64 Dart 273 Engine Vacuum
I am sure they have the cam timing off and will need to pull the engine,
I wouldn't jump to that yet.
I would;
1) reset the valve lash as already described
2) do a proper compression test with a fully charged battery and all plugs out, with the throttle more or less at WOT. If the engine runs, then warm it up first.
3) prove the balancer TDC mark is true TDC of the #1piston using a piston-stop, and re-index it as may be required, then
4) make sure the vacuum advance is NOT plumbed to full-time manifold vacuum
5) install a NEW PCV valve on a proven to be good hose
6) reset the idle-timing to in the range of 8 to 10 degrees
7) set the idlespeed to 650/700 in Neutral
8) reset the mixture screws for best idle
9) Prove that the only air the engine is getting, is passing thru/past the throttle valves.
10) now, you have eliminated about 90% of the cause of a low idle-vacuum, in your case only the cam is left, and maybe the CCP.
As for me, I would not care what the idle vacuum might be at this point.
But if you think it is still low, and the engine does not have a pronounced idle-lope, then you might like to check the cam timing. BUT, you do not have to take the engine out to do this.
and there is a shortcut, which on a solid-lifter engine is pretty easy. You just go find Split overlap on #1 cylinder and if it is within the range of 4*advanced to 2* retarded; forget about it. Save yourself a lotta work.
Notes;
TDC is Top Dead Center
WOT is Wide Open Throttle
CCP is Cranking Cylinder Pressure.
Split overlap should always occur within a few degrees of TDC, on the switchover from the exhaust stroke to the intake stroke; no matter what size the cam is. Almost 100% of the time the cam will be in slightly advanced. You can read the amount, right off the proven balancer. Easy peasy. The best time to do this when you are adjusting the valves. The cam-chain should be reasonably tight. You are only looking for a gross error. Theoretically, the valve-lash on the cylinder to be tested, (usually #1 but could be #6) should be reduced to zero, prior to checking, then restored afterwards. But you can do a quick-test without doing that, and be close enough to tell if the cam is out a tooth. This will not be accurate with a sloppy chain.
IMO, Your CCP at your elevation in NY should be close to or over 140psi on an original 2bbl engine, more on an original 4bbl engine.
