Please help me diagnose this 273

SeattleQQ1Fish said
The engine in question here is the 67 273 in my Barracuda. It has 80,000 original miles and I don’t think it’s ever been apart.

Symptoms:
-The car won’t idle smoothly under 1000 rpm. Anything under 950 and it starts to shake violently.
-The idle slowly goes up and down on its own, making it tricky to set the timing. Currently it reads 13 degrees btdc @ 1000 rpm. I can look at the balancer with the timing light and watch the timing move by itself.
-When I put the car in gear, it sputters and dies.
-A couple of the plugs I pulled out of it (I can’t remember which ones off the top of my head) were very fouled with wet oil.

Previous owner bought the car from the original owner 6 months ago. He pulled the original 2bbl and manifold to install a weiand action plus and a new 600 Holley 4160 w/electric choke. He also installed a crappy eBay distributor. He swears the car was running/driving and the timing just needed dialed in. I think he’s full of **** and decided to sell when he couldn’t get the car to run.

The car is a little hard to start, but fires up easily once it’s warm.

What I’ve done so far:
-Verified TDC on #1 with a piston stop on two different occasions.
-Timing set at approx. 13 degrees btdc at 1000rpm.
-replaced the burned up skip white distributor with a newly rebuilt 273 Commando piece from halifaxhops.
-installed a Mopar electronic ignition harness, ignition box, and a solid state VR and coil from Standard. Plugs and wires were replaced.
-backed out both screws on the carb, squirted in carb cleaner and blew it out with compressed air.

Nothing so far has helped at all, and it keeps getting worse. Just did a compression & vacuum test:

Compression Test:
Cylinder
1 - 65/75
3- 130/125
5- 105/105
7- 80/80
2- 105/115
4- 115/115
6- 120/130
8- 105/105

Vacuum:
It pulls 15 at 1100 rpm, 14 @ 1000, 12 @900 as the engine shakes and dies.

I’m not sure how to interpret vacuum readings, but I assume the compression test means the heads need rebuilt. Can anyone offer some insight?

Adjust the valves and redo the compression test...

Here's a good link to help you understand and interpret vacuum readings:

Vacuum Gauge troubleshooting

I would also recommend changing the timing chain... Those old nylon coated gears on the 273/318 were junk... The nylon gets old and brittle and chips off, causing a loose chain, and can even allow the chain to jump a tooth... It will also cause your timing to jump back and forth and making it difficult to set the timing... I changed the chain on a 68 318 with 80 k miles to a double roller and gained 2 MPG it was so sloppy....

Installing a new good quality double roller timing chain and gears will make your timing more consistent and your idle smoother and vacuum reading smoother and more steady...

I've run this chain for decades in all of my engines and they hold up great... It's a true roller double roller timing chain one step above the stock 340 chain... I put one in an engine and ran it 125,000 before refreshing it up, and this chain was still in good shape... I replaced it with a new one anyway because I got it for $50 bucks back then and it was worth the piece of mind to have a new one...

Here's the chain that I use....

Edelbrock Performer-Link True Roller Timing Chain Set

Here's what the original timing chain gear can look like after 50,000 or more miles....

DSC01942 B.JPG