Some of you have followed my travails. When I got Pickle a year ago she was stuttering and backfiring on the way home and it turned out to be a cracked rotor. Since then I have rebuilt the Webers, new SS fuel lines, new fuel pump, new fuel filters ,etc.

Well, she backfires occasionally , usually on even throttle when under some stress (going up a hill). Today, after throwing her through some severe twisties, she started backfiring horribly, then started to stall, and died. I opened up the distributor and wiped off the end of the rotor while looking for cracks. She fired right up and ran home perfectly...purring. I don't think the distributor had anything to do with fixing her, but not sure.

Almost seems to do with tossing her around. Float sticking? Dislodging crud (tank was clean...new filters, etc.) No freakin' idea really.

???

Hey Ken, but I don't remember, What motor and fuel system do you have in the "pickle"?

I would think that isolation of the issue is the first step to identifying the problem, BLAH. BLAH, TEXTBOOK, BLAH LOL!

Seriously, why do you think the distributor had nothing to do with the issue? (it was the only thing you touched before she ran well again, right?)

Did you smell raw gas when the car died and you messed with the dist? (maybe Ignition problem)

What do you have for a fuel pump, and do you have a Fuel Pressure gauge? (maybe Pump overheating)

Now, you say it happened after throwing the car in some twisties, has it ever happened before and was it after aggressive driving? Can you take the car to a large parking lot and sustain high lateral G forces to see if the problem resurfaces (maybe float issues, tank pickup/return line switched)
Sorry, I am just fishing right now and let's see if I can hook something.

Good luck.

Install factory D-jet ...

I agree here , and I see you said you have webers above, my error.

FI gets rid of all those issues (unless it is electrical) (and adds new issues, LOL)

How about SMS or Megasquirt, or an L-Jet system?

Were the backfires through the carbs or through the exhaust?

1911 cc (big bore on a 1.7), dual IDF 40s. New rotary fuel pump up front, two filters, cleaned tank, new SS fuel lines. Not really sure if it's popping through the carbs or exhaust. Will run flawlessly for many miles, then seems to backfire a little if I'm at...let's say 3,000 RPM, and start to go up a hill without much application of throttle. Never falters if my foot is in it. Today, all of a sudden, she went berserk...sounded like a machine gun of backfiring, misfiring, tach dropping and raising...it was hellish! Then she died. You know the rest of the story.

The little backfire is probably a small exhaust leak coupled with richish running with carbs. I get that all the time with mine.

I am guessing that your floats are set just enough wrong that they let your fuel bowl get dry when under heavy cornering. This would cause popping as the carb bank backfired when they went lean. Then that side died due to fuel starvation. After the engine died, the ignition was left on for long enough for the bowls to refill.

When you restarted, the carb bowls were full (or filled again), and your engine was happy for the drive home.

Just a theory... but it makes sense to me.

Zach

OK...took her out today to assess. Seems to have nothing to do with hard cornering. She idles fine. When running at about 2800-3000 RPM she's almost always smooth and trouble free. Then, all of a sudden, there will be two quiet little backfires, usually followed by more smooth running. Every once in awhile shell start to buck and surge... the tach going crazy and the LOUDEST multiple backfires I've ever heard...then she dies. Really thought Id blow the muffler apart...it was that loud. Wait a few minutes and shell fore right back up and usually run perfectly for another 10-20 minutes. Seems like she'd run all day without incident if I kept her at 4,000 RPM.

"the tach going crazy" Dead give-away your problem is electrical. Your ignition is grounding out and no spark is being sent to ignite the fuel. BOOM!!! Find your electrical ignition problem and you have solved it.

OK...where do I start looking? I'm an electro-moron. Is the tach really an 100% dead give away that it's electrical?

I'd still check your floats, to be sure that you are not leaning out. If you are running one side of the engine dry, that will cause the backfires out of the carbs as you go out of sync. Running lean could also harm your engine. The results of running like this make it worth checking out.

These engines with carbs are pretty simple. If it was a mechanical issue, it would likely be constant. But it might be worth making sure your dizzy is timed correctly, and that the collar is tightened down and that the foot that connects the dizzy to the engine is not wobbly on its shaft. You will need to pull the dizzy to check this.

It could also be that your plug wires may be arcing against the block or heads. This would pull spark and cause bucking and the loss of cylinders could cause the engine to stall. When was the lat time you replaced plugs and wires?

Check fuel delivery. If you have fuel filters going to each bank of carbs, try replacing the filters. Try blowing out the idle jets. make sure your fuel line is not pinching against something. Make sure you have enough fuel pressure. Again, this is getting back to one bank of carbs leaning out which can cause the popping.

Good luck!

Zach

Not much more than a shade tree wrench, but she starts easily...idles smoothly at about 900 RPM, and runs beautifully in between "episodes". I'm guessing the timing is fine. In fact, I'm assuming everything is fine with the tach based on that evidence. No?

If the plug wires were arcing, why would they be fine for 10-20 minutes of smooth, perfect running and then start to arc all of sudden?

Due to it's sporadic happening, I was thinking the floats were the most likely. Is the tach going crazy when it happens...bouncing like crazy and going form 0-3,000 and back again before dying, only indicative of electrical?

Also, don't think the backfiring is out of the crabs or I wuldnt have air cleaners or a deck...it was unbelievably loud and violent...can't over state that.

If you have a spare ignition coil, try swapping it. and even the condensor for the ignition. If either one starts to get flakey, I'd imagine your car would run as you describe.

Just my humble opinion.
-Robert

Both kinda new, but new parts can go bad too.

