Re: Normal Compression Test Values for 1931 Super 8
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Good morning.I agree with Gary. The cause may actually be that the car was not driven regularly. You do need to remove the head and valve covers and inspect. Another problem we see. Over and over is starting these engines with old fuel. They sometimes do start, but leave varnish everywhere, and when it cools and hardens, the engine becomes stuck. You need to do this work correctly. Attempting to save money usually means you will pay twice, unfortunately. Good luck. Ernie in Arizona
Posted on: 2022/5/18 9:22
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Caretaker of the 1949-288 Deluxe Touring Sedan
'Miss Prudence' and the 1931 Model A Ford Tudor 'Miss Princess' |
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Re: Normal Compression Test Values for 1931 Super 8
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Static compression is cranking compression. Dynamic compression is with the engine idling, which always is lower, unless those labels are wrong of course.
The variation isn't so hot either and I would expect that should be fixed as it is poor enough to affect idle quality and cause overheating. Freeing up the valves can be done with the valve cover off and a pair of water pump pliers if you are lucky, but only is a temporary fix. Running Gumout through the thing might help a little. The least expensive route is pull the head, take out each valve, and polish the stems with crocus cloth or whatever. Clean the guides out, clean the oil pan, crankcase, and start running Risolone with detergent oil.
Posted on: 2022/5/18 10:55
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Re: Normal Compression Test Values for 1931 Super 8
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Just can't stay away
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I hadn't noticed the "Dynamic Compression" label, and I'd assumed it was typical static compression test results. Thanks for pointing out the difference. Yes, I think I'm going to have to pull the head and valves.
Posted on: 2022/5/19 9:33
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Re: Normal Compression Test Values for 1931 Super 8
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Looks like a valve in each of cylinders 4 and 6 is stuck open- can't visualize cylinder 2 in the photos I took, but compression test readings in 2,4 and 6 cylinders were zero dry and wet. Exhaust or intake valve?
Posted on: 2022/5/19 13:35
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Re: Normal Compression Test Values for 1931 Super 8
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Lots of WD-40 and PB Blaster with some gentle tapping of the top of the valve through the spark plug hole freed up stuck exhaust valve in cylinder 6. I'm soaking the remaining exhaust valves (2 and 4) and hopefully will free them up as well. Fingers crossed!
Posted on: 2022/5/27 9:53
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Re: Normal Compression Test Values for 1931 Super 8
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Home away from home
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Great news. Since you can get to the valve ends you could try rotating the valve with some pliers. Just another thought
Posted on: 2022/5/27 10:01
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Re: Normal Compression Test Values for 1931 Super 8
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Good idea- thanks!
Posted on: 2022/5/27 15:31
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Re: Normal Compression Test Values for 1931 Super 8
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Here’s a quick update on my valve and compression situation. Over a period of several weeks, I’ve been squirting generous amounts of penetrating oil, WD-40, Gumout and Marvel Mystery oil around the valves through the spark plug hole. Initially, exhaust valves in cylinders 2,4 and 6 were hanging up. Cylinder 6 valve popped back down with gentle tapping on the valve head through the spark plug hole. Same with the valve in cylinder 2. Number 4 exhaust valve has been stubborn- didn’t budge with vigorous tapping through spark plug hole. Finally after several rounds of lubrication oils it finally released- still hangs up, but with a gentle tap , it pops down. I’m continuing to work it periodically and it is improving. Also, I’m starting to get some compression in cylinder 6.
Here is today’s video of a portion of the valve train in action. The far right valve is troublesome yet improved #4 exhaust valve- starting to show some limited movement and easily springs back in place with gentle tapping. youtu.be/hy1mKJDtv20
Posted on: 2022/6/26 20:25
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Re: Normal Compression Test Values for 1931 Super 8
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You really need to take the cylinder head off and remove those valves because sticking valves can damage the roller cam followers. And while the head is off check the seating given they are being tampered with.
I remember Billy Hirsch had this car with sticking valves. He spent all kinds of money on it but didn't do anything with the valves because they weren't sticking when cold. As soon as he took it out the valves stuck. It was hilarious because he was like Trump - he refused to accept the facts. It was all my fault. I laughed when he said that.
Posted on: 2022/6/26 21:32
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