I have what is essentially a junk yard LS1 bottom end out of a 2002 Camaro. It was disassembled and inspected, with the rotating assembly rebalanced, and then reassembled with new piston rings. I bought it as a short block for a few bucks and a 4.8 in trade. It has a set of mildly ported 243 heads, a mild cam, comp trunion upgrade and springs, and Im running an MSD 6010 box and a Holley 650 double pumper.

After a small issue with the oil pump (no damage to anything), it fired right up and settles in to a decent idle at 900-1000 RPM with zero tuning thus far and open headers (going to the exhaust shop on THRS).

My question is the temps at each header tube....

CYL 1 - 197 degrees
CYL 3 - 255 degrees
CYL 5 - 249 degrees
CYL 7 - 230 degrees

CYL 2 - 201 degrees
CYL 4 - 229 degrees
CYL 6 - 238 degrees
CYL 8 - 185 degrees

Any input as to why the spread in temps exiting each cylinder? Again, there has been no tuning done thus far, and the headers are open, it just seemed odd to me.

Any input is much appreciated!

 

additionally, Im relatively certain that the low temp cylinders are in fact firing because the plugs are just as black as the others (she's running pig rich at the moment)