I have just installed my new rebuilt engine in the 27 Sport Touring can of worms project. I have it running and the engine sounds good . But I still have a very rough idle and it will sometimes "pop" back thru the carb when accelerating the throttle. I had rebuilt the carb last year and it seemed to run OK then. I had to tear it back apart as the threads had torn loose on the bowl drain valve threads in the carb body. I re cleaned the carb as the thread pieces had worked there way into the spray nozzle. The carb seems to be OK. The internal passages are clean, the spray nozzle is new and the needle is smooth. and the float needle seat does not leak. I have noticed that the points on the coils have a large spark. Is that a sign of bad capacitors.?? I also have changed to a NOS set of 1965 vintage coils that are untested. The miss is still there with the 65 vintage coils. They also have a big spark at the points. I have a New Day timer. It is used but good condition. All of this is on a brand new engine with about 1 hour of idle time. It is a professional built engine that I feel is very professional built and probably no chance of valve problems, ect. The intake and exhaust fit very well with new O-rings and glands. The side of the block was also machined. My Spark Plugs are champion X and are almost new (slightly used last year) Would the rough idle and "popping" be more than likely fuel or spark.....?? One other thing. It runs the same on battery or mag. really no difference.
A pure guess:
I think you should take a look at the timer. It could be that either something is wrong inside or the rod connecting it to the spark advance lever needs adjustment.
It sounds like timing, if the fuel mix is set right. But I would sure want to be sure those coils were tested and set correctly (i.e., not by buzz box).
The problem is the symptoms you describe are the same for fuel and ignition problems.
You have to eliminate one to fix the other and it can be totally exasperating.
Popping CAN be a problem of weak spark under the much more dense conditions inside the cylinders when more fuel is introduced but I'm thinking the carb float might be a bit low.
Donnie, Drain your fuel and put in some new gas with no ethanol. Look on :www. pure gas.com or get some aviation gas, it has no alcohol in it. or put a little product called Sea Foam additive and slosh the tank to mix. It seems that it fixes gas with alcohol. I have had a lot of problems on old engines with this new alcohol gas. Hope this helps, Kevin in Utah.
Sounds like you are running lean. Try opening the needle 1/4 turn at a time until it smooths out. If you were too retarded, it would tend to burn as the gas goes out the exhaust and heat up the exhaust manifold, but popping in the carb is usually caused by a lean mixture. Are you running a vaporizer? If so, maybe those familiar with that type carburetor can chime in.
#1 get those coils straightened out. Popping back through the carb could be timing but it would not cause a definite miss. A valve not seating could. Can you isolate the cyl. that's missing? Shorting out the plugs one at a time and looking for the one that has no effect on the engine will be the bad one. Actually that's your easiest/ first step. Checking for spark at the plugs.
I have good spark. With all 4 plugs removed I have a big fat spark at the plugs, you could weld with it. I will recheck the float level tomorrow. The miss is not a single cylinder miss. It is more of a very rough idle. It stumbles when giving it gas. And will pop thru the carb sometimes. I have shorted out each plug and all of them change the sound and running of the engine. Im going to order a set of coil man coils next week. I have started a rebuild of another NH carb just in case it is something has happened to the one on it now. Ill have to order some parts Monday. I have rebuilt at least 25 NH carbs with no problems they are useally a very simple rebuild. The only thing I did this last time I do not normally do is I replaced the float needle valve with a gross-jet as I did not have a good regular needle. Is it possible the gross-jet is not letting the gas thru fast enough .?? I think Ill find a useable old needle and seat to see if it will change anything. I also have a new Anderson timer I may put on. The new day timer on it now is properly timed as to crank position. It is set to fire the coils just after TDC with the spark rod all the way up. I have an old original NOS New Day I may try.. So far it sounds like a lean mixture may be the problem. I was leaning toward carb myself but wanted some more opinions. Thanks and will post what I find
Have you checked the sediment bowl screen for blockage ??
Donnie -- My advice: Toss the grose-jet and install the best used REAL needle and seat you have.
