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Showing results for tags 'compression'.
Found 2 results
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I had my head milled, more than normal (.060) because I wanted to do some chamber work. I marked the gasket edge on the head and ground the area near the exhaust valves back closer to the gasket edge to unshroud the valves and did a little smoothing. Checked the resulting size and arrived at 70cc. I measured the head gasket that will be used and estimated (guessed) its' compressed thickness at .040 so it should add 8cc or so. Compression ratio = (cylinder displacement+chamber volume+head gasket volume) / (Chamber volume+head gasket volume) My numbers, all in cc's , (628+70+8) / (70+8 That puts me at 9.05:1. Close to maximum I think for a flathead. Probably be a premium fuel burner. Now the questions. How do those numbers compare to any measurements you folks have taken? Does the calculation above make sense to the collective wisdom here? There is a more smoothing that could be done to gain a few cc's if needed. edit to add: This is a 56 Plymouth 230 head. These were advertised originally at 8 or 8.1:1. With the .060 I removed they must have been way under the spec'ed ratio from the factory as the amount removed in the chamber work was not all that much.
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1949 Chrysler Windsor (C45) with flathead 6. The car sat for 12 years. Five valves were stuck open. After a few weeks of patiently working with them, I finally got them all free. Because I put so much lightweight oil (Marvel Mystery, ATF/acetone, WD-40) on the valves, I changed the oil before I tried to start it. The car is now running. Of course, it smoked to high heaven when I first started it. Now that I am past that there is a definite pattern and it is as follows: When the car is first started, the exhaust runs clean for about 7-8 minutes. Then it starts to smoke. The carb has been rebuilt. The plugs do have black soot on them, so some adjustments need to be made. I am concerned about compression. Compression is as follows: four cylinders at 80, one at 75, and one at 85. That is better than when I tested them before it was running; however, The car has had a total running time of 80-90 minutes now. If I read the manual correctly, it should be 120-150. Thoughts? Also, while working with the valves, I pulled the head. I put on a new gasket and tightened according to proper order and torque. I have attached a picture of a leak. It is the bolt the throttle linkage sets upon. I assume I need to take it out, put joint compound on it and tighten it back down. Or, is this more serious than I think? I checked my oil, it looks great! No antifreeze in oil.
