| MICHV8 | -- 11-03-2017 @ 9:50 AM |
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I have a tired 59AB with low compression in 5 of 8 cylinders and zero in the other 3 (1-3). I’m fiddling with it hoping the valves will free up. It runs and actually idles, but will not build any RPM with increasing throttle. I thought it might be the carb and so I switched it with another carb from a good running car and it made no difference. Is the lack of RPM just simply the low compression or should I look further?
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| Yokomo99 | -- 11-03-2017 @ 10:27 AM |
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It sounds to me like you have a few stuck valves. If only an exhaust valve is stuck the engine can run OK but with a couple of intakes stuck the blowback disrupts the airflow in the carb so the engine won't rev. I would drain the coolant and pull the heads. It is actually fairly easy to do and then you will know what you are up against. It is usually not too hard to free up the valves. To give you an idea here is a link to a video of a stuck valve being freed up on my 53 by the person I bought the car from. https://www.youtube.com/watch?v=xsFLrGOabe8 Actually this 3 video series is the reason I decided to buy this car. Scott is a pretty funny guy always gives me a good chuckle. Be sure to check out my YouTube pages at: https://www.youtube.com/user/MatthewBergin1 https://www.youtube.com/channel/UCJCdOfmXtM8xO9nXeQ-iSQQ This message was edited by Yokomo99 on 11-3-17 @ 10:52 PM
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| sarahcecelia | -- 11-03-2017 @ 5:27 PM |
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Add about a pint of marvel Mystery oil to the crankcase. It can't hurt. and sure could help !! Regards, Steve Lee
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| TomO | -- 11-04-2017 @ 7:30 AM |
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Dribble MMO down the carburetor for about 5 min, then drown the engine and let it sit for 12 hours or more. Add the recommended amount to your gas and try the engine. If you still have stuck valves, you can try to repeat the procedure. If it doesn't work the second time. you will have to pull the intake and heads. Good Luck Tom
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| supereal | -- 11-09-2017 @ 10:31 AM |
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With no compression in three cylinders at all, I would pull the right side head and see what is happening.
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| fordv8j | -- 11-09-2017 @ 3:23 PM |
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I run a 48 distributor on our 38 coupe, with a 50s type coil, I thought it was time to change coil, got one at NAPA, installed it, it would idle fine but wouldn't rev up enough to pull the car, put the old one back on it worked, took the new one back I think they had gave me one with a built in resister,my car has a resister under the dash, so wasn't getting enough fire
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| MICHV8 | -- 11-10-2017 @ 5:06 AM |
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I use the new tube type coil and bypassed the resister under the dash. It starts up in an instant, but won't rev, so pulling the head might be imminent. I am simply worried about a head bolt snapping. I only have propane to heat the bolts and that is probably not hot enough... Thanks for the suggestions.
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| shogun1940 | -- 11-10-2017 @ 5:06 AM |
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If you do a leak down test you can determine what is wrong . Basically if you put a piston on top dead center on the compression stroke and then put shop air in the cylinder it will come out where the problem is. Oil fil it is the rings. Exhaust indicates the exhaust valve, carb indicates the intake valve, bubbles in the radiator indicates head gasket or a crack inside.
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| MICHV8 | -- 11-10-2017 @ 5:09 AM |
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Is there a fitting for loading cylinders with compressed air?
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| TomO | -- 11-10-2017 @ 6:53 AM |
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You can modify a spark plug to add air or you can get a inexpensive leak down tester at Harbor Freight. https://www.harborfreight.com/catalogsearch/result/index/?dir=asc&order=EAScore%2Cf%2CEAFeatured+Weight%2Cf%2CSale+Rank%2Cf&q=cylinder+leakdown+tester Penetrating oil or a 50-50 mixture of trans fluid and acetone will free up the head nuts. I would not use heat because incorrect use can crack the block. Your choices are try MMO, do a leakdown test, just pull the intake and observe valve action or pull the heads and intake so you can determine the reason for the low and zero compression. IMHO if the MMO doesn't work, you are going to have to pull the heads to determine what is wrong. Tom
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| MICHV8 | -- 11-11-2017 @ 6:00 AM |
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Thanks all. I'll pull the intake and see how it goes...
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| MICHV8 | -- 11-11-2017 @ 6:01 AM |
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Tom() How do I modify a plug to hold compressed cylinder air?
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| cliftford | -- 11-11-2017 @ 6:27 AM |
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Take an old spark plug, break out the porecelan center, weld or braze a 1/4" pipe coupler to the sh*ll, and screw on a male air fitting that will attach to your shop air hose.
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| TomO | -- 11-11-2017 @ 6:29 AM |
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See topic https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=2967&keywords=leakdown%20test This topic was found doing a search in all forums and all in the past dates with the words "leakdown test". You can also search on "leak down test" Knowing how to search can be a big help on a lot of problems. Did you try the MMO? Tom
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| MICHV8 | -- 11-12-2017 @ 5:26 AM |
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Tom() Yes, I've added MMO to the fuel and, as you suggested in another post, a qt to the oil. I'm in the process of installing the exhaust system so I can run the engine to operating temp without headphone protection. Cold snap here in MI has delayed things somewhat!
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| TomO | -- 11-12-2017 @ 7:01 AM |
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When you get a chance, dribble about 3/4 of a pint down the carb with the engine running at a fast idle, then dump the rest down the carb just fast enough to kill the engine. Let it sit for at least 12 hours and try the engine. If you still have the problem, repeat the procedure. If the second time doesn't improve the running, you will have to pull the heads to see what is going on. Tom
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| shogun1940 | -- 11-13-2017 @ 4:12 PM |
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If you have compression tester you can remove the valve inside the end that goes in the spark plug hole and use it for a leak down tester and put it back in to do compression test
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| supereal | -- 11-17-2017 @ 9:34 AM |
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Before you start tearing down, be sure that the exhaust system is not plugged. Try a vacuum gauge. If it is stuck valves.the reading should drop 3 to 5 inches, then return. If the reading is normal ( steady at 17 to 21 inches) when first started, then drops to zero, a choked muffler or other exhaust system problem is likely. I have seen mufflers full of carbon, or loose baffles, prevent increasing rpms beyond idle, or same for a bent tailpipe.
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| MICHV8 | -- 11-18-2017 @ 4:53 AM |
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Supereal, No exhaust on the car when I started the task...now have new driver side and waiting on passenger side due next week. Still very LOUD. But thanks for the suggestion. I follow your advice all the time and appreciate your time and effort to help people like me
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| supereal | -- 11-18-2017 @ 11:42 AM |
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Thank you. I have seem mufflers so full of carbon that you can hardly lift then. It seems unlikely that many valves stick at the same time. I have seen timing gears that are badly worn skip a tooth or two and lose power. It will also occur if the ignition condenser is weak or open. I agree with my friend TomO that a look inside is probably warranted.
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