Popping sound in exhaust

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dart_68 said:
When it was popping it ran so bad that it wouldn't idle on its own. I had to keep blipping the throttle to keep it running. Once I pulled the Vcan it didn't pop any more and got it to run fairly smoothly. It was only then that I could get a good timing read.
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good but with 40* initial advance right? which is wrong
 
lilfontleroy said:
good but with 40* initial advance right? which is wrong
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Yup. Runs pretty good at idle but the timing light shows 40*. I put a timing tape on the balancer and made sure the balancer hadn't slipped before I put the tape on.
 
dart_68 said:
Yup. Runs pretty good at idle but the timing light shows 40*. I put a timing tape on the balancer and made sure the balancer hadn't slipped before I put the tape on.
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I'm telling ya, you're 180 off on the dist.!! just because you can, take the distributor out, spin the shaft 180 degrees and put it back in
 
lilfontleroy said:
no way not no how?
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A long time ago I had a dizzy in 180* backwards on some engine I was working on. The engine would putter but would never start. With the dizzy off 180* the engine just can't get the fuel/air and spark together at the right place and time.
 
Been following this thread and i'm pretty stumped as well. The sound your engine is making is exactly like when my cousin got his 440 '72 Polara back from a shop that got the firing order wrong; some of the cylinders were firing way early on the compression stroke trying to push the engine backwards, you could hear and feel a hard "THUMP" or two on every revolution.

Also every time I accidentally put in a dist. rotor 180° out the engine wouldn't run at all, just belch huge fireballs out the carb while cranking.
 
MopaR&D said:
Been following this thread and i'm pretty stumped as well. The sound your engine is making is exactly like when my cousin got his 440 '72 Polara back from a shop that got the firing order wrong; some of the cylinders were firing way early on the compression stroke trying to push the engine backwards, you could hear and feel a hard "THUMP" or two on every revolution.

Also every time I accidentally put in a dist. rotor 180° out the engine wouldn't run at all, just belch huge fireballs out the carb while cranking.
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If you take into account that the initial timing is @ 40* plus the vcan...there was so much advance that it probably was firing the wrong cylinder. I've disconnected the vcan and it runs with no popping and will idle fairly smoothly at 800.
 
dart_68 said:
If you take into account that the initial timing is @ 40* plus the vcan...there was so much advance that it probably was firing the wrong cylinder. I've disconnected the vcan and it runs with no popping and will idle fairly smoothly at 800.
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Gotcha, so it won't idle with less than 40° initial?
 
MopaR&D said:
Gotcha, so it won't idle with less than 40° initial?
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If that's a fact:
then I'm pretty sure the valves ain't working right.
The thing is, at idle, the Vcan is not working anyways if on the sparkport. And if on the sparkport,with a properly timed cam and fully functioning valves, it will be at least 1500 to 1700, in Neutral, before any signal at all will appear there. And the signal is usually too weak to operate the Vcan, until a lil later bringing in just one degree at a time, to peak at somewhere after 10" vacuum.
It sounds to me like the throttle is waaaaaaaaaay open, and the idle is still waaaaaaaay low, and that only happens, in conjunction with mega idle-timing, if the cam is running retarded.

Unless maybe you have a pair or two of plugwires crossed; each pair on a different crank revolution. Lots of guys get 5 and 7 crossed,which are on the same crank revolution. So now you have a V6 but at least one of those is firing on an intake stroke sending fire into the intake . Of course this destroys the manifold vacuum, and with that, the engines power; and so you have to crank up the idle speed to keep it running.
Imagine a second pair of consecutively firing cylinders are crossed up. If you have a second pair on the next crank revolution doing the same thing, well now you double the trouble, and have to kick in some advance to keep it running. Now you have a V4, but the engine is fighting those two backfiring cylinders, so it's a really low-powered V4 with way too much timing,way low manifold vacuum, and a waay increased curb-idle screw, and popping in the intake as the fire lights whatever is in there.Of course the unburned gas from the non-firing cylinder is collecting in the exhaust system, and is also popping every time it catches fire.
You can only screw up in pairs. 5 and 7 are common cuz they run next to each other on the engine, and also in the cap. No others do that.
Even just 5 and 7 , when it happens, makes a miserably running engine. Imagine two other successively firing cylinders doing some kind of dance.
I'm just speculating, as to 2 pairs crossed,as opposed to one pair; cuz one pair I know about. Two pairs, I have managed to avoid all my lifetime. A retarded cam I have also experienced... more than once,lol.
Just to be clear; the firing order is ; 1-8-4-3-6-5-7-2, the first 4 on the one revolution, and the second 4 on the next revolution.
Put a vacuum gauge on the intake at idle; it will tell you amazing things.
or, just start pulling off plug wires, one atta time, until the popping stops.This is called isolating the problem cylinder.
 
