Compression specs, what's the acceptable range?

[Jim2]

I just checked mine, and it looks like I have a couple cylinders that are out of the 10% range.. the highest was 178, but one was 149, and one was 153.

* I forgot to open the throttle when I did the test * (but had the engine at 180-195 degrees throughout the testing.)

My truck has no power, especially down low.
The vacuum test looks like it's bad rings..

 

[adsm08]

That is a hair out of spec, but what were your vac readings?

It may be a plugged cat too.

 

[Jim2]

the vac holds steady at 17... jumps to about 20-21 after opening it up.

there's no cat. but it's got headers and oversized exhaust ... that's why I want to try that bigger throttle body that's up for sale.. thanx..

 

[Jim2]

Here's a vid from last week at the track. It bogs when going from first to second, and can't wind up second gear. After a while, I decided to just try to get good air off this one jump. http://www.youtube.com/watch?v=fROSDfbGUxg

 

[Jim2]

That is a hair out of spec, but what were your vac readings?

well, a vid is worth a thousand words...

http://www.youtube.com/watch?v=d5Z99P-bqTI

When it drops, @ 0:14, I didn't touch anything yet. The engine was running for about 30 seconds before the vid starts... not warmed up.
It recovered by itself, I didn't touch the throttle until 0:27.

When I punch the throttle, it pops. Today was first time it popped 4 times (@ 0:39).. usually, it only pops once.

If you have any suggestions about something else to check, I'm all ears.. thanks!

[edit to fix the vid link, wrong link at first]

 

[Jim2]

That is a hair out of spec, but what were your vac readings?

When you say it's only a hair out of spec, I hope that means it should be able to run much better than it does..?

There's so many things to check, I don't know where to look next.
I cleaned the IAC.
Cleaned both ends of the battery positive cable.
New battery ground cable.
Replaced the cracked heads.. all new gaskets, bolts, etc..
Set the timing according to spec.

The compression test results; (but I forgot to open the throttle)

#4=153......#1=171
#5=165......#2=149
#6=172......#3=178

Here's that vacuum test vid again (sorry I posted the wrong vid at first). http://www.youtube.com/watch?v=d5Z99P-bqTI

FWIW, here's more details..
When I got this truck, it already had an "Accel 300+" spark box, headers, and oversized exhaust.
There was no cat on it, and I cut the tailpipe off (after the muffler).
It has a cone air filter too.. but even with the filter off, the hesitation is still there.
The brake booster is disconnected, and that vacuum line has been plugged.

Any suggestions on what to look at next?