Bad engine miss

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One wet plug, would indicate no spark, - bad plug, - wire burned/arcing, or something in cap.
Plug being wet also indicates intake valve is opening, - no backfiring outta the carb, as happens when an exhaust valve isn't opening, would presume exhaust valve is opening.
I'd be looking at exchanging/replacing the plug to a cylinder that's firing.
Check/change plug lead, scrutinize cap and rotor.
jmo
 
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Inertia said:
Wish I had known you when my kids got into bikes, expansion chambers. ? ? ? Lol
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Yeah, 2-stroke race-bikes are a different animal. I work on those, but I don't engineer them. Guys used to bring me boxes of stuff and say, make it work, lol. I had a friend, smarter than me in that arena, who engineered the engines, and I just bolted it all together, and said "good luck". Cuz, as you know, that's 2-stroke racing, lol.
You gotta stay on the bike to win, and every young boy dreams of being first into turn one, and leading the race after that, lol. All 15 of 'em. Yeah it takes a lotta driver skill, driver power, and driver stamina, etcetera, but mostly, that first lap is all luck. One wrong bounce at turn one, and everybody goes down.

When my boy was around 12 or 13 I bought him a worn out Honda 4-stroke. It had a decent engine but the chassis was just bagged right out. We lived in a hick-town, in the country, with an old railroad track allowance about a block away. I told him to idle out there and go nuts, knowing that suspension would limit his exuberance.
Well it wasn't long and he was wheeling that lil 200 all the way down mainstreet. Criminy. Now I gotta make rules?
Next came stoppies with drum brakes. Then Poweslides. Every time I made a rule, he was like SmokyYunich, finding a way around them. Finally, he was a tad older and stronger and so, I said you know what; in two summers you haven't broke your neck yet, just go ride and don't let your mother see you. Shazzam, He was gone!
 
If you have wet spark plugs [ wet with gas, not oil ], doing a compression test would be at the bottom of the 'to do' list, not at the top of the list.
You may have a flooding carb that is causing wet plugs. You need to investigate why the plugs are wet. Wet plugs do not fire....they cause a bad misfire!!!
If you have installed new plugs, make sure the heat range is correct, not too cold. Should be a 5 in NGKs.
 
How did it run when you put it down?
Springer2269 said:
It ran fantastic, then life got it the way and it sat in a Florida garage untouched for 9 months to a year. When I pulled it out and tried to start it, I put fresh gas in it. Primed carb and started for a second and died. I determined fuel pump died so replaced it, put new gas filter and changed the oil. Turned the key and started right up but with a bad miss, I pulled the plugs and 6 were black with carbon and 2 were wet with gas not oil. Pulled the plug wires one at a time with it running and the second cylinder from the front on the passenger side made no difference in the motor and that was the plug that was wet.
I now thinking push rod, lifter or valve spring. Before I pull the valve covers I’m going to do the compression's test everyone is recommending. Engine only has 1800 miles on it
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Then I highly suspect you have no mechanical failures. Probably crud in the fuel system.
 
Springer2269 said:
I have a 71 Dart Swinger with a 360, it was in storage for about a year without being started. I put a new battery in and cranked it over with the coil wire out to make sure I had oil pressure. It would run pouring some gas in the carb but wasn’t getting any fuel from tank. I put changed the oil, a new fuel pump, spark plugs and a gas filter and it started right up. At idle it seems to have a little miss but when I drop it in gear it really misses and shakes the whole car. Cap, rotor and wires are ordered and hopefully they will solve the problem. My question on the passenger side exhaust tip it blows warm to hot exhaust but on the drivers side the exhaust is cool and not even warm. Am I right in thinking my problem or miss is on the drivers side? Also I did fill up with fresh high test. Thank for any ideas with my problem View attachment 1716331068
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Well I found the bad miss in my engine, now to figure out what caused 3 cylinders to bend the pushrods

IMG_8163.jpeg


IMG_8164.jpeg
 
Just a “fwiw”……..

The “welded ball” style of pushrods, which is what those appear to be, are usually just parts store stock replacement quality, which can be a step down from OE.

If you have an aftermarket cam and upgraded springs, they may not be up to the job.
 
4spdragtop said:
Valves too tight in guides?
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i kinda had that thought as well.

fresh build, clearance is a little snug. been sittin' so not a bunch of lube rolling around in there. come up and lean on it real good trying to get it started and something just sticks, valve's hanging there and the piston kisses it.

the valve stem heights would tell tale there, so at least it's a quick visual...
 
