Ford Flathead 6 (226) problems..need help

I recently bought a 49 Shoebox Ford with a Flathead 6 (226). After years of sitting I recently was able to get it running (with help from the shoeboxford forum guys). I never got to road test it because it wasn’t legal (plates, ect). It idled and revved fine but it had a slight tapping noise. I’ve read on many threads how great Marvel Mystery Oil is for things like that. I poured some in the gas and engine oil as directed. I poured some down the carb while the engine was running, it smoked like everyone said it would. Then it started running rough and backfired through the carb. Now it starts and idles rough, if I give it any throttle it dies immediately. So far I’ve
Disconnected the fuel line to the carb and cranked the engine – its getting fuel
Tore apart the recently re-built carb (1bbl ford 8ha) to check for blockages and replaced the power jet assembly and fuel mixture needle
Replaced the points, condenser, cap, rotor, and plugs – firing order is good
Performed a compression test – all cylinders between 95-100
Re-set timing with vacume disconnected
Ran engine with vacume disconnected at distributor – no change
Checked for vacume leaks by spraying carb fluid around the based of the carb and vacume hoses – none found
Tailpipe is clear of obstructions
After all this I got another backfire.....I’m out of ideas please help!!!

You said that you put MMO in the fuel. Did you drain the tank and refill with fresh gasoline?

My tank was being re-sealed. I'm using a 1 gal gas can to run the engine while I work on it. Added very little MMO to the gas.

I performed a vacume test today. The needle rapidly swings back and forth from 10 in to 20 in. This indicates a valve issue, but the compression is good. I'm thinking a broken valve spring. Any thoughts?

Could be a chunk of crud loosened by running after years of inaction, loosened by the MMO, or something dropped down the carb getting between a valve and seat. If it is not too big, it might not show up on a compression test especially if being cranked fast by 12 volts. Try starting the engine and then disconnect and ground one spark plug wire at a time. After each disconnection, try accelerating the motor. You will get a pop back from the bad valve cylinder only. The plug in the bad cylinder is firing the mixture and it is burning past the intake valve and back into the intake manifold. When it burns all the fuel in the manifold the engine dies. At higher rpm under no load it would probably not do this but with a load it would.
If there is something between the valve and seat, that valve will tick or clack. If you can get it to run fast on 5 cylinders, the valve may clear itself. Or it could be something harder than a piece of carbon and do more damage to the engine. Good luck, you can at least isolate the offending cylinder. Richard

I'm thinking the same line about something dislodged and caught holding a valve open. If you have had it running this valve being open with fire all around it will be extremely hot and upon shutdown could warp very easily and may not seal again. Good luck with it.

Fred

I can't even get the engine to idle now. It starts and dies before I can get to the carb. Getting ready to pull the head. Once the head is off will it hurt it to crank the engine with the starter to watch the valves or should I crank it by hand?

Won't hurt anything to hit the starter to whirr it over to watch the valve action.

Fred

You got a carb problem. get rid of that carb and go with a Holley 347 single barrell. You can get them from www.vintagespeed.com If you got even compression at all cylinders then there is no way that a valve is stuck open or that there is an obstruction between the valve seat and the valve itself. On the other hand Ive seen brand new distributor caps come through with hairline cracks between the contacts, and also new rotors with the contact slightly loose. backtrack and take your time. Vinny G.

Vinny,
I've got another re-built carb that I was saving for 2x1. I'll swap them and see if that makes any difference. As for the distributor cap, there was no performance difference between the old one an new one, however, I'm not totally convinced that its not a distributor problem. As for the compression test, I agree that a valve is not stuck open, but I'm thinking a weak of broken spring. The vacume gauge was all over the place. It was swinging from 10 to 20 inches. I'll start with the easy stuff first and hopefully I'll get a Christmas miracle.

Several times I have had trouble with the wire in the distributor that connects the points to the outside of the distributor. The insulation being up to 60 years old it detiriorates and can cause an intermittant short causing the engine to hit and miss. Also had trouble with water condensing in the cap and on the rotor or on the coil tower in damp weather. A bad condenser can cause a backfire at times. If you think you have a carb problem and the engine does not chug black smoke (rich) you can check for a lean condition with an oil can by squirting a little gasoline in the carb while the engine is running. The first thing to check is that you have a good spark while cranking. Many old Ford solenoids have a button on the bottom for manually cranking the motor. If not, shorting from the battery side of the solenoid to the start terminal of the solenoid will crank the engine. These old Fords were Positive ground unlike modern practice. They will run with Negative ground but the spark will be weak unless the terminal wires on the coil are reversed. On 12 volts, without a resister, the 12 volts will burn the points in short order. Good Luck and let us know what you find.

I tried a second carb that I also rebuilt and it performed the same way. I pulled the points wire and it looks good, will replace it tomorrow. Cap and guts looked dry despite 1.5 inches of rain today. What bothers me is that the engine acts like it is starved for fuel. It will stay running if I spray starter fluid in it. I disconnected the fuel pump and cranked the engine, a steady stream of fuel came out. Maybe I'm doing something wrong in the carb reassembly. The bottom of the float measure 3/16 inch the jet is a 65. Other than the mixture an idle screws, I can't think of anything that can be wrong. The point gap is set to .025 Any thoughts before I start taking off the manifolds????

Ok, have you inspected the top of your coil tower for cracks or the wire shorting out to the clamp?

Coil and wires are less than a month old and just have some idle time on them. They were on there when the engine ran good. I'll give them a good once over tomorrow.

I think the point gap is supposed to be .016-.018

Have you inspected the in line neoprene fuel line at the back of the engine block/firewall? When this neoprene line becomes badly worn out over time it has a tendency to internally collapse under pressure.........Vinny

Fred,
I went with the point gap listed for Part#7ha-12127. I need to verify which distributor I have. That could be it. I changed the primary and ground wires under the breaker plate today and now I'm not getting any spark. Talk about going backwards, I think the primary wire might be grounding out somehow. Anyways, I'll check the part # tomorrow.

Vinny, I guess I don't know which line your talking about. The only flex fuel line I have is going from my fuel pump to my gas can.

It appears that only one of the 2 distributors fits a six cylinder. My book shows a point gap of .024-.026. The v-8 distributor has a point gap of .014-.016

Problem soved! I took my first test drive today after 3 months of hard work. Thanks for the advice. It turned out to be teflon tape clogging the fuel pump output line. One of the first things I checked was that line, but I missed it. The distributor I rebuilt works great. After setting the timing and getting the carb tuned I hooked up the vacume gauge again. It went from a rapid 10 psi swing to a rapid 3 psi swing. Guess the valves are sticking some, but once I can drive it some, maybe they will free up. Thanks again for all the advice. - Dustin