COMPRESSION TEST RESULTS PLEASE HELP!!

[stang9210]

Hey I just put new trick flow twisted wedge heads on my 1992 mustang gt HO 5.0, left the stock cam in there, put on the trick flow 1.6 rockers and pushrods.

I did a compression test in the cylinders once I adjusted the rockers, I seemed to have good compression in all cylinders except #5. I did a dry test and had 100psi in number 5 and then did a wet test and got 120psi. The motor also hasn't been run in a year so this was a cold test. These were my results

1. 160
2. 170
3.170
4.170
5.120
6.153
7.170
8.150

Can anyone tell me why this cylinder would be low, could it be a burnt or bent valve even though the pressure went up on a wet test or could it be a problem with the short block. The heads are the only new part on the engine, and it's the stock block with 100k on it. It hasn't run since it was tore down though, I'm using oringed felpro gaskets also. The motor seemed to be running good before the tear down, but i was getting bad fuel mileage like 12mpg city with a bone stock engine. Any imput would be really appreciated

 

[Fast63]

you didn't do a compression test before the swap?

Your rings are bad, not the heads. If any valves were bad on a new cylinder head, you would have ZERO compression in a cylinder

 

[93 LX]

if oil makes it go up then its bad rings

 

[347HO]

you didn't do a compression test before the swap?

There are a lot of people who can learn from this example and this post.

 

[thumper460]

From 100 to 120... I would think you kissed a valve on the heads while you were making the adjust!! IF you can get the engine warm, then try the dry/wet test again... the oil could have need OFF the rings and needs to get warn to help seal the WEAK rings.. after the warm wet/dry.. IF the cylinder is still as low... time to get the heads off!!

Just me..........................

Thumper