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dart_68 said:
When it was popping it ran so bad that it wouldn't idle on its own. I had to keep blipping the throttle to keep it running. Once I pulled the Vcan it didn't pop any more and got it to run fairly smoothly. It was only then that I could get a good timing read.
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With the v-can attached to the intake port, you likely had 60+ degrees of advance.... no wonder it mis-fired. The throttle blipping reduced the intake vacuum level level for a moment, the total advance probably dropped to the 40's-50's range, and the engine would fire properly and smooth out for a second. If the v-can had been attached to ported vacuum, then you never would have had that amount of over-advance at idle.

Now it's time to reduce the advance and see if you can start tuning the carb settings.
 
I saw mention of idle screw and rich plugs.
Too much transfer port showing.
I dont consider it an idle screw. More like the base setting.
Idle is done with timing and mixture screws.
 
Update:

I got the initial timing down to 12* BTDC. I had to fiddle with the mixture and idle speed screws to get it to not load up. I'm thinking that the throttle blades were open too much but I couldn't turn speed screw down. What I ended up having to do was turn the mixture screws all the way in. The engine sped up then I turned the speed screw down to bring the idle back down to ~750. Then backed the mixture screws out till the engine sped up and then backed out the speed screw. Eventually I got it to idle where it will die if I close the mixture screws. It likes it best at about 3/4 turn out.
 
dart_68 said:
Update:

I got the initial timing down to 12* BTDC. I had to fiddle with the mixture and idle speed screws to get it to not load up. I'm thinking that the throttle blades were open too much but I couldn't turn speed screw down. What I ended up having to do was turn the mixture screws all the way in. The engine sped up then I turned the speed screw down to bring the idle back down to ~750. Then backed the mixture screws out till the engine sped up and then backed out the speed screw. Eventually I got it to idle where it will die if I close the mixture screws. It likes it best at about 3/4 turn out.
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You see what yur doing here?
You are trading transfer slot fuel for mixture screw fuel and twiddling the speed screw to make it work. This is normal. And it's a good thing that you started with 12* of timing, because by 18* it won't work any more, the transfers will probably be too far closed. Now you can probably hook the Vcan back up...... to the SPARKPORT,this time,lol. Then rev it up to 2200 to 2600 and see how much Total timing you have WITH the vcan.

As for loading up; something ain't right. I had a 292/292/108 Mopar cam,that would idle down to 550 with a clutch, and it pulled itself along in 10.97 starter gear, at 4mph like that; on flat level, hard pavement. To do this I had to dial back the idle-timing from 14 to about 5.
What's yur water temp; mine was 207*F
 
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AJ/FormS said:
You see what yur doing here?
You are trading transfer slot fuel for mixture screw fuel and twiddling the speed screw to make it work. This is normal. And it's a good thing that you started with 12* of timing, because by 18* it won't work any more, the transfers will probably be too far closed. Now you can probably hook the Vcan back up...... to the SPARKPORT,this time,lol. Then rev it up to 2200 to 2600 and see how much Total timing you have WITH the vcan.

As for loading up; something ain't right. I had a 292/292/108 Mopar cam,that would idle down to 550 with a clutch, and it pulled itself along in 10.97 starter gear, at 4mph like that; on flat level, hard pavement. To do this I had to dial back the idle-timing from 14 to about 5.
What's yur water temp; mine was 207*F
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Water temp is just about 190*. Purhaps "load up" is not the right term. It was running supper rich and fouling the plugs (gas fouled, not oil fouled) and putting out black smoke. I'll check tomorrow with the vcan hooked up to the sparkport and see what my total advance is. Thanks for the input!:thumbsup:
 
dart_68 said:
Water temp is just about 190*. Purhaps "load up" is not the right term. It was running supper rich and fouling the plugs (gas fouled, not oil fouled) and putting out black smoke. I'll check tomorrow with the vcan hooked up to the sparkport and see what my total advance is. Thanks for the input!:thumbsup:
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At idle? Then something is wrong.
 
