DIY small block rebuild?

[JoeliusZ28]

Haven't done a compression test yet but its on my list. I don't have a leak down tester, is that for the head gaskets?

[MP81]

It can find a bad head or head gasket, yes, but mostly for valves or rings.

[JoeliusZ28]

This week I installed a vacuum gauge and rechecked all the vacuum hoses. Ended up finding something routed incorrectly i had overlooked before... changed it around to how it is supposed to be and its running signifiicantly better now. Actually has decent throttle reponse. On the flip side, the amount of vacuum im pulling at a cruise is still low, so I still think she's kinda tired.

[MP81]

What kind of vacuum reading are you getting at idle?

[JoeliusZ28]

18 inches. can squeeze it to 20 but thats where i get spark knock under load.

[MP81]

Ok, 18 in-Hg isn't too bad. Probably right around where I'd expect it to be...but maybe a little more? Not sure where these engines normally idle around, vac-wise.

[JoeliusZ28]

It also might just be overworked. 3.08 gears, 31s, and terrible aerodynamics probably have it working fairly hard at 70mph but it also doesnt have overdrive. Idle vacuum is ok, its what im seeing at part throttle cruise that looks low.

[MP81]

At cruise, I'd expect something closer to 10ish? I can't remember what my Cobalt does at part-throttle cruise. Something between 10 and 0 (though, granted, my gauge goes the other way too, so I'm sure that factors in).

[JoeliusZ28]

on the highway im less than 10 closer to 5. Im sure pulling a small trailer would be enough to get it to zero.