In addition, pull all the spark plugs. You are testing one cylinder at a time and you don't need the drag of the other 7.Is it the original engine for the car? Do you know how to identify a polysphere vs LA 318? You haven't said much about your experience or history with this car - have you had the engine running, or has the engine run at some point in the past week, month or year?
To prepare for a compression test, you need to have the battery fully charged. If the battery is weak or old you may need to charge it up during the test. The battery needs to turn the engine crank at a consistent speed for all cylinders. Hold the throttle plate open and stick a screwdriver down the carb to hold it open during the test. Disconnect one of the wires at the spark coil (one of the the low voltage wires). Don't let the loose wire touch anything, tape it up if necessary. Remember that all the spark plugs come out first before you start testing.
If the engine has been run in the past week then I think you can do a cold test without spraying any oil into the cylinders. I've gotten good numbers on my 318 (LA block) doing a cold test. You only want to do 4 cranks, you'll see the needle jump each time, with not much difference between the 3'rd and 4'th crank. The 3'rd crank should get you over 100 psi. If you have 130+ PSI on 4 cranks, call it a good result. The absolute best you could see is 150 to 160.
When connecting the compression-tester hose, just screw it in and finger-tighten it, don't use any tools. It should have a big o-ring on the threads to seal it.
I can't just do it one at a time? Is there a benefit to pulling all of them at once?In addition, pull all the spark plugs.
Do the valve covers look like this? If so you have a Poly 318 and not a LA. It doesn't matter really. Just curious.It's a Canadian car. Original engine. It runs and drives (however, not very well, due to the fact that it was on a farm for the past 12-15 years or so). It was running about 2 months ago. Also, I don't know how long that gas has been in there. Before I replace/ rebuild the engine, I'd like to see how she runs with newer gas, and after a compression test.
I am not a mechanic, but it comes to these kinds of things, I'd like to be as knowledgeable as possible. For example, I did not know that the battery had to be fresh, and I thank you very much for letting me know that part.
Just so you know, I think this forum is awesome, and everyone on here is just wonderful. Thank you so much for all the help, and all of the details you've given me. If there's anything else you can think of, please let me know, I would GREATLY appreciate it.
Maybe... They're pretty rough. I know that the distributor is at the back, against the firewall (if that makes a difference).Do the valve covers look like this? If so you have a Poly 318 and not a LA. It doesn't matter really. Just curious.
View attachment 630030
I will check the valve covers sometime today or tomorrow, and get back to you. Thank you again for all of the support!Having the polysphere in the car will tell you (and us) that this is almost certainly the original engine. If the lower edge of the valve cover is wavy then it's a polysphere.
Yes you take out all the plugs first, then screw the tester into each spark plug hole. Then when you're done you put all the plugs back in. You want the engine crank to spin at a good clip during the test, and to not drain the battery while you're cranking. The engine will turn very freely without plugs.
It's too late now, but you should have fully drained that old gas out before running the engine. And you should have changed the oil (you didn't say if you did or didn't).
The Poly valve covers have the scallop at the bottom. Obvious for sure. The only Mopar ones like that.Maybe... They're pretty rough. I know that the distributor is at the back, against the firewall (if that makes a difference).
Don't be in a hurry to rebuild/replace the engine.It's a Canadian car. Original engine. It runs and drives (however, not very well, due to the fact that it was on a farm for the past 12-15 years or so). It was running about 2 months ago. Also, I don't know how long that gas has been in there. Before I replace/ rebuild the engine,
I'd love to be able to test it for a few thousand miles, but, it's winter time here, and I don't know if I'm going to be able to be driving around that long. The idea was, the restore this guy over the winter, then drive it in summer. Anything else I can try?Don't be in a hurry to rebuild/replace the engine.
Get it running and put several thousand miles on it at all speeds then assess the condition of the engine.
I'd love to be able to test it for a few thousand miles, but, it's winter time here, and I don't know if I'm going to be able to be driving around that long. The idea was, the restore this guy over the winter, then drive it in summer. Anything else I can try?