Need help with this vacuum reading

Thanks.....right now I am running 18* in park. Seems like a lot but I guess maybe not.....I will try the idea of putting it in drive and then adjusting.

But really, it runs fine at first and then slowly begins to degrade in performance...timing is still at 18* right before it dies.....

But will try it next chance.

I have no background on the engine unfortunately...It has a deep sump oil pan, an eddy performer intake manifold and 650 cfm # 1405 eddy carb with electric choke kit.....I was assuming it has a cam because of the idle....it has J heads, and is a '76 block. I was told it has a double roller timing chain......one more reason I assume it has a cam......compression was good across all the cylinders...up around 150-155 as I recall when warmed up.....pretty consistent. I have Doug;s headers on it and magnaflow exhaust kit.

I am half tempted to just say screw it and rip the cam out and start fresh....but that probably means new rods, springs, and who knows what else.....hate to throw out the baby with the bath water, but if the cam is the "problme" I could swap a milder one in.....but if its another internal issue, I wasted time and money. Thats why I am posting teh vacuum readings....hoping someone will see something.

what I need is someone who is experienced to come tale a look! ANyone in the Pittsburgh, PA area? A case of your favorite beverage to whomever can solve this problem! LOL

I have been in touch with the previous owner, a body shop, numerous times....the guy he bought the engine from was supposed to call me and let me know what was in it but seems to not want to......it wouldreally help if he did though. Wish there wasa way to trace an ENGINE to an owner...LOL

When you say "locked it out", do you mean at one particular amount of advance?

I have my vac advance disconnected and the port plugged.

So you dont think its a bad head gasket? That wild fluctuation made me think that.....