Particularly some of the newer replacement stuff. I have noticed that when I replace stuff that has been good for years but just old, I am getting a startling failure rate. I think some of this older stuff is being outsourced to China or the like...

Is your coil mounted to the tin? If it is, check to make sure that you aren't having the coil rotate and contact the tin. This shorts out the ignition and your tach will wave wildly and the car will gargle and backfire on the unfired fuel load.

The coil is mounted to the tin, but on a mount that holds it about 1/2" off of the tins. It's not super tight and can be rotated a little inside of the strap, but could never touch the tin itself.

I am actully fighting a similar problem, though it just happened today. I am starting to think that I need to replace my plug wires.

The car has been acting funny all summer. It seemed sorted when I took it to Cumberland but has been undeniable ever since I got back. I know I have an exhaust leak that is allowing backfires. But until today it had just been popping. Today I was getting the big loud ones and then shit idle and stalling engine unless I keeps the revs up. I think my #2 wire has a fault and is allowing an occasional misfire.

I am also not going to drive it again until. Have time to check valves. Was getting more valve train noise then I am used to and it has been harder to start then it was before Cumberland.

My plug wires (new) seem very loose, especially #4, but they are on...just lots of movement when you grab the end of the stalk which is so far away from the top of the plug itself. Guessing that's normal just because they are so far away from the end of the plug.

The tach needle waving wildly is a sign that there is an ignition short. Especially if it pegs and holds for a second or two. Check the integrity of your wires coming from the distributor condenser.

Are your plug wires supposed to go on the screw stalk or on the screw-on plug end? If you have the plug end off and the wires go onto the plug end, you will have loose plug wires.

Think about it. Why would a car run fine and then backfire? Your fuel system is pretty simple. You either have fuel and air or you don't. It seems to me you have an intermittent short in your ignition system grounding it out and interrupting the spark. Fuel loads up, spark comes back and BOOM!

Oh and Ken... That is a gorgeous car

Makes sense to me, and thanks for the compliment.

Ralph's in Owings Mills. Just get a pro under the hatch.

No challenge...no learning...no satisfaction of accomplishment.

.......Based on what you have said...(runs fine at under 4000 rpm)...and your previous under hood excursions,,,,I think that your troubles are all in the distributor....it,s intermitently grounding out, or the advance mechanism is sticking and not advancing.....or.....sticking in the advanced position....It may be time for a new distributor....They do wear out.

No...runs fine at all parts of the curve until it starts doing its funny business. THEN, if I let it go back to idle or keep it at 4,000 and above she will recover.

ROB WAS RIGHT. I went through everything on or near the dizzy, and noticed the condenser was touching the support for the accelerator cable. I moved it away. Also made sure all of the wires to the coil were tight. Then I ran her in the garage. 5 minutes at idle, 5 at 2,000, 5 at 2,500, 5 at 3,000 and 5 at 4,000. Twenty five minutes without even a hiccup or burp. So, I hit the open road for some "real life" situations, trying to see if bouncing around and putting a load on the car (hills and turns) effected her. Well, she did make her occasional small backfire once in a while, but she seems to be back to normal. Drove her another half hour. Couldn't have done that yesterday without crapping out 2-3 times after violent (and I do mean violent ) bucking and explosive backfiring.

Good Job Ken.

now bring it to Fells and we can drink a beer to celebrate

I am going to have to check this o mine.
Zach

Even thought the insanity has been cured, she still does backfire once in awhile, and I've isolated the circumstance. Maybe some Carb guru can enlighten me as to what might be the problem:

I'm doing about 2,800-3,500 RPM and slightly let off the gas...maybe to cruise down a hill or just coast along. If I then give it slight throttle, it'll most likely backfire. If I give it more than slight throttle, it does not. Any clues there?

there ia a guy in highlandtown tht is a real good friend of mine. He has a shop and will most likley put it on a lift and blow smoke up your tail pipe for nothin. let me know if you wanna do it and i will give him a call.

Jimmy (Dean Street Auttomotive)

I think you have a leak near the head probably

Sure...thanks!
Ken

Exhaust leak ...

Really? I thought exhaust leaks showed up on decel not on accel? Am I wrong about that (like many things automotive)?

Yes, correct. And from your description, you are coasting (decel) before the backfire ...

That'd be a ticking noise on accell(if it sounds like it ate a pot of beans...loose head
backfire

I can see where you got that but I specifically said, "If I then give it slight throttle, it'll most likely backfire", which makes me think it's not exhaust leak since it is doing the backfire upon application of throttle...mild acceleration. Does not do it on decel or heavy acceleration.

A small fart or two on slight acceleration only after she's been riding along at steady throttle. Never under heavy acceleration and not under deceleration.

And i specifically read that part ...

Mild acceleration after coasting can still be an exhaust leak.

OK...is blowing smoke up my ass...I mean exhaust...a decent way to find it?

Yes. Just remember that some of the valves will be open, so whatever you blow in there better not be bad for your drive train. Some people use a shop-vac run in reverse, but i'd be afraid to get all kinds of dirt blown into my cylinders that way.

Thanks.

Well...filled her up and added a half can of Valvoline Water Evaporater. She's MUCH better....could only get her to back fire once. Same circumstances...applying light throttle after a steady throttle . Did it before she was warmed up too (Webers...no choke...chilly out). Usually she'll do this a dozen times on a similar twenty mile journey. I'm thinking (fingers crossed) that she may be "healed".

They have a way of teasing you Like I said in another post, only miles will tell...