Compression testing the cylinders…..super low!
 

If you followed my posts at all, it’s a 454 bored and stroked and yields 10:1 compression approximately. The problem I’m having is I decided to test the cylinder compression before putting this in the boat. The compression on every single cylinder was between 0 and 15psi. I popped off the head covers, re-did the rockers and now the cylinders are consistent 30 psi one through eight, is this low because the rings haven’t been seated as it’s a brand new build? I was expecting the compression per cylinder to be upwards of around 150 psi.

forgot to mention, the crank is getting two full rotations as I’m testing.

Are you sure you are running the valves and setting the lash correctly ?

This is basically how I set lash

Ill ask a dumb question, are you testing compression by using the starter to crank the engine

Is this a new motor?
Are you making sure that your throttle is WFO so it's pulling air in unrestricted?
Another thing you can try is to spray a little WD40 into the cylinder to see if it goes up.

even if it is a new build, compression should be much higher ! something is not tight! did you do a leak down test to find where is the leak ?

it’s a new build. I’m cranking it by hand. I cleared all the noise out of the shop and did it again. I plugged the spark plug hole with my pinky finger. I feel the pressure start and then it backs off, it’s leaking somewhere. I looked at the valves. They aren’t bent.

didn’t do a leak down test. I’ll push compressed air through the spark plug hole and listen for noise…

oh and the carb is off, engine gets all the air it wants.

You cant do a compression test like you are doing it, you need piston speed and about 3 or 4 full cranks around with the starter and all the plugs out except the hole you're testing.

EDIT: I hope there's oil in the engine, you need to crank it with the starter to pump the lifters up

/facepalm

yes there is oil in it. Gonna rig up the starter to a jumper pack with a makeshift circuit tomorrow and seee what happens.

still probably a good thing I did it since initially I was having zero compression and now I’ve got 30 in all cylinders. Would have to pull the motor from the boat in order to get the valve covers off and redo all the rockers.

Question, did you prime the engine through the distributor hole ? I wanted to wish your wife the very best in a speedy recovery, cant imagine what you both are going through.