It sounds like the timing is off. Check to make sure that the engine didn't jump time or break the timing belt.
What is the cylinder compression on a 1991 Ford Ranger with a 2.9?
any where from 120 lbs to 180 lbs
Stihl web page lists minimum as 110 lbs of compression
125-130 lbs
You will have to do a compression test yourself to know that. A engine that is in good shape should have at least 150 LBS. per cylinder. There can not be more then 20 LBS. difference in any cylinders. It has to have at least 100 LBS. for the cylinder to fire at an Idle.
If it's in good shape, Then all cylinders should read about 150 LBS. Less is okay as long as all of them have no more then 10 LBS. difference between them. If the compression is less then 120 LBS. then the engine has valve or pistion ring problems.
about 12o lbs per cylinder
your answer is not easy. do you want ratio or compression pressure. I would guess you are talking pressure, which on a stock engine is around 155 lbs.
That engine FRESH / NEW should have 150 LBS. compression per cylinder. If you have more then 20 LBS. difference in any cylinder then it is not in good shape and a good VALVE JOB is probley in the furture.
That number can vary, what you want to see is the compression reading on all of the cylinders within 10 - 15 lbs of each other.
Anything above 125 LBS. is fine as long as there is no more then 15 LBS difference in any of the cylinders.
There are 16 ounces in a pound