Swap your PV out for a plug. Check your wet fuel-level. Look down at all your butterflies front and rear; the valves should not have fuel on them while idling. Close your mixture screws up to 1/2 turn and do not change the speed-screw setting, nor the timing.
Go to the back of the car and put your hands over the tailpipes, in a modest effort to keep them closed. You should NOT feel any tendency for the pipes to suck your hands onto them; only pressure. Your pipes must be leakproof for this test to work.
Now check for too rich out the tailpipe.
Not smoking? pressure test your extracted PV, and replace if the diaphragm is perforated.
Still rich? IDK, you are running a PCV right? If not, get-R-done.
Still smoking black? Ima guessing your ignition is weak, or your plugs are beyond saving.
After that IDK
With the PV plug in there, you will not get much over 1/4 throttle, to perhaps 10" of vacuum in second gear. If you want to you can do some power roll-ons with a vacuum gauge on the windshield. Get her up to ~2200 in second gear and let the speed stabilize. Then gently waffle the gas pedal down from the stable cruise vacuum, whatever it is, to between 12 " vacuum and 8" vacuum. Somewhere in that range the AFR is gonna go lean, and the engine will complain about it. Keep waffling the peddle gently until you find the lowest vacuum that the engine is still happy with. And that will be the PV to install. I'll go out on a limb and say you need a 10.5 ,lol
That's all I got
 
AJ/FormS said:
Swap your PV out for a plug. Check your wet fuel-level. Look down at all your butterflies front and rear; the valves should not have fuel on them while idling. Close your mixture screws up to 1/2 turn and do not change the speed-screw setting, nor the timing.
Go to the back of the car and put your hands over the tailpipes, in a modest effort to keep them closed. You should NOT feel any tendency for the pipes to suck your hands onto them; only pressure. Your pipes must be leakproof for this test to work.
Now check for too rich out the tailpipe.
Not smoking? pressure test your extracted PV, and replace if the diaphragm is perforated.
Still rich? IDK, you are running a PCV right? If not, get-R-done.
Still smoking black? Ima guessing your ignition is weak, or your plugs are beyond saving.
After that IDK
With the PV plug in there, you will not get much over 1/4 throttle, to perhaps 10" of vacuum in second gear. If you want to you can do some power roll-ons with a vacuum gauge on the windshield. Get her up to ~2200 in second gear and let the speed stabilize. Then gently waffle the gas pedal down from the stable cruise vacuum, whatever it is, to between 12 " vacuum and 8" vacuum. Somewhere in that range the AFR is gonna go lean, and the engine will complain about it. Keep waffling the peddle gently until you find the lowest vacuum that the engine is still happy with. And that will be the PV to install. I'll go out on a limb and say you need a 10.5 ,lol
That's all I got
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"Look down at all your butterflies front and rear" - did that fully expecting to see the butterflies wet or boosters dripping. Nope. I even pulled the squirter to make sure the weight/valve under the squirter was there. It needs to be there to prevent the passing air from pulling fuel from the squirter. Float level was correct and fuel pressure is 6 psi.

Now,
It WAS putting out black smoke but you could barely see it and then after replacing the PV and fiddling with the idle mixture and speed it stopped smoking. I suspected the PV and replaced it as I didn't have a viable way to test it. The motor pulls 14" vac @ idle and the PV that was in it was a 6.5 so I replaced it with a 6.5. I haven't been able to drive it so I don't know what vac it pulls at speed under load. I am running a PVC, on one valve cover and a breather on the other.

I don't have a way to actually measure A/F ratio so I'm going to replace the plugs (or maybe a couple of them for now), run the motor and see how the new plugs look. If they look good I can move on the the next set of chores to get this car driveable.
 
My first guess would be problems with the carb and sounds like it has fouled the plugs
 
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