Motor is a 59AB in a 29 Tudor was running perfect but has developed a stumble and hesitation on acceleration. Idles perfect, can hear a valve tick on the right bank but I don't think its a stuck valve due to good compression. The setup: Triple 97's on top center primary outers dump on WOT with new Sharps heads. Have not opened the carbs yet. Compression 125 across the board (one cyl on right bank slightly lower at 113) New Stromberg Dizzy, plugs, wires, cap, rotor, coil all new as well. Plugs have carbon fouling. Also doesn't seem to change much when pulling plugs to do a balance test. Timing full advance or full retard will make the hesitation and popping better or worse but does not make it go away. FPR set to 2-2.5 PSI Gauge is on the firewall, so I can't tell if it starves under acceleration but revving with no load the pressure stays consistent. Fuel line is spliced in one spot from the pump to the FPR, but I don't think the slight reduction in the line from the coupler would cause the popping. Transmission is a T5 manual and works as it should. I run 87 Octane, have not tried running higher octane. I am digging into vacuum next, as well MMO down the carb. Any suggestions are welcome.
Seems like you covered most bases. Have you thought about a leak down test on the low cylinder? Maybe just a bit of poor sealing, little Un burnt fuel reignited in the exhaust.
Distributor, carbon tracking ? Point gap ? Just went through the same on my A , turned out it was either the point gap or 2 bad plugs ( though fairly new ) . Was popping on on both sides of exhaust . Vacuum was a little low but steady , reset points and now have 17” .
I am noticing that the primary carb has some seepage from one of the three plugs, but it's not a leak, just a little gummy on the intake. Also, not sure how or where to check for manifold vacuum. Not sure who makes the intake, it only has a serial on the front right corner but no other markings.
No points. Its a brand new Stromberg e-FIRE dizzy with timing adjustment on the side. Stromberg wires and Autolite 405 plugs recommended by Sharp. I installed the heads back in April and car ran perfect then. Have rechecked bolt torque several times.
Check dizzy cap for crack or carbon tracking. Check intake bolts. Possibly pulling a vacuum leak. I don't like the ticking. Maybe a valve spring. Just Suggestions
Missed the ticking, could be engine to manifold/ header leak causing popping? Would not explain a lower compression reading though.
Nice looking engine! Sounds like you have the right approach to diagnose the problem. I have nothing to add except, that the ticking and popping in the exhaust would lead me to believe there is a valve hanging up from time to time. MMO may be the fix. Good luck!
Pulled the primary 97, has a recent rebuild and all jets are clear and nothing stuck. Accelerator pump felt was a little wonky, but went back in like it should. the power bypass was free and clear, and both jets passed a pin through them but I cleared them with air anyway. Going down the road she stumbles and hesitates, choke makes it worse, thinking about going back to timing but AFAIK these e-FIRE dizzys need to be timed by feel not a light. One thing I am wondering... I have a ballast resistor installed after upgrading to the efire, and the directions say you can run with or without. I'm wondering if without I would get hotter spark? Before I rip anything else apart I am going to get some MMO. Will have to be tomorrow though, have dinner plans with the wife tonight.
OK.. pre dinner update: Jumping the resistor definitely helped with power. She rips now. However, popping is still there, on acceleration, deceleration and mid throttle. Goes away at WOT, but in this death trap.... its hard to hear the motor even though the pipes are baffled. Timing changes idle and behavior accordingly but there is still popping adjusting in either direction. I'm still going to try the MMO tomorrow, will update with progress.
Popping through the exhaust is a classic sign of a stuck valve. There's a lot going on.... The Stromberg E fire....Very mixed opinions/experiences about these. Ticking on the right side.... Popping on the right side... Lower compression on one cylinder....on the right side... Consistent popping after playing around with the ignition and carburetors... I'm thinking this is mechanical. A Sticky valve.... Consider this...Cranking speed in a compression test is very slow compared to running speed. At running speed a slow valve could act as a completely stuck valve. With that said.... Pop....miss....or a skip.... Listen to this. ^^^^^ This was Timing! I had tuned it by ear and off a vacuum gauge to where I "thought" it was happy. I put it on the light and it was way out. RPMs decreased and the tone of the engine changed. I don't have a comparison afterward. But in the video above the engine sounds " Tinny". As I did a running timing adjust with the light, It went from that "Tinny" sound to a "Low Rumble". That was it! Now more miss. It was just out of time. This is a 8BA and it's little different than your engine but the concept is the same. The E fire is not real popular on the Ford Barn..... Before I got into the engine I would try another timing adjust with a light. If I had a known good distributor I would replace the Efire and see if I still had the pop before opening it up in search of a stuck valve.
