Flathead running rough

I´m new with flatheads and not too much an engine guy. I´ve been playing with four cylinder cars for 20 years, but I´m by no means an expert on engines. Flathead engines are totally new for me.

I have a 48 Mercury flathead with Strömberg type carburator with electric fuel pump and pressure regulator. I have not checked what is the current fuel pressure.
Engine has Mallory two point distributor and cables and spark plugs are quite new. I checked plugs and they were dry, maybe a bit more snotty than normally.

Engine is running rough and uneven, I found it impossible to drive it on idle or low rpm. I plan to disassemble the carburator next, I already checked the points, changed coil and condenser(to another used ones). I plan to buy new condenser, I suppose flathead uses an universal kind of condenser?
Can you help me? I suppose there is some "do this and that" tips for flathead?

 

Check your ignition leads make sure they are in correct order not crossed, if you have a timing light connected it to every lead one at a time if it is not flashing on certain leads you know that cylinder is not firing.

 

Thanks, I´ll use this as reference.
http://www.thehotrodcompany.com/blog/post/1946-1948-Ford-Flathead-Spark-Plug-Wiring.aspx

I have a timing light, I need to try that also, even thought the plugs looked fine out.

 

I don´t have this "front" distributor in my engine, but the "diagonal" later one.
It looks like later distributor has clockwise rotation. I suppose mine does also then?
http://www.vanpeltsales.com/FH_web/FH_images/FH_engine-pics/Flathead_Sparkplugwiring-49-53.GIF

 

Was this engine running correctly before or have you just acquired it? Don't go to the carb until you check the fuel pressure. Absolutely no more thank 2-1/2 pounds pressure. Also cheap electric fuel pumps are known to change pressure. Be sure the pressure is constant. You may just have dirt in your tank... lots of possibilities.

 

I have some dirt in tank, it´s a model A.
I have a original sediment bowl + new filter before pump. New (used) pump is Mitsubishi, not the cheapest one. I need to check the pressure, I have pressure regulator, but it does not have a "display". Previous pump did hardly fill the regulator, but this new one fills it alright.

I bought the engine from my friend and as far as I remember it worked fine in his car.

 

Has the engine sat not running for a while ? Could have a valve or two hanging open,might check compression

 

Put the filter in after the pump. Most electric fuel pumps are "pushers". For the most part, they rely on gravity to get fuel to the inlet. Not saying thats your problem, but at least fix that part.

 

I have now original cowl tank with sediment bowl -> hose to under the passenger floor where is filter + fuel pump -> hose to regulator with filter in cowl on the carburator level.
I have two filters, one before, one after the pump.

Engine was sitting 2-3 years, I need to check the compression. When I was finishing the engine for paint, it fell once over. Not high, but from a trolley. No outer damage, hopefully I find no inner damage either.

 

You say you checked the points and condensor. Was the check a visual? Check you coil and condensor with a digital multimeter. Thats the only way to tell if its working correctly or not. Also if you have a dwell meter you can check the points.
Use a vacuum guage (is there a port on the manifold?)to see where the vacuum is...that will tell you alot right there. Swapping parts will just waste money. All the info should be on the Vanpeltssales site.

 

If you have any trash in the fuel tank, it will keep plugging the filter. Also most fuel pressure regulators have a port for a small gauge......you really need to know what is going on there. Also agree about the possible sticking valves. good luck

 

Condensers do not store well. Old Mallory ones were good but new ones not so much. I would find new ones and get more than one to get at least one good part. In Finland, it may not be so easy to find.

You may have a blockage or maybe a small fuel leak in the carburetor. Clean it out & blow passages clean for overhaul with a kit. Check for warped surfaces between base & body.

 

Just read an article in the July issue 2013 of "Hemmings Classic Car", Tech talk section. The gentleman, Dave Berkemann, responded by stating the fuel pump pushrod was the issue in his car. This happened 50 years ago. His mechanic told him to "take off the fuel pump and pull out the push rod. The mechanic then, " applied a small drop of silver solder to the bottom end, ground it flat" . "Solved the idle problem anlong with vapor locking in the heat."

 

I have a model A using the model A tank. It has a filter that goes up into the tank and screens out large pieces of dirt and it can get plugged.

 

I recommend to you, and anyone that has a flathead Ford, to join the sister forum to this one, the FordBarn. There are many flathead experts here, and there are many over at FordBarn. You will get the best knowledge available by being on both sites. Works for me.

 

Ditto, re; fuel pressure. if you don't have one, be sure to add a pressure regulator, and check it's setting, to no more than 3 PSI.

4TTRUK

 

I disassebled my carb, Holley 94, and changed injectors or how so you call them. Now there is no idle, I need to change the old ones back. I saw the new ones had one hole less, they were for strömberg 97. I have now fuel pressure meter but could not yet try it.
I am kind of slow with this, because my garage is in other town.
I am at fordbarn but hardly never use it, maybe I should.
Thanks all for your advices, I 'll try to figure out the issue more in the weekend.

 

I bought that small filter, but did not change It yet. I should try to rinse the tank at the same time.

 

You sir are chasing ghosts. Please check for correct constant fuel pressure before making any changes to your carb.

 

I will, carb was clean and recently rebuild.

 

Ilari,
It is just an internal combustion engine. being a flat head does not make it majic. it has the same requirements as any other engine to run properly.

If you have a regulator and have no idea what the fuel pressure is then you may as well not have one, put a T in the line right after the regulator and see ahat pressure you are running.

next and always the first thing you do when one is not running prpoerly is to go step by step through a tune up. make sure that everything is set properly and that nothing inyour normal tuneup is stopping it from running right.

Now everything is correct you can start eliminating problems with it.

 

I´ve been working with the flathead and had no turning point. I have eliminated the carburator problem and yesterday checked the spark with two different timing lights. Spark seems to be irregular, somehow it´s missing spark time to time.

I have changed condenser, but the points are still the old ones. They seem to be good, but I ordered new ones already. Cables are silicone and spark plugs are original type and they look fine out. I took the coil out of Volvo, but I suppose there is no difference in 8 cylinder and 4 cylinder coils?
Mallory distributor is quite new and has no play.

I´m planning to borrow original type of distributor from a friend and see if it corrects the problem.

 

Have you checked the compression yet?The valves like to stick after the motor has been setting & you might have to take the heads off & put some lube on the stems & tap them down,roll the motor over & tap it down until it frees up.

 

Did you ever change your spark-plugs?
Had similar problems with my french-flathead. It turned out, that the 23 year old swiss spark plugs had been the problem.

 

A voltage drop test across the points with key on and points closed is a good way to judge points condition. Something like 0.3 volts (DC) max I seem to recall.

 

Spark plugs were quite new when I bought the engine, but I have NOS set of champion plugs waiting. I need to change one which seems not to get even spark and that will tell a lot.

 

I have not checked valves, but I tested compression with compression meter. Or what ever you call it. It showed good results to all chambers. I have not taken the heads off yet. I was planning to change heads next winter.

 

I need to try this if the problem continues.

Summer is too short in Finland, so I decided to buy me a electronic ignition. I bought one of those Hunt Mag-look distributors. I googled a bit and seems to be that there is good and bad experience on them. If someone has one of them, any tips are welcome to avoid the bad experience.

 

Unbelievable difference, I changed all spark plugs with uneven spark(6). Now it sounds as it should with hot cam. Still has some noise coming out, hope it's not a valve. Anyway, I'm planning to drive this thing tomorrow.