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Discussion Topic:
Stumbly 36...carb??...or ign??
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Grant |
08-09-2014 @ 8:29 AM
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Senior
Posts: 535
Joined: Oct 2009
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Yesterday, as a final step in preparation for the Central National Meet, I decided to take our '36 for a 75 mile test run on the highway. After about 15 miles at 55 to 60 mph, there was a noticeable stumbly hesitation developing, like an on and off surge. At first it seemed to go away with acceleration. But bit by bit the recurring hesitation got worse. The problem does not appear to be vapor lock. At the halfway mark, before turning around to head for home, I disconnected the gas feed line to the mechanical fuel pump and ran the vehicle hooked up solely to the electric unit (Airtex E8902 6 volt low pressure ... mounted under the left running board with a protective cover ... operates off a switch under the dash ... normally used only as back-up on a hot day). The issue continued to deteriorate. I barely got up the big hill in the last half mile to our house. Accelerating from a stopped position, this '36 is now chugging like a 9N tractor. Second isn't as bad, especially in the top half of the rpm's in that gear, but after shifting into third there is near-zero capability to continue accelerating. This morning I checked the wire connections at each spark plug. They are fine. Then I removed the top of the carburetor (model 97). The float seems to be okay, and the inside of the carb looks pretty clean. Next I started the engine, and backed out of the garage. It was idling roughly, and the sound of the exhaust is badly wrong. Turning in both adjustment screws a bit (about half a turn) resulted in a better idle at slightly lower rpm than before, but the engine is just plain gutless going up and down the driveway .......... almost as if there are several dead cylinders. Overheating did not occur. Yesterday, as soon as the car was parked, I went into the house and got a meat thermometer. Coolant in the radiator was at 188 degrees. The under-dash SW heat gauge showed 182. So what hath the flathead gods wrought this time ??? Has an ignition malfunction somehow magically developed literally overnight? This '36 ran fine Thursday afternoon on a two mile return trip into the local village. Or instead, could there be some sort of fuel delivery issue inside the carburetor? I am discouraged, to put it mildly, and have no idea how to diagnose this one.
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fenbach |
08-09-2014 @ 8:35 AM
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Member
Posts: 227
Joined: Dec 2009
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condenser maybe? or coil? both fairly simple to swap out. or point gap? easy to check with a dwell meter.
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JM |
08-09-2014 @ 10:12 AM
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Senior
Posts: 822
Joined: Oct 2009
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I agree with fenback. Sounds just like my '35 ran at one time. The more I tried to drive it the worse it got. Just barely made it home. The problem was in the distributor. Condensor and poor quality points. Points were burned and pitted. Rebuilt another distributor with a set of good quality points, replaced condensor, and installed a new rewound coil by Skip Haney. Has run perfect now for the last 10k miles.
John
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supereal |
08-09-2014 @ 2:18 PM
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Senior
Posts: 6819
Joined: Oct 2009
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I also suspect the condenser. If it has gone open, it is likely the points will need to be replaced. I carry a spare condenser in my road kit. It is fitted with clip leads, and can be substituted by putting it between a ground and the input to the coil. Years ago, it was fairly rare to have a condenser failure, but today's are often poor, even when new. The condenser serves two purposes: to minimize point arcing, and to form a circuit to allow fast charge and discharge of the coil. If your coil is original, it should be rebuilt or replaced before you take a long trip
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Grant |
08-11-2014 @ 8:35 PM
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Senior
Posts: 535
Joined: Oct 2009
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Thank you, gentlemen, for your responses. This vehicle came with a supposedly rebuilt distributor assembly as a spare. It was kept in the rumble seat compartment, and intended for use if repairs on a trip became necessary. Today I removed the old distributor and installed the spare as a replacement. The work took 6 1/2 hours. The engine now no longer runs at all. There is no spark at the plugs. Another club member was on the phone earlier this evening, and advises that the best approach will be to send the entire unit away for rebuilding. I think he is likely 100% right. Has anyone out there recently had an early V8 distributor like the one in our '36 re-done by a trustworthy rebuilder? I would like to deal with a reputable professional shop that has a KRW fixture ...... or similar equipment ...... so that the newly rebuilt unit can be properly timed and fully set up, ready to install, before it is shipped back here.
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joe b |
08-12-2014 @ 6:03 AM
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Member
Posts: 389
Joined: Oct 2010
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Use Bubba's Ignition 1330 Main St. Speedway In. 46224 1 888 809 3835 info@bubbashotrodshop.com They have good reviews and good info on their website
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TomO |
08-12-2014 @ 10:42 AM
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Posts: 7250
Joined: Oct 2009
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Grant, I don't know where you are located, but Yesteryear Ford Parts in Livonia, MI is a reliable source as well as Skip Haney in FL. I would look at the points in the spare distributor and see if they are just corroded from long time storage. I use a fine burnishing blade made by Jonard Industries. They are available at electronic supply stores. Here is a link to the website, where you can find a local distributor. http://www.jonard.com/jonard-ecommerce/control/product/~product_id=10043 I agree that the condenser or coil is the most likely suspects. Skip Haney has the best turnaround times for the coil rebuild. I hope to see you and your 36 at the meet.
Tom
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Grant |
08-12-2014 @ 5:11 PM
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Senior
Posts: 535
Joined: Oct 2009
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Thank you, Tom and Joe, for your recommendations. I did gently clean the contacts on the points and rotor in our spare distributor assembly before installation. They looked good. It hadn't occurred to me to ask Dave at Yesteryear if he could do a rebuild job. The last time I was at his shop, it was not far from Mason MI near Lansing.......about 185 miles west of here. It's an impressive place, and I have the impression that Dave can fix just about anything. A search in this area today...... southwestern Ontario ....... produced absolute zero. In terms of ready-to-go parts sitting on the shelf, no one seems to have what our car needs.
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supereal |
08-12-2014 @ 7:58 PM
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Senior
Posts: 6819
Joined: Oct 2009
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Just be sure that any shop you choose has a distributor machine such as a Sun or Heyer. I know Skip has one. Ours gets lots of use. Interesting is that these machines are now being built again, albeit at a price of about $5000! We bought two working Suns for less than a hundred bucks years ago. Any engine using non electronic ignition can benefit from their use in the hands of an experienced operator.
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TomO |
08-13-2014 @ 6:55 AM
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Senior
Posts: 7250
Joined: Oct 2009
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Grant, to determine whether it is the distributor or the coil/condenser, connect an ohmmeter or a powered test light between the coil contact on the distributor and ground. Wen you crank the engine over, the light or ohm meter will show when the points are open and closed. If you get a 0 ohms reading, the points are good. You can use the ohm meter to check for an open or shorted condenser, but the best test is replacing it with one from NAPA.
Tom
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