Bob, Everything is clean and new. I have a good fuel flow out the bottom drain on the carb. Mike I think Im going to try the old needle seat tomorrow. I have never used the grose-jets before, but I have about a dozen of them new in the packages. Since my repro needle seat had started leaking and that was all I had, I thought I would give it a try. May not be the problem, but it is something new. The bad thing about a complete overhaul and restoration is I have messed with everything.
Here are a couple pics of the carb I am currently cleaning up. They are of the cleaning of the internal passages. I believe that is something a lot of people overlook. I either melt out the old lead plugs or drill out the brass plugs. I then heat the carb body real hot to loosen any scale. Then I start with a 1/16 inch bit and using it by hand I clean out the passages. By using only your hands on the bit you will not mess up the carb body. Two of the passages are one size larger than 1/16 and one of the passages is two sizes larger. (I do not remember the sizes and its raining so Im not going out to the shop) After cleaning out the passages and finish cleaning of the carb body by glass beading, hand cleaning or ??? Then make sure the passages are clean with compressed air, and carb cleaner blown thru the passages. Then I cut a piece of 1/8 brazing rod to re-rivet/plug the holes.
Cut it a little longer than needed to reach the "seat" in the passage counterbore. Slowly drive it in place and start riveting it., when it is tight in the hole cut all the excess off except about 1/16 inch, then finish riveting it down to a nice shaped head. The one behind the carb gasket will need filed flush after riveting. Has always worked well for me. I have never seen a photo showing the drill bits in the passages. Thought maybe it would help some to understand the location of the passages.
"the points on the coils have a large spark"
That's usually the indication of a poor capacitor.
"The miss is not a single cylinder miss. It is more of a very rough idle."
Could be an indication of a worn camshaft, was the camshaft replaced on that engine?
Ken, Yes the cam is a new Stipe cam. Everything in the engine and trans is a good as can be done. New pistons, rings, bored .040, new cam and crank gears, new valves, adjustable lifters, block has been magnafluxed, head and block decked, side intake/exhaust ports also decked, EE crank cleaned up at .020. new babbit on mains rods, trans totally rebuilt and balanced with new 4th main, pan straightend on pan jig, built by a well known professional builder. I feel that there is nothing that can be mechanically wrong. Intake and exhaust manifolds fit perfect with new o-rings and glands. The gas tank has been totally cleaned and a new POR gas tank liner installed, The entire gas system is a clean as new. The gas is fresh. It is ethanol type but I have never had problems with it before. The timer rod is set with the crank position just after top dead center. The only two real unknowns are the 2 sets of coils I have are untested. and the carb may still have some hidden problem I am not finding. ?? I am going to replace the grose-jet today as it is something I am not familiar with. Even though I set the float height as it is supposed to be set, the grose-jet may not react the same to the float height.??
I replaced the grose-jet today. I had to use a used needle and seat. I glass beaded it and hand lapped it with valve grinding compound. I reset the float level to 1/4 inch like the service manual says to. Then I put it back on and the car, and it starts and runs good again. No popping at carb. It still is a very very very little bit rough ( yes 3 varys) for my likes, so a set of new coils is next. I am back to free starts, and one pull cranks on mag. My opinion on the problem is. When I rebuilt the carb last fall I installed a repro needle and seat, It sat all winter off the car and on its side. Something caused the repro needle to become a "leaker" ?? As a "leaker installed on the car it was running too rich and caused my first rough idle problem. Then when I opened it up to repair the "leaker" problem, is when I found the stripped thread tops on the drain valve threads, The pieces of threads had worked there way into the spray nozzle. During the cleanup of the carb and thread problem I had to replace the repro needle set with the new grose-jet, because its all I had at the time. Even though I set the float height at 1/4 inch like the regular Ford style needle set, It must not be right for a grose-jet. It must have been too low and caused a lean mixture. On a good Note, I idled the car almost a hour today before it started a little steam at the radiator overflow. I hope to test drive tomorrow ....... I am still going to rebuild the extra NH that I started on. Any suggestions as to the needle seats. What about the "Viton" tipped ones. Has there been any problems with the stock style needles. I have been away from model Ts for about 10 years. So a lot has changed since I was last working on them. Im having to re-learn some stuff.... Thanks for the help guys ....
