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Discussion Topic:
tired 59AB...no RPM increase
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MICHV8 |
11-03-2017 @ 9:50 AM
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Member
Posts: 450
Joined: Jul 2010
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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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Posts: 52
Joined: Oct 2017
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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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Senior
Posts: 1193
Joined: Mar 2013
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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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Senior
Posts: 7256
Joined: Oct 2009
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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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Senior
Posts: 6819
Joined: Oct 2009
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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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New Member
Posts: 176
Joined: Jan 2015
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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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Member
Posts: 450
Joined: Jul 2010
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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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Member
Posts: 464
Joined: Feb 2010
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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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Member
Posts: 450
Joined: Jul 2010
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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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Senior
Posts: 7256
Joined: Oct 2009
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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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