Was wondering how much compression a fairly healthy stock model a moter should have ? This one has been sitting for many years.I had the pan off to clean it out and it appears that It has been rebuilt at some point.When i do a compression test i get about 50 lbs in all 4 cylinders,which seems kinda low.Thanks,Bob
50 Psi is kinda low IMO.I would think it would need atleast 75-80 to fire decent .Im no expert on Model A 4 bangers though.Im just speaking of engines in general here ...
I finally found the information I was looking for. Compression in a Model A should be (operative word "should") 76 PSI. Source: Tam's Model A Parts Catalog. 50 Lbs does sound a little low - maybe the valves need ground - but I'd bet it runs.
I'd suspect that it would start and run at 50 lbs. ***uming that this was checked on a cold engine? Did you put a squirt of oil in the cylinders? Good cranking speed and spun over with all the plugs out? All of these could affect compression test readings. If you ran it for a while with some fresh oil, got the rings and valve guides freed up and retested it hot, I wouldn't be surprised if it picked up another 10 lbs. of cranking compression of everything else is mechanically sound.
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