Compression Test- Hot vs Cold

The Factory Service manual lists that cranking compression on a 440 should be 110-150 with the engine warm. I have headers and my plugs aren't too hard to get out and in, but with the headers hot (which they will be while the engine is warm) its impossible not to burn my hands or arms, even if I wear gloves. I tested mine just for giggles, and got 125-130 on all cylinders, how much higher do you think it would be hot?

I cannot answer that question, but the real issue is how far apart the highest and lowest cylinders are. If the highest is around 130 and the lowest is around 115, you are in good shape. Many newer repair manuals will state that the ACTUAL numbers can vary, but the goal is for the engine to have less than 10% hole to hole variance . Naybe the hot readings are higher due to piston expansion. Either way, If the engine idles smoothe and doesnt smoke, you have a winner.

Did you pull all the plugs for the cold test? A hint... you can remove spark plugs with a 13/16 box end wrench too, and/or pull the two motor mount to K frame bolts and jack the engine up a little to help access to the plugs. The engine will stay warm for the few minutes that takes. If you changed the cam the pressure recommendations from the FSM are not valid any way. I'd expect with things hot and all the plugs out it would pump 10-15% higher depending on the quality of the ring seal.

I had another comment. Regarding HOT vs COLD... the engine can be warmed up to operating temperature , then shut off and let to cool for a half hour. The headers will cool enough to allow plug removal without melted flesh. My 70 Charger has 2" TTI pipes, and I know how difficult it is to remove the plugs when the engine is warm. ODDLY, the pass. side is the pisser. #2,4 and 8 are much easier to reach from underneath. With your engine cooled down enough to touch, it will still be at an acceptable temperature for a hot test.

Just a note, prop the carb wide open so you get plenty of air while cranking, it does make a difference.