Hey guys, I have posted a question or two about this "problem child" of an engine before, so here goes another. I really need some advice!!!

Here is the problem: 71 383 Charger SE 2brl, all stock, motor looks virgin. Bought non running so I dont know any history. The problem is that I cant get it running successfully. At TDC, I have never got it to fire/idle. It will crank a few seconds, then make a poping noise, then I see smoke come from the side of the engine??? However, strangely enough, at 180 out on the distributor, it will run and idle. BUT, it will backfire through the carb (not terrible when just idling), but as I increase the throttle, it gets pretty violent. Ironically, I thought for a long time that 180 off (firing #6 at TDC) was the correct location, as it was the only way it would run? So, in short, I have an engine that at #1 TDC has yet to fire, and only backfires through the exhaust (I think), but will idle at 180 off (#6 firing at TDC), but will backfire violently through the carb especially as RPM's increase.

Here is what I have done: Engine had sat for a long time (10+years), so I pulled all the plugs and marvel mystery oiled the cylinders, let sit. Unhooked the fuel line at the pump, and am running it off new gas in a gas can. I then replaced all the plugs with new. I then put new wires on. I also primed the motor (dist went back in exactly as it came out). I replaced the points/condenser/cap/rotor). All those steps did not solve anything, the car has run the same (all steps done seperately, and I test ran the car in between, nothing changed). I ran a compression test, and found 125-140 in all cylinders. I then thought it must be a skipped tooth on the timing chain, so I pulled the front cover and looked. Stock nylon gear was missing some of the nylon, but timing marks were still lined up. I replaced the timing chain, and tested the motor, no change! Just to save some obvious questions, I have triple checked the firing order, it is correct. Dist spins counterclockwise. I installed the timing chain correctly (the new and old ran the same). I gapped the plugs and points correctly, it has always run the same. Moving the dist a few degrees either way never changes anything (the carb backfire), etc...

Bottom line, I have been tinkering with this engine for a month or two now (off and on). I find it weird that it fires right up at 180 off and when idling a 700 rpm or so, you can barely tell anything is wrong. I burned nearly 2 gallons of gas trying to adjust stuff, and the whole time it was 180 off. When I pulled the timing cover, and lined the timing marks up (upper gear at 6 o'clock and lower gear at 12 o'clock) I then realized that it was firing #6 cylinder at that moment. So, I advanced everything 4 posts forward on the dist (firing order is correct) and it was then lined up to fire #1. Would not fire at #1. Just for kicks I moved all wires back to make it fire 180 out on the dist, and it runs. In fact, through the process, I have changed firing positions on the dist from #1 to #6 and it only runs when it is at #6? Like I said, it just seems like it is building pressure or something when I have the firing position correct, but never fires at #1 TDC? But also remember, that when it does fire at 180 out, it runs poorly, especially as the RPMs increase, and it backfires violently through the carb.

Looking for advice on what to do next, or if anyone has ever had a problem similar???

THANKS EVERYONE!

Can you line the timing marks up at TDC then take a pic of which wire the rotor is pointing at? Also, what did you mean by smoke coming out the side of the engine??

Hello. When I pulled the timing cover, I cranked the engine over manually, with the stock chain still on it, until the upper sprocket had its timing mark at exactly 6 o'clock position, and the lower sprocket at exactly 12 o'clock. When that happened, the balancer read TDC 0' on the timing mark. (the keyway was approx 1:30 o'clock position on the crank, and the dowel pin on my single bolt cam was appox 4 o'clock). So I knew that at least the timing chain had NOT skipped a tooth, it was correct. At that point I pulled the old timing chain off and replaced it with new in the exact position. So, in short, the timing chain should be correct, as the engine has run identical with both of them on. As far as the distributor, originally, when I lined up the timing marks as stated above, it was pointing at #6 wire. That is the only way it has ever run though. So, knowing that it should be pointing at #1, I changed all the wires so that the dist was pointing at #1 (and the firing order was correct). I then reinstalled the cover/balancer, and tried to fire the motor. I would never fire (and has NEVER fired) in this position, which should be correct. For fun, I advanced all the wires back again to #6 firing at TDC and it will start/idle, but as stated, backfires violently through the carb, especially as RPM's increase. As far as smoke, what happens when the engine is at what should be correct, #1 at TDC, it just cranks for a bit (10 seconds or so), then something happens and sounds like a pop, and I noticed smoke bellow out from somewhere? Seemed as if it came from the pass side of the engine. Just a quick puff, dont know if it is even important. Buy I will say, as it cranks, it doesnt do so freely. The resistance of the engine will change a bit and it seems as though pressure is building, and that "pop" releases the pressure or something? I feel like it wants to backfire (or explode HAHA).

when the timing marks are lined up dot to dot(cam gear at six o clock and crank gear is at twelve o clock) number six should be firing not number one. confuses alot of people. as far as backfiring out the carb,could be a stuck or bent valve.

