Going to bring this up only because it hasn’t been addressed yet. Even one backfire through your carbs will blow out the power valves. Yes even one.....
I had a similar problem with my flat head checked replaced ignition parts, pulled cover. Drove me nuts. Primed a carb to try to get it started. Ban it started. Have stromgergs on it. The rubber tip needle seats were sticking in seat. Not giving the proper fuel. Replaced with old style needles Just a thought. Drove me nuts. Ran like it was out of time.
The first thing I would check is spark. Take off the cap, rotate the engine until the points are closed. Turn the key to "on", then using a screwdriver or pick, without grounding anything pull the points open, if the ignition is working you should hear a spark snap in the cap. The next thing I would check is the plugs; are they wet with fuel, or dry as a bone? Does the engine try to start if you prime it? The next thing I would do is drain all the fuel out of the vehicle and check it for water. Water in the fuel is why I try to get my gas at the same station.
Couple things to check- 1) coil resistance : you need at least 3 ohms total, so if you have a 1.5ohm coil, you want a a 1.5 ohm ballast as well. If you have a 3.0 ohm coil, then no ballast. 2). A lot of new condensers are junk right out of the box- there are a couple guys that are selling really nice ballast resistors (search under Bubba for more info) 3) your compression check seems like the cam has not gone flat but perhaps you have a valve sticking once in a while? 4) if your tank was not new you may have some crap blocking the suction or your filter is blocked up. keep us posted!
I don't do flatheads so I am not up to speed on their distributors but I chased a no start issue in a SBC and eventually found that the rotor button had shorted through the plastic grounding the spark by way of the distributor shaft.
I'd seriously consider getting a stock single carb setup on it for trouble shooting if you are having this much trouble. (I love flatheads because you can change the intake without draining the cooling system.)
It's definitely not a fuel problem. I get a nice spray and the plugs are damp with fuel.. It also acts like it wants to start so I know it has fuel and spark but not at the right time. It doesn't backfire through the carb, just kind of coughs and spits up fuel. I no longer have points in it. I have an ignitor II with a 3ohm flame thrower coil so I can take the points and condenser out of the equation. I guess my next step is pull the timing cover off and see what I find.. Sent from my SM-G973U using The H.A.M.B. mobile app
My 59ab just stopped starting out of the blue. After weeks of fiddle farting around... reset points, changed condenser and coil, etc.....still no start. Still almost no spark at plug #5....#6 same as #5, # 7....disconnected and car fired right up. Hairline crack in distributor between #7 and coil.....everything grounding out thru #7. New cap and good to go. Go figure....Good luck....its something simple.
I RAN A EARLY MALLERY AND HAD SOME PROBLEMS WITH THE CONDENSER. It's one of those big copper ones- hard to find. Just as a test try a standard condenser. They don't like extra heat( sitting after a long run, might have shorted it internally, good luck.
One thing I never tried on a FH, but can you pull #1 plug and get something through the hole to the top of the piston? If so you can get a pretty good idea when the piston is at TDC, then see where the rotor is pointing. In fact it would probably be easier to pull the head than take the front of the engine apart
Just mark your crank pully for #1 TDC and just a timing light while cranking to see it the ignition is in time.
Is that fuel any good? Sounds to me like the fuel either has water in it or it’s not very combustible. See if it will run on gum cutter. Sent from my iPhone using H.A.M.B.
If I read this correctly, It hasn't ran since the pertronics was installed. I would look there. I'm no expert but believe they need full voltage to fire. It did run with the points, I would try some new points and go from there. Good Luck
Sounds to me like an intermittent short in the wiring to the ignition. It could also be an intermittent open circuit. When it reconnects while running it would cause a backfire through either the exhaust, the carb or both depending on what valve is open when it shouldn't be ready to fire. First thing I would check is the ignition switch. If that's good, start checking the wiring for breaks or shorts (bad insulation). Breaks in the wires can be hard to detect. A test light, an ohm meter and a helper are the best way and a lot of jiggling. Pull a jet plug out of a carb and check for water. I really don't believe you have any problem with the engine itself.
@fastmike before you dig into the front end check the genni and like @Glenn Thoreson said the ignition switch can be the issue. The aftermarket ones short out and believe your fighting a short and high amp draw and robbing the spark. Good compression wet plugs good fuel well at least to start or fart good spark if so did you pull or use plug out sitting on the head whats the spark color ?
I just noticed you said pertronix..... I had a similar issue when trying to start mine. It was complicated by having an msd in the mix that ended up being fried but I learned a couple things along the way- 1). The 7mm solid core wires can mess with the pertronix, and I changed to 8mm resistance core. I just drilled my Mallory flat cap a touch oversized to allow them to fit. 2). On google there are a couple good videos on testing your pertronix with a test light to see if it triggering properly (they are easy to fry- especially if you leave the ignition powered up for extended periods of time without the engine running) 3). Even though you are not supposed to have to change timing when installing pertronix- I had the dizzy timed properly with points and running well, then when I installed pertronix, I had to rotate the dizzy clockwise about 15 degrees to get the same timing with pertronix (see photo 2 Sharpy marks on block)
Maybe an obvious one too- but you might also want to loosen the 2 screws holding the cover to the cap and make sure you have the wires pressed on to the the little nibs well and re-tighten the cap. And also check that they are centered on the nibs well too.
I'm thinking the pertronix may be the issue. Do you have another distributor you can swap in to try? Or swap the points back in?
The easiest way to check if the ignition is working is to pull a plug wire at the plug, plug in a spare spark plug into the plug wire, ground the shell of the plug (the threaded part) against the engine block or cylinder head, then have someone crank the engine while you watch for a spark. Let us know what you find.
I'd try putting a stock dizzy in it, just to see if it would start & run. That would at least clear or elimnate the Mallory. I had a Y C in a flathead once & took it out as it was problematic. Too many moons ago to remember what the problem was.
If your looking to collect some data you may want to hook up a vacuum gage and set the timing to get the motor to produce the most vacuum then compare that to what you have it timed at. I would also swap the pertronix out for a stock one to see if it cures the problem. Good luck on your quest
In the first couple posts that @fastmike stated he rebuilt the original dizzy with new points and cond. sounds like no good results so a pertronix went in and problem still exists. I know swapping parts out doesn’t yield the best results and could exacerbate the issue. Some great ideas and I am sure this will be a silly fix when found...
Sorry if this sounds silly but I'm too old school and not familiar with these electronic ignition things. I have read posts that states one brand of these things is not reliable and folks have had a lot of trouble with them. Is it Pertronics I'm thinking about? I've only had one experience with converting to electronic ignition. It was on a 318 Dodge and used a common GM module and a standard coil. That thing fried several of those modules and many new ones weren't any good right out of the box. When that happened in the middle of Canada I'd had enough. I sold the damn thing. Lesson number one: Just because it's new it don't mean it's good and it's getting worse. For my flatheads I'll stick with the old tried and true points and condenser.
Going back to the first post, you said it was running fine till you went to lunch on a 200 mile or so trip. Before this it was fine, and it was still running till you start checking it. At anytime while checking it out or swapping parts, did it start and run? The initial problem still needs to be figured out, why did it start running rough after it was shut down? The no start you have now is from something you have done or the initial problem as worsened, you are going to have to back track to find at what point did it quick starting. I would start with new plugs, and a cap and rotor. Hot wire the ignition ( again ) to bypass everything. If that won't do it, replace the ignition module with points or new module. If it still won't start, timing, valve adjustment, or fuel quality has gone south.
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