| Maine | -- 10-20-2019 @ 11:31 AM |
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33/34 Ford Engine ran fine after recent machine shop complete rebuild. Trial runs totaled 20 mile showed high water temperature and so, the radiator was sent out for cleaning and review. The trials continued for around 30 miles with success with the temp around 150 degrees. After sitting for about a month I started the engine and it seemed to run rough and lacked power and backfired out the exhaust on deceleration . During the rebuild, I replaced the rotor, inner& outer caps plus the wires and one dist. bushing which had some play, reviewed the coil contact points and setting and lubed all that is asked for. The spark plugs were manually cleaned and reset as they appeared relatively new. I bought the car summer of 2018 it seemed to run fine but found compression low in one cylinder so the engine was removed to rebuild. In regard to the fuel system, The tank was new, but I replaced the fuel line, installed an inline electric pump, new diaphragm in the mechanical pump and checked the float level. My last activity to fix the rough running and backfiring exhaust was to clean the spark plugs 7 out of the 8 were very black and replace the condenser with no luck to fixing the problem. With the engine running, removing the secondary wire at each plug, the spark will jump a quarter of an inch on each plug white/blue spark. Any suggestions:
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| supereal | -- 10-20-2019 @ 11:50 AM |
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Looks like an out-of-time problem. Best guess is that the timing gear has jumped a tooth or two. The fiber cam gears tend to get fragile from years of service, and tooth failure isn't rare. Check with the shop that did the rebuild to see if the timing gear was replaced. It is also possible that the crankshaft gear has sheared it's key.
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| 40 Coupe | -- 10-21-2019 @ 3:45 AM |
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So it ran OK and then it sat for a while, after sitting it then ran poor. It is very possible you have a valve sticking . You may want to try MMO to free the valve. It appears the Carb. is running rich, what Carb. do you have and was it rebuilt? Try a compression test it may tell you what cylinders have the sticking valves. You might consider thermostats to get running engine temperature up since 150 is low. Did you retorque the heads, at least once, after your trial runs? Check the fuel pressure at the Carb. If you have a Stromberg Model 40 make sure not to exceed 2 1/2#
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| Maine | -- 10-21-2019 @ 6:46 AM |
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The timing gear was replaced during the rebuild. Although I didn't do a compress test when I first installed the engine I did one during my diagnostic tests and they all registered between 70-75# which I thought was low even on a somewhat cold engine. The carb is a Stromberg don't know the model but do think it is and was running rich even before the problem. The float was checked and is at 3/16". Pictures in parts catalog looks like it is a model 48. Don't know the fuel pressure at this time and if it is high how do I tame it? the electric pump is the carter brand 2-4# pressure.
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| Maine | -- 10-21-2019 @ 6:52 AM |
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The heads were retorqued after the first running of the engine.
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| 40cpe | -- 10-21-2019 @ 8:34 AM |
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Maybe stuck valve/valves after being not used for a while? Run Sea Foam or Marvel Mystery Oil through the carburetor as per directions.
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| rustedorrotting | -- 10-21-2019 @ 8:37 AM |
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just ran into similar problems on my 41. the power valve was leaking and filling my crank case with gasoline which resulted in a rod knock. check your oil level. there is a place called Charlies speed shop in Florida that sells an inline pressure gauge and pressure regulator. Some folks here don't care for him, but he has been very helpful to me.
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| Maine | -- 10-21-2019 @ 11:57 AM |
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Talked with Jeff at the shop that rebuilt the engine. He can't come up with why the timing gears would fail so early, fiber gear is new and all press fitted tight. after further discussion on my activity he determined I should address the rich fuel problem. This was based on my the running of the engine right after recleaning the spark plugs. The engine ran fine for about 15 minutes smooth and the turned rough again and started to backfire at the exhaust when dropping back to an idle. I can't smell gas in the oil but it does blow black smoke when it runs rough. The carb is a Stromberg 97, and at this time, I don't know the jet size nor do I really know the vintage of the engine. the heads are 19 bolt cast iron. i
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| MG | -- 10-21-2019 @ 12:28 PM |
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Is the mechanical fuel pump new? Some of the new fuel pumps (off shore) out there have excessive pressure. There's been a rash of reports of the symptoms you are experiencing caused by excessive fuel pump pressure. Ideally you want 2-1/2 lbs. pressure - no more....