Donnie, new needle and seats are available like the originals. I use them and really like them. Before switching over to these I had grosse ball type valves and had nothing but trouble with them. http://www.modeltford.com/item/6212OR.aspx
Stephen: That is like the repro one I bought last fall. I even got it from Langs. I just may have had bad luck with it. I have another one of that type in my order to Langs for tomorrow. The one I bought last fall looked very nice and looked like a high quality part, It may be that Murphys Law was at work.....
Two years ago at Petit Jean I put new hoses on my Hack the day before the show and forgot to put water in it before driving it to the Conference Center at Rockefeller farm for lunch. I was smelling something and realized it about the time I got there and let it cool as I eat. I filled it with water and it did fine on the way home. When I got back to SC, I unloaded and drove it around a little and noticed a skip. I was sure I had hurt something from running it so hot. My coils had been rebuilt less than a year prior. I shorted out each plug and each one affected it (like yours). I pulled and checked each plug for fire and they were good (like yours). I replaced my New Day timer with a new Anderson and reset the time,--no difference. Since I didn't have a new engine like you, I pulled the head and re-lapped and set all the valves and put a new set of rings in it with a new head gasket and still had the problem! I pulled all 4 coils and replaced them with a set I had just had Ron rebuild for another T. Problem was solved! The bad coil worked fine idling as I worked with it, but after driving it a while it didn't. Moral of the story--T's build character, and a rebuild of an 85 year old coil still won't make it last forever. Do the easy stuff first.
Donnie, good to hear that you got it fixed.
It's amazing how much rebuilt coils can affect the car, though. As long as they stay good.
Donnie, you say you're getting free starts? I thought free starts are the sign of an old, worn out engine, which yours sounds like anything but. I am impressed by the first pull mag crank starts. I'm not sure my mag is strong enough to do that.
Glad to hear you got it figured out. Happy motoring!
Jared: Free starts can happen on any engine with good compression. Not perfect compression just good compression is OK. They useally will not free start on a very tight engine. The engine may fire once and move the crank, but it is too tight to make it to the next cylinder, After a little break in time, and it loosens up some, they will free start. The main thing is having everything set right. I can usually hand crank on mag with one hard pull of the crank when the engine is cold. After it warms up, I can hand crank on mag with one finger (sometimes 2 fingers as this engine is still a little stiff). I have been away from Ts for about 10 years, so I am having to relearn some of my tricks. But if my engine did not free start at least 90% of the time and if I can not hand crank on mag with one pull and using one finger, I need to figure out why. You can ask some of the guys from Arkansas that remember me. They would look all over my car for the hot shot battery they thought I was using. It is true that a T can start on mag with one pull. A little trick I used to do was, Since my car would free start almost all the time, for up to an hour, if the temp was right. I had the spark control rod set to the point that if I pushed it all the way up, the timer would not make contact. I would push it all the way up and turn the key to Battery. Then I would take a lead weight I had made and hang it on the spark rod. It weighed enough to almost pull the rod down. It was like setting a mouse trap because it was all I could do to hang the weight, without pulling the rod down.. I had a small pillow on the floor for the weight to fall on when the weight would pull the rod down. So with everything set and the weight hanging, the trap was set. If anyone touched the car enough to shake it, the weight would pull the spark rod down a couple notches, and the timer would make contact and the free start would start the car. Usually scared the hell out of the "car shaker" If for some reason I wanted to show off I would drive up to a crowd, set the hand brake, kill the car, set the lead weight mouse trap, turn the key to Battery. Then when I was ready to leave I would walk over to the car and say "lets go home Lizzie" and kick the tire. The free start would start her up. I would get in a drive away. It was years before anyone caught me.... A very old man taught that trick to me....
That's pretty awesome. I'd love to have a car that well-tuned! Perhaps one day, after I build my engine...