Well I wanted to see where my motor was at compression wise so I decided to test it out. The tester I used was not an outstanding quality one, but it was decent enough to get the job done. My buddy who let me borrow it says it reads low but my numbers seemed ok except for one cylinder. Looking at the engine bay it would go 148-129-148-148 so im not sure if the one lower cylinder is causing any issues so imput would be good. Obviously its ideal to have 4 similar numbers but I am not sure how low is too low. Any feedback is great, thank you.

BTW motor is a buschur 2.1 destroked

 

That 129 is to low. I'd do a leak down test now they should be within 10 psi of each other

 

I thought it was 15psi... either way, that cylinder is too low.

Are you positive that you followed the compression testing procedure properly?

 

Agreed. Leak it down and you'll find your compresion loss for sure.

 

not to sound like a jamoke but what is a leak down test? And I did do what I was told as far as checking the compression, and I checked a few times for each just to make sure.

 

Do the test again with a correct reading compression tester. Only mustang dyno'd are supposed to read low

 

It might help if you told us what you were told... I think either way you're screwed, because if you did it "wrong" then the cylinder pressures would be off, but they'd still have that drop.

I understand that accuracy is king in this case, but shouldn't it not matter how "accurate" the gauge is so long as it reads appropriately? I mean... if the gauge said 249 for 3, and 220 for 1, versus 149 for 3 and 120 for 1, it would still mean 1 is low no?

 

I took out 1 spark plug at a time and threaded the comp tester in each of the 4, and let the motor crank 5 times. Did I miss anything? Also I am in agreement with propilot04, because nomatter what numbers it puts out, if 3 are the same and 1 is lower, it still seems odd

 

Leakdown buddy! Hopefully you dont need a rebuild allready pullmaster.

 

Aren't you supposed to take ALL the spark plugs out?

 

no def. not

 

Yes take them all out! :P

 

Yes def you are !!

 

what? I was told to take 1 plug out at a time? wtf

 

You take them all out so the motor is able to rotate faster