This is bad luck....
I've started untold amount of cars that hadn't been started in any range of a long time and never had that happen....
 
Now you guys have me scared, I’m going to do a lot more investigating before I put it back together. I didn’t build it so these are all valid questions. I’m pretty sure I have the build sheet from the guy I bought the car from. Thanks
 
Springer2269 said:
Now you guys have me scared, I’m going to do a lot more investigating before I put it back together. I didn’t build it so these are all valid questions. I’m pretty sure I have the build sheet from the guy I bought the car from. Thanks
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what're the specs on the motor.

specifically the heads...
 
I’d pull the springs off the valves that go with the bent pushrods and verify they move freely in the guides.
 
PRH said:
I’d pull the springs off the valves that go with the bent pushrods and verify they move freely in the guides.
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Exactly. I wouldn't be the least bit surprised to find a valve tight due to fuel varnish from sitting. Especially on a fresh build, where the clearance is much tighter than some 150k mile used engine
 
My uncle did the same thing rebuilding his 312 Ford T-Bird engine, he let it sit in the garage for awhile, and when he got it started, valves stuck in the guides
 
NC Engine Builder said:
Exactly. I wouldn't be the least bit surprised to find a valve tight due to fuel varnish from sitting. Especially on a fresh build, where the clearance is much tighter than some 150k mile used engine
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I had a slant 6 rebuilt from a '74 Valiant that had been sitting for a long time and fired it up. Ran great for about 15 minutes then started running very badly. Pulled the valve cover and had several pushrods bent. Bottom line was bad gas sitting in the tank was not flushed out and the fresh gas simply dissolved enough to go to the engine. Rookie mistake, as I was focused on the engine and not the fuel system as a whole. I pulled the tank and sent it to the local radiator shop where they boiled it out. I pulled the cylinder head and had it cleaned. Very much like putting sugar in the gas tank.
 
67Dart273 said:
I would not. I would first check compression and or leak down test. That is what they are made for--to do diagnostics without tearing into stuff and ruining gaskets, etc

Also a note about pulling wires. I recommend you do not. Instead, "rig" so you can SHORT the spark to ground. I used to work the dist. boots up away from the distributor, and insert small brads or paper clips down each plug tower, or use a very small thin probe. You can use a 12V test lamp (lamp not an LED) the spark will not hurt it. Then you can short each plug tower individually. WHY? Because when you PULL a wire, it creates a HUGE spike in voltage which can crossfire and lead you down a wrong path. Also with modern high power ignition, you can damage an ignition module when pulling a wire like that.

I also have, or used to have a pair of insulated fuse pullers for the large household cartridge fuses. You can loosen the plug boots, them get a grounding probe handy, and ease them part way off with your fuse pullers, then put the shorting probe inside the connector so it does not crossfire.
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Sounds like a lot of work. I hook up a timing light to each wirer and record the flash at each test. No flash, check, wire, plug and cap in that order. To test wire, I remove it and place it at another plug and cap setting, that I know was good to start with. Same with the plug. After wire test, swap out plug location. I always investigate before buying parts.
 
I got real lucky, I put the new pushrods in and the engine ran great.
It smoked for about 10 minutes but after a nice ride she stopped, I think the valve seals may have been dry.
 
Springer2269 said:
I got real lucky, I put the new pushrods in and the engine ran great.
It smoked for about 10 minutes but after a nice ride she stopped, I think the valve seals may have been dry.
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Great news indeed.
If one or any of those bent pushrods was an intake valve, the vacuum created inside the cylinder with that piston going down while the valve is closed, it's reported to be able to suck oil up past the rings. That can cause a lotta oil to get in the exhaust, to be burned up.
Vehicles with bad cam lobes/rockers often do same.
Drive it more often, lol, - don't run it for short periods, let it get good and hot to prevent condensation in the crankcase.
Good luck, - lotsa miles, with lotsa smiles.
 
Springer2269 said:
I got real lucky, I put the new pushrods in and the engine ran great.
It smoked for about 10 minutes but after a nice ride she stopped, I think the valve seals may have been dry.
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I suspect gas leaked out of the carburetor and hydra locked those two cylinders. You were very fortunate the pushrods were all it got.
 
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