Before I get serious and start tearing things apart, I wanted to pass this by you guys. Rebuilt flathead has run perfectly for Three years now. Installed taller banjo gearing this spring. Other than that there have been Absolutely no electrical or mechanical changes made to anything on this setup. MSD ignition, Running the two outer bank Strombergs on this manifold. Using NGK B6L plugs. set at .025 all the way up to .040. Symptoms. The one plug fouls out within 10-15 miles after installing the new plug or cleaning the old plug. Plug seems more like dry carbon vs oily carbon. Most of the time, the miss is only evident during moderate acceleration. Not during high rpm acceleration. All the other 7 plugs are a perfect tan color. Maybe another clue??? The left bank ( the location of this fouling) slightly backfires through the exhaust during deceleration. The right bank rarely does this. The Number 5 cylinder is the only location of this fouling. What I've tried thus far. B6L plugs. set at .025 all the way up to .040. Replaced the spark plug wire from distributor to plug. Slightly leaned out the idle circuit only on the front carb. What I haven't done yet. Tested the new spark plug wire resistance. Advanced the timing Pull the cap and check for cracks or wear Tested for a vacuum leak. Performed a compression or leak down test. Am I missing something here?? If I find the cap is good , Could the MSD somehow be weak at one cylinder ? Frustrating. Especially since this engines been running perfectly since its installation.
Have you checked compression on the fouling hole? How are the valve clearances? I seriously doubt you would have an ignition problem on just one cylinder unless that terminal in the cap is somehow damaged. Sent from my iPhone using The H.A.M.B. mobile app
Things to try that are free or inexpensive before taking the engine apart. HRP Have you check your spark plug wire, It may have a problem, you could test it by switching out another wire, maybe try a hotter plug or you might try a non-fouler adapter, I used one on a old panhead and to my amazement it worked. HRP
Thanks for the advise you two. As stated. I haven’t begun any tear down yet. But did install a new plug wire. I first thought that was the problem but it wasn’t. I need to pull the (hard to reach) distributor cap first. I’m thinking it may be the problem. Yes I am first doing the easy stuff. Hell of a time to tear into an engine at driving season. Danny. Never heard of a non fouler adapter. I’ll have to look into that. More info. I installed a new plug and dropped the gap from 025 to .015/020 and noticed a 50% improvement. It ran perfect for 15 miles at high rpm on open road then began a slight miss at low rpm. But bringing it back to a high rpm @ 60 mph cleared the carbon and it ran well again. An occasional miss at low rpm continued for the next 30 miles but at high speed no miss. Not even a flutter.
You cannot make something from nothing. That carbon came from someplace? The other cyls are not having problems. So its gotta be the piston and or rings on the offending cyl. maybe a gummed up stuck ring. Fill the cyl with a mix of acetone and diesel. or MM oil . and let it soak a couple of days. then turn it until both valves are closed. mahe a fitting from old spark plug to apply air pressure to the cyl. hook it up and put as much air pressure as you can into the cyl. that will force the mix past the rings and might blow any crud out. change the oil and drive it. If it continues you gotta tear it down. I doubt its the valve guides.
I agree Old Wolf. Yes if my cap is good I do have a cylinder issue. Carbon is from unburned gas and I need to find the cause. I’ll definitely try the fix you suggested once I’m positive it’s not an electrical resistance issue. Thanks so much for tip. I’ll let everyone know what I find as soon as I get there.
those are non foulers they lower the compression about a CC worth. they remove the plug from the combustion chanber. They are mainly for engines that are burning oil.
Thinking back . I remember about 50 years ago I bought a black 61 ford more door 352 auto . It had a miss. never smoked spit out the carb sometimes. I paid $50 for it and everyone had worked on it.it had new cap rotor points condenser coil wires spark plugs . rebuilt carb and valve job. I was setting the points with a dwell meter and it had a steady jump. one lobe on the dist was worn down. changed the dist and it ran perfect. I took the dist apart . I finally decided some one had at some time filed the points with a aggressive file and damaged the hard outer part of the lobe and it wore down over time.
That adapter just may allow me to run the engine and get whatever crap is causing it to loosen up. With the adapter I may be able to get it out and run it at 65 mph for an hour or so and see what happens. I've been guilty of babying it. By the way, no oil consumption on the engine. its a dry carbon and the anti fouler may not even work. Am running the hottest plug available.
Check the valve clearance and do a compression check, as suggested, first. The problem is likely a lack of compression in that hole. The clearance adjustment may fix it. If not, you will have to at least pull the head.
Realized the NGK plug numbers are hotter with the lower number. I Installed a hotter plug along with a non fouler and ran the truck all weekend without a miss. Going to drive it more yet before pulling the plug and distributor cap to inspect. With no fouling issues under these conditions, this points to a cylinder issue. Otherwise electronically it would still show a miss. I hopefully am going to get through driving season this way and tear it down this winter.
Sad news indeed today. Pulled the head of the offending plug fouling cylinder and this is what I found.
It appears I have a rust issue entering the cylinder from a nearby water jacket. . Plans are to check all the other walls and either replace the engine or sleeve it. What a bummer. This engine was rebuilt a good while ago with few miles. Ran perfectly. Frustrating.
Like the roll of the dice. You could easily bore out a cylinder, inspect and find a clean surface not knowing water/rust corrosion could easily be only a few thousands away from the machined surface. There’s no indicator other than maybe X-ray to see this coming. Bad luck on this one. I’m bummed.
Have you ever had any issues with losing antifreeze since it has been together? That etching pattern looks like it has had a puddle of water sit there for a while and pit the wall. It looks kind of crescent shaped . And then it has a slight one again above it to the left. If it had a gasket seeping water into the cylinder and sat for a while,,that would cause something similar to that pattern. Either way,,,looks like it will need a sleeve at least . Sorry. Tommy
UGH! That sucks. I've noticed that this hobby is full of that kind of shit. Kind of like owning a boat $$$$. Upside, at least when you are done fixing it you'll have a good motor you can trust.
If you can’t take the heat... stay oughta the kitchen. I’m leaning towards beefing up another flathead instead of taking chances with this block. You know, I never had any issues with losing any coolant in this engine. Yes I’ve noticed the half moon shapes to the corrosion.
I’m with you Pete,,,,we’re gonna spend our money on something. It might as well be a nice Hot Rod ! Tommy
Petejoe, I'm in the exact same boat, I've assumed ownership of a car & drivetrain exactly like yours. My bro bought my car (Fiddy Ford coupe) 30+(3500ish miles) years ago & the drivetrain was supposedly rebuilt at that time. I've replaced everything(rubber) that seems to be leaking, but have put zero miles on it. I've had it running long enough to know the water pumps were bitched, but it ran good after filing the points, so I'm gonna roll the dice. Luckily I have another ride (O/T) & CAA and will take what I get (will be my daily back & forth to work, til it proves itself). Hope to make it my highway car cuz it's got overdrive (unproven). It's got curb appeal!!
Found a nice replacement. A 59L to boot. Cant wait to fire up this monster...….. Factory Relieved engine. With some more removed. Offenhauser pistons and rings. Clay Smith camshaft. 282 duration. .325" lift. Ford exhaust valves. Oversize intake valves. Zephyr valve springs. Iskenderian lifters. Melling high volume oil pump. Selling my Truck engine cheap. Will need sleeved but a good rebuild candidate. 1940 59A also an 1951 8BA. I removed it from a low mileage original car. Has set in my heated garage for 7-8 years. I rotate and spray the cylinders on this every year. make some offers......
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