weird smelling smoke!?! please help!

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dartkory

dartkory

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so I have a 318 with eddy heads thats running about 9.8:1 compression. I put a holley 670 avenger on months back and it made an amazing change in performance over my old edelbrock 600 cfm carb. so anyway's, whenever my buddies are cruising behind me they said when I floor it or just goose it a little it blows smoke that doesn't necessarily smell rich and for sure doesnt smell like oil but they said there is sometimes a very small tint of blue in with the smoke. they said the smell is indescribable almost as if im running a different kind of gas. any ideas? I checked my compression, all the cylinders are all the same, and im fairly certain its not the valve seals since the heads are brand new plus im not losing any oil. I also tried jetting down my carb but even going down one number on the primaries and secondaries made it start back firing a little out of the carb, so I went back to stock jets. My timing is 16 initial, and 42 total which seems a little high on the total side but I dont know how to make the total lower. one last thing, when I was running my cast heads my motor would ping a little so i was told to run cold plugs, but now that im running aluminum heads should i go back to a hotter plug? sorry for the novel. but any help would be greatly appreciated! thanks -Kory
 
You are running rich. You see a lot of souped up cars that smoke when you get on it. Getting the carb in tune is a never ending process sometimes. My Holley is causing the same problem. It is the carb the engine was dyno'd on and I am sure they tuned it for maximum power, but that has little to do with every day driving. I turned the mixture screws in 4 turns and still run rich. I have to check the jets and I am sure the venturis are too big. As for me, I will live with it because I plan more changes this winter and that carb is going away.

Question: with your timing at 42 degrees, which seems high to me, are you getting pinging or knocking? Are you running pump gas or racing fuel?
 
That title is too funny! I won't respond for fear of the ban.LOL
 
You took "snorkle" out of the title. I used to just put some gasoline on it to disguise the scent.LOL
 
Here is what I think is happening. so when you put the smaller jets in it you got a backfire out the carb? What i think is happening here is your running real rich, then you jet down and it leans out so now your idle fuel+the pump shot is not big enough. The pump shot squirts extra fuel when you change throttle position IE when you mash the throttle to the floor. Not enough fuel can give you a stumble or backfire. So I say jet down and give it more pump shot and see how that works out.


BUT, if you really want to get your carb tuned good, invest in a wideband o2 sensor. It will pay for itself in gas savings if, its running rich and you end up leaning it out and picking up some mpgs.


Also like said above, check your timing and make sure that is all good. BUT, I assume it was fine with the other carb and hasn't been touched, so it likely isn't the issue.
 
thanks for the input. mopar to ya, when I was running my cast heads it would ping but now that im running the aluminum heads it no longer pings. I just run pump gas. and so does anyone know if the colder plugs are ok to run or should i use hotter plugs? Sirdan, would it be leaning out even though it still smelled very rich? because when i went to the smaller jets it was as if I didnt change anything because it was still rich, and performance was about the same, it just did the backfiring thing. Thanks again. -Kory
 
When it did backfire. I'm assuming off idle if you floored it, it would backfire and hesitate then after a second it would go like normal?
 
Or, it could be that your baseline jetting is reasonable, and your pump shot is too aggressive causing momentary dilution of the oil on the cylinder walls, and a puff of smoke.

I'm betting the backfire is the 42 degrees total timing which seems like a lot for a 9.8:1 engine. To keep the 16 initial, and have less total, you'll need to reduce the amount of mechanical advance in the distributor. To do this, the slots in the upper advance plate need to be shortened either by welding and grinding or adding small stop screws.

Hotter plugs won't help, they'll just be impossible to read. If the plugs you have now aren't fouling, they're hot enough.
 
[QUOTE=Mopar to ya;..... are you getting pinging or knocking?

I think you should check this a little closer? Might not be bad enough to hear, but it will rattle the pistons enough to break the ring seal and that would give you your slight weird smelling (tinge of blue) smoke. I think the 42* total is too much......jmo.
 
sirdan, thats exactly when it happens. and fklskv, its not using any coolant. and c130 chief, im gonna attempt to fix that total timing. thanks for the help. Im hoping after i jet down my carb and fix my timing it will run a little better.
 
so I have been looking at after market distributors so I wont have to rig my stock distributor. do you guys know what would be a good distributor to use that I will be able to adjust the total timing with the bushings or springs? I have been looking at the MSD billet 8534 distributor, what do you guys think?
I while back I remember getting a msd distributor and hooked it up to the harness on my msd digital 6 box but could never get it to work so I returned it. Do any of you have the install directions so I can make sure to do it right? Im pretty sure the new distributor will come with em but just to make sure. thanks -Kory
 
Magnetic ignition triggers, like OEM Mopar are typically Hall effect. As opposed to optical like Mallory Unilite or some Crane retrofits.
 
so i just checked my total with the vacuum advance hooked up and it was at 54!! that cant be good right?
 
Total should probably be around 32 degrees with that compression and set up, but I will defer to those who know better. I have 11.8:1 compression. When I tune it down to run on pump gas I run around 26 to 28 degrees total timing. When I run race gas, I tune it up to 38 degrees total. The if I ran lower octane at that high a timing I get pinging every time, and I worry about motor damage.
 
so are you able to run as much advance as you want as long as it doesnt ping? because since i've disconnected my vacuum advance and brought the total down to 42 it doesn't blow nearly as much smoke, and it doesn't stumble at all when i mash the pedal, but the performance isn't as great as it is when the vacuum advance is hooked up with the total being at the 54, but then i have the slight stumble, and the weird smelling smoke.
 
dartkory said:
so are you able to run as much advance as you want as long as it doesnt ping? because since i've disconnected my vacuum advance and brought the total down to 42 it doesn't blow nearly as much smoke, and it doesn't stumble at all when i mash the pedal, but the performance isn't as great as it is when the vacuum advance is hooked up with the total being at the 54, but then i have the slight stumble, and the weird smelling smoke.
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Yes and no. Virtually everyone who times their car by ear will have it too far advanced. That's because the car seems to run better and with more power. However, you have to remember that every spark is a mini explosion. You want the piston in the optimal position when that happens. Otherwise, as Bad440 wisely stated ... "there could be a cutting torch at work in your cylinders". Higher octane fuel allows more advance before pinging. If you like the power with your high advance, try some expensive race gas. I have to mix mine no matter what with my compression, but if I want 38 degrees and full power, I have to run full race gas, and that costs a fortune. All that being said, 42 is too high. I don't care how much power you have or any of the fun stuff you are getting, 42 is too much. There are threads and many good guys on FABO who can talk about your vacuum advance and whether you need it or not, but no matter what you end up with, your max total timing should be mid 30's. MAX. And with your compression, possibly even high 20's. I am 11.8:1 and I max out my timing at 38 degrees and run full 110 octane at that timing.
 
Mopar to ya said:
You are running rich. You see a lot of souped up cars that smoke when you get on it. Getting the carb in tune is a never ending process sometimes. My Holley is causing the same problem. It is the carb the engine was dyno'd on and I am sure they tuned it for maximum power, but that has little to do with every day driving. I turned the mixture screws in 4 turns and still run rich. I have to check the jets and I am sure the venturis are too big. As for me, I will live with it because I plan more changes this winter and that carb is going away.

Question: with your timing at 42 degrees, which seems high to me, are you getting pinging or knocking? Are you running pump gas or racing fuel?
Click to expand...



what?you turned the idle mixture screws in 4 turns?how far out are they?
 
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