Carbon problem

[jeff l]

I have a 8 month old rebuild that is 10 to 1 350, I run a 600 e-brock carb.

I am finding a lot of carbon on the plugs, so I put in a good napa set of wires and bought a hotter 45 ac delco plugs, I need to return the plugs b/c they were to long w/headers.

So my question is do they make a shorter hotter plug, and by doing this will it help the carbon problem.

Thanks for any help---Jeff

 

[Hogback Fabrication]

Your carb is probably running too rich.

 

[jeff l]

Your carb is probably running too rich.

is that something I can do or should I bring it to a shop?

 

[Hogback Fabrication]

Changing jets is easy to do. I actually don't have much experience with Edelbrock carbs so I can't tell you exactly how to do it but I bet Edelbrock's website has instructions.

Do you ever see black smoke coming from the exhaust? You want smaller jets, probably 1 or 2 sizes smaller. Try 1 size smaller and recheck the plugs. You want a light tan color on the ceramic part of the plug. White is lean, brown or black is rich.

 

[jeff l]

No black smoke, just a lot of carbon.

 

[Hogback Fabrication]

No black smoke, just a lot of carbon.

Then you probably only need to go down 1 or 2 jet sizes.

Black smoke means its running really rich which would require a more drastic change.

 

[vortec]

save all that carbon up and find superman to press it into diamonds. it worked in the movie when he stole that chunk of coal from the miners.

if you mash the gas, does it bog? can you smell fuel when you're driving? is the idle rough? all of those things can indicate a rich condition. my carb is a q-jet, and they have 2 screws on the front to adjust the idle mix. i need to mess with mine. idles like crap. does yours have an idle mix adjustment? with your high compression ratio, rich is much safer than lean, as far as engine damage is concerned. the compression itself may be your problem. have you tried messing with the plug gap? a higher compression engine will quench the spark easier, so running a narrower gap may be required.

 

[jeff l]

save all that carbon up and find superman to press it into diamonds. it worked in the movie when he stole that chunk of coal from the miners.

if you mash the gas, does it bog? can you smell fuel when you're driving? is the idle rough? all of those things can indicate a rich condition. my carb is a q-jet, and they have 2 screws on the front to adjust the idle mix. i need to mess with mine. idles like crap. does yours have an idle mix adjustment? with your high compression ratio, rich is much safer than lean, as far as engine damage is concerned. the compression itself may be your problem. have you tried messing with the plug gap? a higher compression engine will quench the spark easier, so running a narrower gap may be required.

Yes, sometimes, idles fine. its more like I have to ease the pedel to prevent it from "bucking" or bog and I have a lot of carbon on the plugs. I feel like the spark is not hot enough. what gap should I set my plugs?

 

[jeff l]

also it seems like this motor should handle any amount of gas thats put in, inless the air mixture is not right, I dont know

 

[vortec]

also it seems like this motor should handle any amount of gas thats put in, inless the air mixture is not right, I dont know

it has a limit, like any other motor. 600 cfm isn't huge airflow, but i think that should be sufficient unless it was jetted for something much closer to sea level, was previously used on an engine with forced induction or something.

i can't say what plug gap for sure. how big are they set right now? if you have them at .045, maybe try .035 or something and see how it works. btw, quenching can appear like plugs that aren't hot enough because if the spark is getting snuffed out, it can't burn off oil, gas or anything else that gets on it.

and, to go back to a rich carb, rich mixes cool an engine, so that's a little deceptive, too.

 

[Hogback Fabrication]

Your motor can't just handle any amount of fuel that's thrown at it. Sure, it might make good power. And that means its going to draw in plenty of air and fuel. But it needs both in the right ratio.

The ideal air/fuel ratio is 14.7:1. If you are running richer than that (have too much fuel, bringing the ratio below 14.7) you can foul plugs or wash out piston rings (gasoline is a very poor lubricant). If you are running too lean, the engine will produce tons of heat and you may have detonation problems.

 

[jeff l]

it has a limit, like any other motor. 600 cfm isn't huge airflow, but i think that should be sufficient unless it was jetted for something much closer to sea level, was previously used on an engine with forced induction or something.

i can't say what plug gap for sure. how big are they set right now? if you have them at .045, maybe try .035 or something and see how it works. btw, quenching can appear like plugs that aren't hot enough because if the spark is getting snuffed out, it can't burn off oil, gas or anything else that gets on it.

and, to go back to a rich carb, rich mixes cool an engine, so that's a little deceptive, too.[/quot


Gap is at 35, and some people are tellig me to make it bigger for a bigger spark

 

[jeff l]

Your motor can't just handle any amount of fuel that's thrown at it. Sure, it might make good power. And that means its going to draw in plenty of air and fuel. But it needs both in the right ratio.

The ideal air/fuel ratio is 14.7:1. If you are running richer than that (have too much fuel, bringing the ratio below 14.7) you can foul plugs or wash out piston rings (gasoline is a very poor lubricant). If you are running too lean, the engine will produce tons of heat and you may have detonation problems.

My motor has very low power, and I dont know what the ratio is I had the carb tuned 8 months ago ,and when I thought it was running rich I turned both screws infront 3/4 turn down. I really cant tell a difference but it does sound like it has a better lope.

 

[Hogback Fabrication]

The screws you turned affect the idle and nothing else.


I still don't think its tuned right.