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Discussion Topic:
1953 Ford V8 low compression
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1953fords |
03-29-2019 @ 4:53 PM
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Member
Posts: 28
Joined: Oct 2010
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Trying to get rebuilt flathead running but have one problem after another. Now the compression is low in all cylinders. Adjusted the number 1 cylinder intake and exhaust but only brought the compression up from 20 to 60. All the cylinders are reading low around 20-30 and only on had a reading of 56-58. What could be wrong after valves in number one is adjusted? Could the rings be next?
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40cpe |
03-29-2019 @ 5:01 PM
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Posts: 475
Joined: Jan 2010
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Are you sure the the crank/cam dots are aligned?
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pauls39coupe |
03-29-2019 @ 6:15 PM
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Member
Posts: 205
Joined: Jul 2014
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Who did the rebuild? Were the valves ground and lapped? Were the valves all good or were some bent or burned?Were the cylinders bored and if so were the correct oversize pistons installed? How much gap did the piston rings have? If you adjusted #1 valves and the compression came up I would suspect the other cylinders would do the same. Be sure the cam and crank gears are aligned properly and the the valve clearance is set correctly on both the intake and exhaust. Be sure the heads are torqued properly, and that the intake gasket is installed properly. Assuming the compression will come up if the valves are adjusted properly, the engine should start with 60 lbs of compression. Then it may need to be run to break in the rings, which will raise the compression more. Please give us some more information about how the engine was rebuilt,
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mfirth |
03-30-2019 @ 4:39 AM
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Member
Posts: 208
Joined: Nov 2017
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A year ago i got a new Mellings cam gear and the "dot" was in the wrong place ! Had to degree it in or timing would be off....just say'n. mike
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1953fords |
03-30-2019 @ 5:30 AM
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Member
Posts: 28
Joined: Oct 2010
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This engine was partially rebuilt. I did the rebuild. Put new rings in and new seals. Engine looked like it was rebuilt before I got it. This was all done about 14 years ago. I just put the engine in the car in 2017. My son, a mechanic, did a victoria for me and that one ran good. I just got new seals and rings. I really don't remember what I did because it was too long ago. If I get all the valves adjusted and all come up to 60 or better you say it would run? I added oil to pistons and the 60 went to 90. This engine has sat on the stand for 14+ years and the rings and seals may be old now. I did turn it over every couple of months on the stand. I don't know what else to tell you and I hate to take the engine out again.
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pauls39coupe |
03-30-2019 @ 8:47 AM
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Member
Posts: 205
Joined: Jul 2014
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Did you hone the cylinders before installing the new rings? If not it may take a while for the rings to conform to the shape of the cylinders. I would adjust all the the valves to see if you can get the compression up around 60 or better, then fire it up. It should run, but don't expect the best performance unless you tear the engine down and do a complete rebuild. Oiling the cylinders indicates they are not sealing well. You should change the oil and filter after an hour or so run time to remove any loose metal shaving as the rings and cylinder walls wear together. Paul
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37RAGTOPMAN |
03-30-2019 @ 9:08 AM
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Senior
Posts: 1962
Joined: Oct 2009
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hi 53 ford it seems odd to me that from sitting you would have lost compression, sticking valves open are what I would look for first, use a light and see if you can see them going up and down, I use my thumb in the spark plug hole to see if it has any compression,after adding oil to the cylinder, did you try a few different compression testers, just a thought, ? also open the throttle plate in the carb and remove the air cleaner,then take compression with all spark plugs removed, and make sure the exhaust system it not blocked up, like a mouse nest, if you have too remove a pipe to see there are nothing wrong with it, if it can nothing can go out nothing will come in, try oil in the cylinders , do a wet compression test, if the compression comes up, maybe the rings are stuck from sitting ? doing a leak down test is next, I would try get it running, this most likely what it needs, loosen everything up let hear how you made out, my 2 cents 37RAGTOPMAN
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1953fords |
03-31-2019 @ 11:32 AM
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Member
Posts: 28
Joined: Oct 2010
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looks like the valves were set ok...removed heads and checked according to manual. Found out the bore is 3 3/16 which they told me is about an 80 ring size and I put in 10 rings. Didn't know that it was bored out when I took it apart and I am not a mechanic to know that I should have measured the bore. I guess that's why most of the compression test were around 20-28 and only one piston (8) had a 58. Sounds like I put in the wrong rings???????????????????????????????????????????????????????????????????????????????????????
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pauls39coupe |
03-31-2019 @ 4:41 PM
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Member
Posts: 205
Joined: Jul 2014
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I assume you are working on a 1953 8BA type flathead. The stock bore is 3 3/16 (3.1875). .010 rings would not fit unless it was really worn out. Time to get someone with an inside mic, to see what your bore actually is.
This message was edited by pauls39coupe on 3-31-19 @ 4:42 PM
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1953fords |
04-01-2019 @ 4:22 AM
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Member
Posts: 28
Joined: Oct 2010
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If the rings are to big wouldn't that be the problem that they are not gaped correctly which is giving the low compression readings?
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