Reply to "302 Diagnosis"

Dennis. I have a 68 Shelby GT350. It is a 302. I have owned it since 1972. I don't profess to necessarily be the expert on anything, I rebuilt the engine two years ago completely into a 347.
I feel confident that I can offer you some accurate help on your situation.

A worn engine should still show a compression of no less then 125psi(cold). You should be expecting a reading of no less then 150#. A reading of around 180# is where it should be (warm).

Where is the compression going? The stock cylinder head has a non-adjustable rocker arm assembly with a positive stop stud. There are a couple of problems with it. First and formost, it only works correctly if you used the original valve train. That includes the original hydraulic lifters and pushrods. The camshaft really doesn't matter very much.

The problem is will an aftermarket lifter have the same plunger auto-adjusting range as stock?

Secondly, these are pressed in studs. There is no guaranty that with the stock springs they will stay at the correct height forever. They tend to pull out over time even with stock springs. When the valve seats are reground you change the relative height of the valve stem tip to the rest of the assembly, i.e., you have altered the geometry. The valve tip is now higher and the pushrod needs to be longer to compensate for how much the valves were cut.
The hydraulic lifter will adjust the plunger itself according to the oil pressure provided within a design limit of the plunger. In the old system this would be within 1/2 turn or the adjusting nut from zero clearance. Zero clearance would be when you can longer turn the pushrod with you fingers. That is also if the stud heights are still correct.

Your engine with that camshaft should give you stock type characteristics, namely around 18-20 in-mg at idle.

If the valves are not seating, particulary with an semi-open exhaust system like the 'goose, you will have popping through the exhaust. In all fairness it shouldn't even run and popping is an understatement. You will be at the firing range. Put on your earmuffs.

Make sure that you don't have a concealed vacuum leak under the carb like from the pcv connection under the carb, or the carb itself. You could also have a problem with an internal carb leak in the case of a holley between the metering body and the main carb body. Holleys are notorious for leaking on the pump transfer hole to the main body there.

Your problem is probably that you can't see around the engine properly because of the location of the engine in the car. This is an instance where it would be worth the extra money to pay a shop with a dyno to run the engine in on the stand. Then everything could be pre-adjusted, the engine run-in and just dropped in. Plug and play, so to speak.

Not that you need to know my preferences but I went to a solid lifter cam, screw in studs, triple spring .528 lift, 236 degrees duration @ .050 and 72 degrees of overlap. 10.4:1 cr with KB pistons. 3.4" stroke.

The lifters were pre-adjusted on the stand. Were right-on and will stay right on for as long as the hydraulics will.

With compression that low on all of the cylinders I don't think it is the valves, it sounds like something is wrong accross the board on the rings. Squirting oil into the cylinders and the compression rising up will confirm this. I hope not because that means it has to come out and come apart again.

Maybe someone else will see something that I am missing simple. Good luck, I hope it is very simple like you forgot the power brake hose.