71455GS
By all means, get an oil pressure guage and install it where the sending unit is on the block
Remove all the plugs and do a compression test
remove the valve covers and, while cranking the engine over, watch each rocket arm/valve to see if they are all opening and closing. watch to see if oil is coming out of each passage. I use the air compressor to blow them out
if the compression is equal on all eight cylinders (my 455 is between 130-150) BUT, it had been sitting on a barn floor for 5 years, and I had to free up a couple of lifters (I used penetrating oil & Mystery Oil, needed a ball peen hammer on a couple of them). I had it turning freely BEFORE I put sparkplugs in it.
If the oil pressure is real low, check the pressure release valve in the oil pump, make sure it slides freely.
You are going to have to change the oil again because of the penetrating oil and the gunky oil that you have forced out of the passageways.
If you have a 71GS w/455, take your time, we wanna see that baby back on the road
Butch
64Wildcat 445
64 LeSabre 300
73 455 on bench
67 Impala 327
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