Welcome to "Ed's mystery motor, post #gazillion".
Those of you who have been following along know this is a mystery 440 in my '68 GTX.
The latest was I installed a mechanical oil pressure gauge; since I've heard some rather scary rattles in the engine a couple times under hard acceleration, I also presumed that the mystery chrome dipstick in this thing might be off and added a quart of oil to what I think was already 5 (stock pan, I think).
When I fired the car up to test the gauge, it warmed up as usual seemed like. I goosed it several times to watch the gauge for operation and then all of a sudden...
it wouldn't idle and ran pretty rough. I had to keep my foot on it to keep it running. Idle dropped from 800RPM to less than 500RPM, like it had dropped a cylinder or skipped timing or something.
As I continued to try to "clear its' throat", it would sometimes seemingly hit on all 8 and smooth out for a moment, then go back into grump mode.
If I held throttle to around 2000RPM, it would grumble grumble grumble
hit on all 8 grumble grumble
hit on all 8 grumble grumble.
Intermittent, like that.
-Recent compression test showed 130 across the board, give or take a couple pounds (yep, they're all that close).
Previous owner, long deceased, built this engine out of what looks like a '75 block with the original '68's internals. I have pretty much replaced ALL ignition, fuel and cooling systems on this car (and I mean
ALL). It also has a newer fairly mild Comp Cams and lifters in it.
Typically, the engine runs well enough and I've put probably 6-700 miles on it since I've gotten it back on the road this summer.
Here's the spark plug pic:
View attachment 352314
They're the usual Champions with just a few hundred miles on them.
I don't see anything to warrant concern here. If there was anything drastically/mechanically wrong, they'd show it, right?
Y'all know a bunch more about this stuff than I do. All I know is right now, after all this work, my baby is a beached whale in prime summer cruising months!
HELP!!