So... before I go spending too much more time and money on the truck I wanted to get an idea of engine health. Didn't want to spend the $300 on compression adapter and guage ..... so manometer.

My results were 2" at 2200 and 3" at 2800 ....

 

Problem is this I s about NEW engine spec .... so I think some things astray. Most obvious would be too much venting somewhere .... but my front gear vent is blocked off .... 

And I run a dual billet side tappet.... 

1 was blocked.

Other was blocked with 15/64 hole.

Measured from dipstick with clear tubing .... pics to come. Any ideas of where I'm venting or ....?? 

 

 

In your case I would do each cylinder separate and rotate the engine. Look at the intake rocker. Once the intake is closed rotate it a little ways further. This way each cylinder is on the compression stroke as you do it. More time consuming but there's no way you're going to mess it up.

Keep turning it over, it's hard to tell in the video, but it appears like your turning the engine over backwards.  If that is the case you have to have the intake closing right as the exhaust is opening.  They should literally both be open at the same time.

You can tell which way your spinning the engine by looking at the fan, it should be spinning in a way that pulls air through the radiator.  If it's pushing air through the radiator, then you're going backwards.  If you are using the alternator to spin the engine, you are spilling it backwards.

Edited November 8, 20159 yr by Cowboy

Cowboy - that was the problem ...... backwards and alternator - so was looking for overlap on regular engine barring ....... but should have been like you said.

Will check again tomorrow afternoon.

thx

Curious, wouldn't a modified camshaft do something similar depending on the cut profile?

9 hours ago, hex0rz said:

Curious, wouldn't a modified camshaft do something similar depending on the cut profile?

We were kind of thinking the same thing initially ....... my "SUPER CAM". 
But in reality don't think so - would probably have to be a change to the crank as well as then the pistons would be midway through compression or power and the vales would be opening.
So my super cam would suck for power.

 

On 11/8/2015, 9:24:45, hex0rz said:

Curious, wouldn't a modified camshaft do something similar depending on the cut profile?

Yes and no.  A cam could do that if that's what the cut profile had it do.  But it is very unlikely that they would design it like that.

We all know the typical 4 cycle sequence:  

 

Intake - Intake Valve open sucking in air.

Compression - Both Valves Closed 

Power Stroke - Both Valves Closed 

Exhaust - Exhaust Valve Open Pushing out air.

 

In a Simple World, that is how it works.  However Cam designers found they can improve the engines performance even further by changing the Opening/Closing Times.

There are many Cam profiles, But on a Cam for a 1000HP rig, The Intake Valve Stays open longer, So it's open during the beginning of the compression stroke, giving air more time to enter the cylinder at high RPM's.  Of course, this will hurt low end performance.  And likewise, The Exhaust Valve will open sooner, so it's opening during the power-stroke, this gives the exhaust more time to exit the cylinder, but you're bleeding off pressure that would otherwise be pushing the piston down and transmit power to the crank.  

You'll be hard pressed to find any cam that doesn't have just a little bit of valve overlap. As Overlap helps both High and Low RPM's.  Now there is such thing as to much overlap.  For instance If you have high drive pressure, then you'll want to minimize the overlap.  Just because you have 50 psi boost, and 60 psi drive pressure doesn't mean that overlap is bad.  There is a tremendous amount of pressure waves going throughout the intake/exhaust manifolds.  So yes the Drive Pressure is higher, But you are still benefiting from valve overlap.

All these things put together makes up part of the Cams profile, and that is why bigger isn't always better.