| Bill Cox | -- 10-31-2011 @ 10:29 AM |
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Is it possible for the camshaft to be 180 out of time and cause low compression on all cylinders (30 to 50 lbs) Dist and wireing is all right getting spark to all cylinders in the correct order at the top of the compression stroke, Getting gas but will not start, wont even pop or back fire
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| carcrazy | -- 10-31-2011 @ 12:26 PM |
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It is highly unlikely that the camshaft would be 180 degrees out of timing if the engine previously ran OK. Have you tried using starting fluid (ether) to see if you can get the engine to fire-up and run?
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| bonusbuilt1950 | -- 10-31-2011 @ 12:44 PM |
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Are getting a good blue spark when you check? THese flatheads need a real good spark. You can try silicone spray as starting fluid. Not quite a volatile as ether, but works well. You need 3 basic things... air, fuel and spark. Make sure you have all 3 and it should fire. With that low compression, you could put a little oil in each cyl to see if that would raise the compression some. I had a flatty a few years ago with 45-50lbs and that thing never did start. Good luck, Barry 50 F-1
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| Stroker | -- 10-31-2011 @ 2:11 PM |
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Given the relationship between the crank and cam 2:1 ratio, having the cam "180 degrees out of time" would have no effect, and the engine would, in fact, be "in time", the next time the crank made a revolution. Having said that, being just one tooth off can dramatically affect compression, but then your timing would be either dramatically advanced or retarded.
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| Stroker | -- 10-31-2011 @ 2:11 PM |
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ditto This message was edited by Stroker on 10-31-11 @ 2:27 PM
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| supereal | -- 10-31-2011 @ 3:13 PM |
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If the drive tang of the distributor is matched to the groove of the camshaft, it is virtually impossible to put the engine out of time, and still bolt the distributor into place. I'd bet that your spark plug wires are not properly installed. Remember that the cylinders are numbered beginning on the passenger side, as 1-2-3-4, with the driver side as 5-6-7-8.
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| ford38v8 | -- 10-31-2011 @ 6:20 PM |
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Dan, If I understand what you are saying, then I must disagree. If the flathead were a two stroke, then your theory would be correct. A four stroke, however, has the piston at TDC twice for every cycle. 180ยบ out would fire on an empty cylinder. I think I understand what I wrote! Alan
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| TomO | -- 11-01-2011 @ 8:02 AM |
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Bill, Take the spark plug out of the first cylinder on the right side of the car (left and right determined by sitting in the car). Place your thumb over the hole and tap the starter until you can feel the compression stroke. Then remove the right side distributor cap and look at the rotor rear arm. It should be near the 11 o'clock position. If it is, your distributor and camshaft are pretty close in time with the crankshaft. To be sure you would have to find TDC of Cyl 1 and then retard the distributor timing, turn on the ignition switch and move the timing screw to the advance position while observing the spark at No1 cylinder. The other way is to remove the timing cover and make sure that the lines are aligned when the piston is at TDC. 30-50 lbs compression is pretty low. Things that I would check are: Battery - is the starter turning over the engine fast enough? Are all of the plugs out and the throttle open all of the way while doing the compression test? Did you try adding about a tablespoon of oil to one of the lowest reading cylinders to see if that made a difference? Has the engine been rebuilt recently? Has it run in the past few weeks? The rings could be stuck or you could have sticky valves. Tom
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| Stroker | -- 11-01-2011 @ 10:58 AM |
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Alan: I'll confess that my "explanation" was misleading. What I meant to emphasize was the fact that the timing gear is by design oriented correctly to the cam, and likewise the distributor is made so that it cannot be assembled 180 degrees out of time with the cam. If one were to observe the timing marks when Number 1 piston is at top dead center on the exhaust stroke, the marks will be "180 out of time". The pistons don't know which stroke they're on, only the cam does. If at this point, I removed the timing gear, and rotated the cam 180 degrees, re-installed the timing gear so the marks lined up, I haven't changed a thing.
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