21/2002]

 

With a milled head and decked block, plus 11.5 pistons, you should be over 250 for compression. The numbers should be within 10-15 psi of each other.

Did you do this with the engine hot, and throttle wide open?

Warren

 

This was with the engine hot and WOT, just with the starter. ( 6x )


[Modified by pinota, 3:11 PM 8/21/2002]

 

shouldnt your compression be close to 12:1 with the pistons and milled head. Your psi numbers should be around or max at 280. With CTR piston I easily hit 300 psi in all cylinders. It could be more but my needle stops at 300 psi due to the needle stopper at 300 psi.

 

what should 100% stock compression be?

 

isnt around 220 or maybe 240

 

Well, if you don't open the throttle plate, how do you think more air will make it through there?

Go warm it up again and floor it while you are cranking during the comp test.

Warren

 

you have all that doen to your ride and your only putting down 17X.XX to the wheels???

 

I´m having a 35% leak on a intake valve. I´m losing a few gain in high end.
Also running a twin loop exaust wich is kiling my high end too.
Owr dyno machines are very diferente from US, i did the dyno in 5º gear.

More thoughts on the compression results.

Pinota

 

What are those clearances for that you were referring to?

How many miles are on your motor? I know it hasn't been that long since you rebuilt it.

-kenji

 

Those are the stock valve clearance adjustment:

Intake: 0.006"-0.007"
Exhaust: 0.007"-0.008"

In the 1º cilinder, i had in the intake valves clearence at 0.004". ( during 2000 miles )
In this cilinder i had 180 psi and a 35% leak on the test, we could hear the the air on the TB in WOT during the pressure leak test ( sorry about the translation ).

Do you think after the valve clearence adjustment to Intake: 0.006"-0.007", wich they already done will make the leak disapear and raise the compression on the cilinder ? ( at least closer to the other cilinder compression )

I ran my engine after rebuilt for 2000 miles.

 

what are your leakdown numbers? Listen for where they are coming from. If you can hear it in your manifold then its your valves. if not, then its your piston rings or your head gasket.

 

I can hear them on the manifold.
We´ve had the intake valves closed in the 1º cilinder and we could hear the air on the manifold and TB.

The leakdown on the 1º cilinder is 35% ( per cent )

Pinota

 

Set your #1 valve lash within factory spec and test again.

Why are you running such a tight valve lash on the #1 cylinder? Are all your valves adjusted this tight?

-kenji

 

It was a mistake of the mechanic.
All other valves lash were ok.

They´ve adjusted the intake valves on the #1 cilinder but it only raised a few psi on the compression pressure.
I drive about 200 miles now and i´ll test it again.

Pinota

 

nothing is going to change, you just recently rebuilt that motor....there should be no leaks. Id have the mechanic who did the work recheck everything and if it was his error.....he should get his **** in gear and fix it. After i had my motor rebuilt I made sure to witness a compression test and leakdown test.