Hello. I have a 53 Plymouth Cranbrook with a Hydrive 218. I finally got it running and driving decently (its been sitting for 30 years) so now I'm checking over things to make it more dependable. Do you guys know how much psi I should have per cylinder? I did a quick search and wasn't able to find anything. I have yet to check how much I actually have. I was planning on doing it this week. I'm new to flatheads so sorry if this is a dumb question. Thanks in advance for the advice.
You "should" have somewhere around 80 or 90 pounds, but I have had lots of those old girls that would barely bump a gauge and they ran fine. You want to drive it for a while before doing a comp test, let it loosen everything up if it sat for 30 years.
Thanks. Ive driven it a decent amount since I got it running. Ill check it out this weekend or early next week and see how it is.
Compression ratio 7:1 so compression pressure should be 100 pounds, more or less. If all cylinders are within 10% of each other and above 80 pounds you are in pretty good shape. Oil pressure 45PSI @ 30 MPH These engines are foolers. They will continue to start and run with no bad knocks or bangs in an advanced state of wear. The only symptoms are hard starting, bad gas mileage and no power. If you have bad oil pressure and bad compression, try a ring and valve job or in extreme cases rebuild the engine, you will be surprised how much better it runs.
remember your transmission is piped to and uses engine oil. An oil change requires about 10 quarts give or take.