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| 37RAGTOPMAN | -- 10-21-2019 @ 3:09 PM |
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HI Maine did you try using MARVEL MYSTERY oil in the fuel, I think you have sticking valves, especially the exhaust valves this happens when the engine is not broken in and sits idle for a period of time, worth a try ,,,,, also with the engine running, use a light and a mirror and look down the carburetor and check to see what is happening, is gas flowing over ?maybe a bad float or needle valve, causing overflow down the throat of the carb ? causing running rich hope this helps 37RAGTOPMAN MAINE This message was edited by 37RAGTOPMAN on 10-22-19 @ 10:23 AM
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| 40 Coupe | -- 10-22-2019 @ 5:43 AM |
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The typical float setting for a Stromberg is 11/32" down on the free end from the top of the bowl. The standard factory jets are: Model 40 or 48= 0.048" Mains and #63 power valve Model 97=0.045" Mains and #65 power valve. They should all be marked. The original Carb for the 34 was the Stromberg Model 40 which is nearly identical to the Model 48 used in 1935. By 36 Ford changed to the Model 97 for better fuel economy. Ford Strombergs used an all metal input valve needle some aftermarket needles have a Vitron tip which is not stable with alcohol fuel. Not a good idea to run more that 2-1/2# of fuel pressure it can cause input valve to leak and excessive fuel in the float bowl. If your above this level I suggest removing the electric pump and have your original pump rebuilt by Charlie Schwindler. Excessive fuel tends to wash oil film from valve stems and rings
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| Maine | -- 11-03-2019 @ 2:54 PM |
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At this time I believe I solved the problem by addressing the rich gas problem, rough running and backfiring at the exhaust. the combination of going through the carburetor, running Marvel Mystery oil in the fuel supply and then running the car on the open road at 50 mph and a total 15 miles. On the existing 97 Stromberg carburetor I installed new jets .044, emulsion tubes, a designated 97 model power jet, idle jets and idle screws, and the new Grose jet that allows higher inlet pressure. The accelerator pump looked new but I did replace the pump check valve. The existing main jets were marked .045 but one had orifice almost twice the size as the other. I also decided to install a new diaphragm in the pump as I had it on hand. So the 97 Carburetor is from a 1936, is there some way to identify the year of the engine? With winter weather on the horizon, I put the car away until spring. I learned a lot through this problem and appreciated all the suggestion I received. Next spring after some more road trips I'll check the spark plugs to see if the fuel mixture is ok. Thanks to all of you who gave me so much info.
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| flathead4rd | -- 11-04-2019 @ 8:22 AM |
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Sounds like you have solved your problem. I just thought I would add my own experience with the same exact problem for future reference. After checking all the possible problems I could think of including resetting the adjustable lifter clearances and still having the backfire out of the tail pipe, I decided the only place left to look was at the plug wires. Sure enough, #1 plug wire was breaking down and causing a weak spark. It would fire just enough to almost go unnoticed. Replaced it and problem solved. A lot of hours spent on such a simple solution.
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| Maine | -- 11-05-2019 @ 2:32 PM |
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During the time the engine was being rebuilt I went through the distributer . replaced the rotor (key was worn resulted in some drive play), one bushing on driveshaft had play so it was replaced, reset points (looked good ) replaced inner and outer caps and the spark plug wires. When the problem developed I checked the spark at each plug and it appeared ok but I did have a new condenser so I replaced it and still had the problem. At one of the members suggestion, I checked the voltage at the coil and it was low at 2.4 volts, so since I had a new resister I replaced it and got 3.3 volts but no change in problem. Just so nice having a great teem from the members working with you to solve a problem. Thanks for your input.
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| 40 Coupe | -- 11-06-2019 @ 4:23 AM |
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The 33-34 engine block does not have a breather passage on the front of the engine block. The breather came into use after 34. Look at the bottom of the engine at the front, RH side of the oil pan and see if the small triangle shaped breather is there or if the block above this area has the breather passage.
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| sarahcecelia | -- 11-06-2019 @ 9:04 AM |
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Back firing out the exhaust can be retarded timing. We used to do that as kids to make them backfire like that! Regards, Steve Lee
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| supereal | -- 11-14-2019 @ 12:16 PM |
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Check the engine with a vacuum gauge. One possibility is that you have an exhaust restriction. This allows an engine to start and idle, then the vacuum drops as the car is run. It can be from a carbon filled muffler. If you tap the muffler with a hammer, and you get a dull thud, it is time to replace the muffler. I have seen them so filled that they were hard to lift! If you don't have a vacuum diagnosis chart, I can post one or email it if you leave a message in my box on the header of this site. The vacuum gauge is still a very valuable diagnosis tool, and we use it often at our shop.
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