| DVW | -- 06-26-2010 @ 6:18 AM |
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I completely rebuilt a 48 factory relieved engine in a 48 Ford convertible, bored out to .080, Isky cam #77,Johnson adjustable tappets, Offenhauser heads, Edelbrock intake with 3 97's. The front and the back are blanked off. I have changed over to 12 volt,I have a Mallory dist.I have a lot of Stromberg 97's and have tried several.The valves are straight. I used the original valve springs. When I first started this engine, It ran perfectly.It has gotten progressively worse.Popping out the tailpipe.Any suggestions?
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| 37RAGTOPMAN | -- 06-26-2010 @ 6:30 AM |
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when does it pop out the tailpipes ? going down a hill with the throttle off, or at idle? midrange? did you ad a TOP OIL ? valves sticking ? did you have the valve springs tested,and were determined that they had good tension,and were useable ? also check the intake gasket and the carb base gasket for air leaking in causing a lean mixture, also any EXHAUST LEAK will cause this when backing off the throttle., ignition wires are good? no cross firing ? let us know, 37 RAGTOPMAN KEEP ON TRUCKIN,,,,!!!!!
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| DVW | -- 06-26-2010 @ 7:02 AM |
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It pops some while idling, but if we rev it up , it pops continuously. I did not check the tension of the springs.New spark plug wires. adjusting the carbs seems to make no difference.I did not add a Top oil.It loads up with black smoke coming out the tailpipe.It has done the same no matter what carb is installed. This message was edited by DVW on 6-26-10 @ 7:06 AM
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| flathead4rd | -- 06-26-2010 @ 7:48 AM |
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You don't say if you have a fuel pressure regulator for your 97's. If you getting black smoke your carb is probably loading up. Strombergs need 2-1/2 lbs of pressure or less.
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| DVW | -- 06-26-2010 @ 8:13 AM |
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I am very slightly less than 2 lbs.
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| 37 Coupe | -- 06-26-2010 @ 10:01 AM |
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Before you worry to much or get to involved in tearing things apart or adjusting remove aircleaner and drizzle MMO ( Marvel Mystery Oil) down both sides of carb. This will get into both sides of valve chamber and loosen up what is probably a slightly stuck or sticking valve. The Ethanol gas is creating a lot of this remember they make corn syrup out of it too. If this is the problem it will cure quickly and then you can just add 4 ounces to every 10 gallon fuel in the tank to maintain free valves.This is not an old wives tale nor is MMO "snakeoil" it works.
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| supereal | -- 06-26-2010 @ 10:54 AM |
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With that cam, you need new valve springs to compensate for the "ramp" of the grind, certainly more than the 40 pound stock closed tension. We never reuse valve springs in any rebuild, as the tension decreases with age. Often, popping is due, or increased, by an initial advance setting that is too high. Aftermarket ignitions can exceed the usual 4-5 degrees. Setting timing on pre-'49 engines is hampered by the lack of a marked crank pulley, and is often "by guess". I have yet to see much discernible advantage produced by Mallory, or any other conversion, over the stock system in good condition on a flathead. I'm not among the MMO fans, as it doesn't take much to produce spark plug fouling. This message was edited by supereal on 6-26-10 @ 10:55 AM
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| DVW | -- 06-26-2010 @ 11:55 AM |
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This has become very frustrating. I am 74 years old and have forgotten what I once knew. I built this car the way I wanted it when I was 17 but could not afford it then. I want to thank all who have responded, I welcome all suggestions.
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| supereal | -- 06-26-2010 @ 1:49 PM |
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At 75, I'm in the same boat, and sometimes "popping out of MY pipe" too! I'm fortunate to have two mechanic sons at our shop who are patient with the "old man". Frustration is built into the old car hobby, I've found, at any age, and while my mental gears grind a whole lot slower, at least they are still grinding!
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| DVW | -- 06-27-2010 @ 5:10 AM |
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I checked with Mac's and Dennis Carpenter and all I find is stock valve springs, where do I get stronger ones?
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| 37RAGTOPMAN | -- 06-27-2010 @ 7:56 AM |
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FLATHEAD JACK sells a lot speed equipment and will tell you which ones will work the best, he sell his catalog for around $10.00 but worth the money for the info that is in there, hope this helps.37RAGTOPMAN KEEP ON TRUCKIN,
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| supereal | -- 06-27-2010 @ 10:10 AM |
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We buy our performance cam springs from suppliers such as Jeggs or Summit. Red's Headers would be another source. If you can't find them, the later 1BA type can be used, too. One other thought: before you tear into your engine, be sure that you don't have crossfire between plug wires, particularly if you have non metallic wires. One way to check is to wait until it is dark, start the engine and spray some water on the wires and watch for any arcing between the wires. Also, be sure to check the inside of the distributor cap for a carbon path. Either can produce exhaust popping. Since your problem took a while to show up, and has gotten worse, those are places to watch.
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| 40 Coupe | -- 06-28-2010 @ 4:53 AM |
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DVW: I would NOT take the engine apart until I explored both the carb and the distributor and do some more testing. Your running on the center Carb. I would get in touch with Max Musgrove in Utah and ask for his Carb. suggestions. Then have the distributor checked out including the coil output and condenser. Are you running a vacuum line to the distributor for advance? What plugs are you using? What is the vacuum level at idle? You may have a combination of a couple of issues leading to the problem.
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| JM | -- 06-29-2010 @ 5:48 AM |
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Patricks, Reds Headers, Speedway Motors, Flathead Jack, Dick Spadaro, maybe Joblot and others will have the heavier LZ valve springs. JM
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| shogun1940 | -- 06-29-2010 @ 9:06 AM |
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try a cylinder leak down test before you tear in to the springs then you will have an idea what cylinder was the3 culprit or take one plug off at a time to see if you caN ISOLATE THE BAD Cylinder, we used to do cylinder balance test with a tach and vacuum guage. the first 4 cyl. against the last 4 and then every other cyl. against the next set of every other set
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| gary duff | -- 06-29-2010 @ 10:58 AM |
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Sounds to me like you have some valve guide keepers between the top of the spring and the guide, instead of the groove in the guide. This causes the guide to pop up into the port and reduce the spring pressure. Gary
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| TomO | -- 06-29-2010 @ 6:17 PM |
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I would first try a stock distributor. The Mallory ones are not as good as the Ford dual point distributor.. My reason for suspecting the distributor is that the engine ran good and is deteriorating Tom
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