It's a fresh rebuilt Thunderbird damper with the numbers on the pulley. Plus, I used a degree wheel and piston stop to find TDC.

Ooops. Forgot. Seems like you had already mentioned earlier it was a Thunderbird damper. In that case, TDC should be reasonably close. Something else you can do is put either the #1 or the #6 cylinder with both valves at overlap equally (straight edge across the top of them so they are level) and check that the TDC on the damper is reasonably close to the pointer. It should be within 4-5 degrees and with a loose chain, possibly with the TDC on the damper being slightly past or after the pointer. This is simply a quick and dirty check for cam phasing for engines in cars without going to the trouble of doing the degree wheel / dial indicator bit.

Lorena, Texas (South of Waco)

So the timing set seems to be installed correctly.

Another thing, have you traced all of the plug wires? While #1 is typically a certain location in the cap, the installer of the wires can put #1 wherever he wants and as long as all of the wires follow the firing order and the engine can be timed, it will run just fine. So maybe the wires are not installed correctly but it is still functionally correct which is why it appears to be 180 out yet still runs.


Lawrenceville, GA

Cam overlap on all cylinders is the same, and it's about 5 degrees earlier than TDC. Also, it looks like there's about 2 degrees worth of slack in the chain. I wouldn't think that's enough to cause compression and vacuum issues. 6" of vacuum is pretty piss poor for a stock cam. I checked cylinder by cylinder per the firing order, 90 degrees at a time and the overlap followed on the cylinders per firing order. Measurements were taken with a metal ruler across the valve retainers, giving me two contact points on each valve.

When turning the engine by hand, you can hear the air blow into the oil pan pretty easily. Maybe the rings ain't as good as I hoped, but my experience doing that has been with new engines that I've built, so I'm sure they are tighter. I've not done a leakdown test yet, but I guess that will be next.

Have you checked your compression gauge for accuracy? Was the throttle opened up during the compression test? Adding oil to the cylinders and redoing the test will confirm if the ring seal is part of the problem regarding the low numbers. Your test numbers are well within the required 10% for the values between the highest and lowest so that part is good.

Lorena, Texas (South of Waco)

Ted, I was headed that direction with the compression test when the starter gave up, so I'm waiting for it to get back from the rebuilder. I did check the vacuum gauge on a known good engine to verify it, but I have not done that with the compression gauge. I will do that before my next round of testing.

Finally had time to do a cam timing check this afternoon, and here's what i came up with:

Intake valve opens at 29° BTDC vs. Ford spec of 12° BTDC
Intake valve closes at 85° ABDC vs. Ford spec of 54°ABDC
Exhaust valve opens at 89° BBDC vs. Ford spec of 58° BBDC
Exhaust valve closes at 41° ATDC vs. Ford spec of 8° ATDC

All opening and closing measurements were taken at .020" to compensate for valve lash, dial indicator inside of pushrod cup.

The intake lobe center angle came out to 112°.

Intake valve lift measured .278" (.298" - .020") vs. Ford spec of .264"

Exhaust lift measured .281" (.301" - .020") vs. Ford spec of .262"

Those look like numbers for a decent sized cam, which explains the exhaust sound and low vacuum. It may also explain the low compression pressure, if the static compression was not increased to compliment the cam.


Lawrenceville, GA

Those are 'WoW!' numbers to me! No wonder the vacuum gauge readings are L-O-W!

NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York

Yeah, assuming that I'm doing the measurements right, those numbers are way out there. But it does explain the low vacuum and compression readings, plus how far the cam has to be advanced for the car to run decently. I think that I've convinced myself to go ahead and hone the cylinders and put in a new set of rings while I have it out of the car. Not much more expense and I'll know exactly what I have.