Good to know! I guess that would explain some stuff, but yeah, the backfiring through the carb is an issue now? Should I just pull the heads? Can I pull all the rocker gear and look for any tell tale signs of bent stuff? Would my compression have shown 125-140 on all cylinders with a bent valve? Confusing!

First, the dist can go in 2 ways, 180 out or straight up. That's what's causing the "runs with #1 at #6 position".
You can bring the motor up to TDC #1, take the dist. out and then install the dist. so the rotor points to the # 1 position.
Then wire the cap to normal firing order.
Leave the cap off, and connect a plug to the coil wire. Ground the plug body.
Next, roll the motor back to ~6 degrees BTDC.
Turn the ignition on. twist the dist. back and forth until you can get it to spark. Note the location, and tighten the dist. Turn the ignition off and install the cap and coil wire normally.
This is called dead timing, and should get you in the general area for running.
Other things to check are that the rotor can twist and spring back (mechanical advance), the coil develops a good spark, and that the firing order is correct again.
Pinch off or block any vacuum lines, and see if it will run. Then check for vacuum leaks. Check the timing if possible.
You might have some sticky valves, which can cause popping, so try to find a spot where it's running fairly smooth, and let it warm up.
Good Luck

OK, I'll take a stab at this...First off, I'm a 31 year veteran auto tech, so some of the stuff I'm gonna say may sound strange, and some may sound like a repetition of stuff you've already done. I'll try and keep it simple, here goes...
The only way that a backfire can occur through the carb is if there is a leak in the combustion chamber or a very lean air/fuel mixture. Lets assume the former for now. A leak of compression can happen one of many ways. I will list a few, but even though you said you checked these items, I'm gonna list them anyway. It is possible that you overlooked something, or misinterpreted your findings. Somehow ignited air/fuel mix is finding its way back up to the carb. The only way this can happen is if a valve is either open when it's not supposed to be, or not sealing properly. Thus you may have: A burned valve, excessively worn valve guides, improper valve timing, a broken valve spring, incorrect ignition (firing order or timing), wrong pushrods or lifters, etc...Therefore, we must confirm the proper sealing of the combustion chamber. The only way to do this properly, is to perform a "cylinder leak-down test". The tool can be purchased from Snap-On and other suppliers, and will tell you if you have a proper seal in the combustion chamber. Compression tests are OK for most basic diagnostic needs, but a cylinder leak-down test is much more accurate and informative. Even though you had somewhat acceptable compression readings (I like 140 to 150), there still could be a sealing problem. Some valve problems tend to diminish at higher RPM's (such as a small piece of carbon or a very slightly burned valve face) and others will get worse (such as a broken valve spring). The readings will be in percent. 10% loss across all 8 cylinders is about the max you want to see. More than that...you got a problem.
One other thing, contrary to popular belief, the engine could care less what towers the plug wires are inserted into. As long as the firing order is correct beginning with cylinder #1, and the piston gets spark when near TDC, #1 could be any tower! You see, it is possible that somehow the distributor was removed and installed such that the cap marking of "#1" no longer jives...So instead of fiddling with dist position, lets do this (much easier): Pull #1 plug (#1 is always the plug closest to the radiator, in this case the front plug on driver's side) and turn engine over with a breaker bar until you hear air rushing out (have an assistant hold their finger overthe hole) and slowly bring the piston to TDC. Next pull the dist cap off and note the rotor position. If needed, turn the dist slightly so the end of the rotor lines up with the nearest tower. This is now #1 regardless of what the dist cap says. Place number 1 wire in this tower and then follow along counter-clockwise in the following order: 18436572. 1357 on driver's side 2468 on passenger (from the front of course). Crank the engine, and if needed, move the dist SLIGHTLY one way or the other until it starts. Of course, all of this assumes that the cranking voltage is good, as is the coil, and you have adequate fuel delivery, etc, etc....

Good luck!

