Hello, I have a problem with my engine after rebuilding it in a nearby garage .

I rebuilt the engine several weeks ago and noticed a decrease in engine power.
I decided to check the pressure of the cylinders. After the examination, I found that the pressure of all the cylinders was equal, but the pressure was low at 120 psi for all cylinders (knowing that the basic pressure is 170 psi).
Then I checked the pressure leakage and there was no pressure leakage, what is the problem?
Knowing that the cylinder head is new


do i have to do resurfacing for cylinder head to get more compression ?

 

Seems plausible..

What was your block bored to, what was your deck heighy machine to?

 

And do you know thar your gauge is accurate?

 

Unfortunately, I don't know, but the workshop owner says that when rebuilding the engine again you need a cyilnder sleeve,I don't know if that helps.

I will borrow my friend pressure gauge to see if mine was inaccurate.

Even if the gauge was inaccurate and the pressure became within the appropriate range, what is the reason for the engine losing its power?

 

Is it throwing qny codes?

 

22r without ecu

I checked the cylinder pressure again with another gauge, and I got the same results.
Could the workshop have put double head gaskets which could be the cause of the low pressure?

 

What are the full test results.
Cold vs hot vs wet.
What is your cranking rpm.
Are you providing extra current via jumper cables or a starter box.
Are you holding the throttle wide open.
Are you cranking untill the needle stops climbing or just counting a few revolutions.

All of these make a difference in the accuracy of your test.

No it's very unlikely your builder put a thicker gasket in it, and almost certainly didn't put in two of them.

Your block has had its cylinders bored out (this reduces your compression ratio). It may or may not have been "decked" (this is were they machine some of the deck height off to bring the surface back to level), this will raise the compression ratio but has a side effect of retarding the valve timing. Retarding the valve timing will also effect your air flow such that it shows a lower number on a compression test because the valves open and close at less than ideal times.

..
Re do your compression test. Make sure you have the throttle wide open. Hook up a secondary power source. You want close to 300rpm from memory (more than 200 but less than 500 typically). You're going to crank untill the guage stops making any significant progress while keeping track of how many pulses (revolutions).

On a pad of paper chart these for each cylinder.
Cold pressure Rev count.
Wet pressure rev count.
Warm pressure Rev count.

Now get a chopstick or straw, your tools and a buddy.. Pull the valve cover and sparkplugs. Hand turn the crankshaft and locate TDC (cylinder #1 valves start to close, timing mark approaching Zero) one of you is going to turn the crankshaft the other is going to be watching the stick hanging out in the #1 sparkplug hole. Ideally you'll find the stick stops moving right at the Zero timing mark and the dowel on the cam is straight up at the 12 o'clock position.

With some luck you'll find only one of two issues, but I expect you're going to find both the cam timing is off (this ones not horrible to fix, LCE sells and adjustable cam gear.) And that your wet compression test was much much higher indicating compression ring issues.


EDIT:
I just reread, you did a cylinder leak down already. You might still get five or ten percent higher with a wet test. But it's likely the valve timing combined with the compression ratio. There isn't a lot of room to play with in the deck height to gain back ratio.

 

Check your oil for fuel? Heavy fuel smell could mean your flooding the cylinders washing the oil off the cylinder walls. Try putting a Tbsp of oil in one of the cylinders before you run the compression test again.

 

i have already did wet compression testing and i got around 7 psi more , but didn't do cold testing , didn’t get a secondary power source ( i have got around 200 rpms) nor opening the throttle.
i will re do compression test with all the info you gave me. after getting the results i will do the cam timing test then will post everything here
thanks

 

hi guys update on the compression problem i ran the test again taking in consideration opening throttle and another power source to power the starter.
the results are :
1#161
2#163
3#165
4#161
which i think is great
I guess the problem of low compression was lack of electric power and air from closing throttle.
i think the problem i have is from the new carburettor maybe !?
i have bought “weber” carburettor, i think it’s fake and i have got bamboozled.
when i give it gas, engine dies then get back and accelerate normal.