So went and got 2 bottles of MMO. One down the tank and half down the intake. Seems to have helped, but popping still there and low speed acceleration stumble/hesitation. Dizzy is running full advance which helps a lot. Full retard it pops more than my rice krispies. At this point, I think the only thing left is to pull the intake and inspect the valve train. Anyone have any other ideas? Or anyone know a flathead specialist in the New England Area? (I know of a guy in Amesbury Ma but he hasn't returned my messages.
It popped with the POS Pro Comp on there too and yeah... I am leaning towards valve train now that the MMO helped. I have a spare intake gasket, but a car show coming up a week from tomorrow... I may wait till after that to yank it apart.
I just put these heads on in April. I would prefer not to burn an $140 set of gaskets unless I need to pull a valve. Pulling the intake is fairly easy, as I do not have to remove the carbs. Pull the linkage, fuel lines, and take the intake off. Helps that I have a spare intake gasket too. Seems after a second dousing on the outer two carbs the popping has gotten worse. I have attached a link to a video if anyone wants to give a listen. Sorry for the absolute shit quality. You can hear it pretty good towards the end when I roll through the parking lot in second gear.
I think you probably know that one cylinder that is a bit low is probably your problem. This would be a good one to put on a scope to make sure your secondary wiring is good before you tear it apart.
Broken valve spring?? I had a similar problem on my sbc, spring had enough tension to close the valves while cranking (the ends had overlapped a tad allowing it to still work - weakly) to do a compression test, anything above the engine popped out the exhaust..
Check the valve lash. If The lash is tight, but not so tight that it holds the valve off the seat while cold cranking, the valve stem can grow enough in length while the engine is running to hold the valve off the seat.. also when the intake is off to check the lash, you can crank it over and watch the operation of the valves to make sure nothing is sticking.
You have ticking. I would pull intake and check valve adjustment first. Maybe there is a valve too tight as well as a loose one. Other then that as I suggested before a weak or broken valve spring or a warped valve.
First worth mentioning is the fact that Marvel in the tank will free up the valves. Sometimes you have to run a few tanks through ( for maintenance they suggest 4 oz per 10 gal. However to free up a problem you can go with a cup or even a pint. No harm in the tank. If that won't get it..... Try this Go to The Fordbarn (there is link someplace here) Register yourself there. You need the Early V8 Forum. Then look on the members list. Select the letter R. Find page 123 in the R section . Look for the bright blue roadster avatar. Ronnie Roadster works on these motors. He is quite accomplished. In fact he just set an official time with The Loring Timing Assn. of 207 mph in a mile and a half. Always a helpful voice ( try a private message ) and given your location you may even hook up with him.
Hi As a Troubleshooter I would start some with a change in fuel to another station and with a higher octane . Also I agree with Gary about the cylinder leakage test . Every flathead I've run successfully runs a little rich and this also helps cushion the valves which is important but back to your situation I've also had popping due to vacuum leaks on many multi carbed setups so get a can of Valvoline starting fluid ( it cushions valves ) and cupping your air filter area do spray around throttle base plate and around intake and disconnect any vacuum accessories you may have . If idle changes noticably well you'll figure it out . Once my 221 was spitting out both sides and the 97 I was running had clogged jet and took a couple cleanings of the float bowl then went away . Also suggest keeping an eye on primary resistor getting too hot
Ok I read through all replies and if it was me I would try another cylinder leakage test before going through the valve train teardown which is a guessing game of frustration . I would ditch the multi carb setup before hitting the valve train unless you mishandled your flathead and if that just have a seat in the garage and stare at it
Waiting on a leakdown gauge... here are the newest compression results except Cyl 5 because I was absolutly too lazy to pull the alt off. 1 - 115 2 - 110 3 - 105 4 - 120 8 - 105 7 - 125 6 - 130 Valve noise sounds (by ear) between 1-2. The rest of the train seems normal. Shes hesitating more than usual, but I haven't had a chance to drive long distances due to rain. By long I mean more than a few quick rips down the main road.
Bent #1 exhaust valve. Also capped off 2 of the trips and just running a center primary. Runs like a flat head should now. Thanks everyone!
I had the same noise years ago on my 47 ford with a flat head. Thought it was a valve or even spring, but turned out to be an exhaust leak at the head.
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