Hello everyone. Okay, a little update on what I did. By the way, I forgot to mention I put on a new coil and ballast resistor. They too did not produce any difference. Also, once I got the engine up and running (weeks ago), I twist the distributor back and forth a few degrees, but it never changed that backfiring through the carb, or its intensity for that matter. At one time, I did let it run for a period of 15 minutes or so. I was hoping it needed the lifters to pump up or something, but it didnt change anything. I now think that I had the firing position and firing order correct all along. For a while I thought I was 180 out. The issue I see is that it seems I am not getting a valve to seal? That is just what I thought. For quite some time I thought I had skipped a tooth on the timing chain, but that was not the issue. I think I will pull the valve covers and pull the push rods out for inspection next? If anyone thinks that is a waste of time, please let me know. THANKS!

check the firing order and make sure you don't have the wire for 5 and 7 swapped .

if you have compression in all cylinders then you should not have any valves stuck open but just for grins you can pull the valve covers and turn the engine over by hand , go thru each valves opening and closing cycle , if you have a valve stuck open it will show up as a very large amount of lash when that cylinder is on the base of the cam lobe .

A31HPAxle, there's one thing you left out. Sometimes a FLAT (worn) EXHAUST CAM LOBE can cause backfiring, (at least on certain cylinders) because the flat lobe acts like a "cork" because it's not opening, and will cause the cylinder pressure to blow up back out the intake when that valve is open. This of course could be caused by other things like a bent/ broken pushrod.


Let me add a little to the "static" timing method. Someone else was indeed correct about the cam drive marks. When many V8 cam drives are "lined up" according to the book, they are "no 6 ready to fire" and not no 1.

Hell, when I got my first 57 Chivvy, I didn't even KNOW there was a "certain" way to install a distributor.

Pull no1 plug, Rotate engine with a remote starter or wrench, holding your finger in no1 and watching the timing marks. As the marks "come up" on the wheel, and as your finger gets blown out of the hole, THAT is approaching no1.

Stop the wheel, at , anywhere around 10BTC, 15 BTC.

Install the dist, and note where the rotor points, THAT will be no. one.

Mark the rim of the dist. to match the no1 tower

Rotate the dist COUNTER clockwise to close the points. SLOWLY rotate the dist CLOCKWISE while doing one of the following:

With a 12V test lamp from coil neg. to ground, move the dist until the lamp lights --or--

leave the ign on, and watch for a spark. Easy way to do that is stick a spare plug on the coil wire, to ground.

THIS METHOD if properly done, should allow the car to start right up and run.

ALSO, "spring" the rotor, to check fo proper freedom and operation of the advance and springs. You should be able to "spring" the rotor CCW and it should spring freely right back.

Also, you might find a troublesome cylinder by getting it running as well as you can, pull the boots loose at the dist. towers, and then push a prod--test lamp or small screwdriver, etc--down between the plug wires and a clip to ground. You can now ground one cylinder at a time, and it might tell you which "one(s)" are backfireing, then check them out for valve trouble, etc.

Also check the carburetor accelerator pump shot. Do you have 2 streams of gas squirting AS SOON AS you move the throttle open ever so slightly? You can check this with the engine off since it is backfiring. If not you will have to rebuild the carburetor(if carb not rebuilt)and/or adjust the accelerator pump.
Ron

At the end of his first post he stated -

Quote:

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"But also remember, that when it does fire at 180 out, it runs poorly, especially as the RPMs increase, and it backfires violently through the carb."

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I take that as he tries to open the throttle, it starts to backfire?
Ron

Hello. At idle, it runs, but not completely smooth. I can hear a slight pop every second or two, but it is not that major. As I kick up the throttle, it gets much more violent. As the engine revs up, its like "BAMBAMBAMBAMBAM" through the carb, fast and it gets EXTREMELY LOUD!!!

Do you have adjustable rockers?

Hello everyone, just an update. First, thanks to everyone who helped with this situation. I finally pulled the valve covers and turned the engine over. Noticed that the #2 cyl exhaust rocker was staying stationary. So, I pulled the dist and shined a light down there, #2 exhaust lobe was flat. That seems to be the problem. Hopefully its my only problem. Thanks again!

Yep - It isn't just a replace the cam and lifters deal. You had batter pull the engine and completely disassemble and clean it up from all the filings that are in it or it will be a short lived engine again.

hahaha I say stuff just to hear ya Jon. Really if you are talking about pulling the motor down and doing a complete rebuild I'd say nah. Especailly if it's (now don't get angry John) a stock non-anything 383. Clean it out as best you can. You can even drop the pan and re-place the rod bearings. All I did was flush it real good and then run a magnet everywhere. Then I replaced the lifters and cam. Both cams were 509's in the late 90's. Must have been a metal defect or something.
I have always run a magnet in my pan for just such emergencies.