* Specific engine: Even within the Vortec V6 family (which had variations across the S10's production years), there are differences. The exact specifications are in your owner's manual or a service manual for your specific engine code (found on a sticker on the engine itself).
* Engine wear: As an engine ages, compression naturally decreases. A slightly lower-than-ideal compression reading doesn't always mean a major problem, particularly if the readings are relatively consistent across all cylinders.
* Testing conditions: Ambient temperature and the testing procedure itself can impact readings.
Instead of looking for a single "correct" number, you should be looking for *consistency* across all cylinders and comparing against a *range* specified in a repair manual for your specific engine. A significant difference in compression between cylinders points towards a problem (like worn rings or a valve issue).
To find the correct information:
1. Locate your engine's code: This is usually a series of letters and numbers cast directly into the engine block.
2. Consult a repair manual: A Haynes or Chilton manual for your specific year and model S10 will give you the correct compression specifications and testing procedures. A factory service manual is even better, but more expensive.
Without this specific information, any compression number given would be unreliable and potentially misleading.
