Cleaning carbon off the intake valves

Stevehose

Stevehose

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I’m not much on miracle additives but I’m pretty impressed with this. The local bmwcca rep recommended I try some Lucas Deep Clean fuel system cleaner 10512. Here are the results after 3 bottles and 3 tanks of gas:

Before:

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After 2 bottles:

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After the 3rd:

IMG_5509.jpeg


Almost 100% clean.

No affiliation, but will be using every couple of tank fills.
 
stphers said:
Very nice but Steve, you drive your car, that makes a big difference as well

Thanks, Rick
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Yes, but that buildup was from only 750 miles of driving on a new engine and I have been fighting carbon for a long time now due to the webers liberally spraying fuel at each push of the pedal and idling at 12.3 afr.
 
I use the Lucas oil additive in my F250 PSD with good effect (so far). I put a quart in with every other change (in place of a quart of oil - the crank holds 15 quarts, so 1/15 dilution rate).

Thanks for the info. Will keep this in mind if I get into any carbon deposit issues with my gasoline fueled cars.
 
Stevehose said:
Yes, but that buildup was from only 750 miles of driving on a new engine and I have been fighting carbon for a long time now due to the webers liberally spraying fuel at each push of the pedal and idling at 12.3 afr.
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Maybe you need to adjust your acceleration pump ?

Breiti
 
I thought carbon build up on the intake valve was usually caused by oil vapor from the PCV system. From what I understand it is most common with direct fuel injection engines. Carbureted or throttle body injected engines normally don't have a serious problem with carbon build up on the intake valve because the gasoline in the intake fuel/air mixture helps to clean the valves, especially with a good detergent additive in the gas.

I have been running Webers since the early 80s and have not experienced a serious issue with carbon build up on the intake valves. I wonder if it is something else that is causing the carbon build up.
 
gwittman said:
I thought carbon build up on the intake valve was usually caused by oil vapor from the PCV system. From what I understand it is most common with direct fuel injection engines. Carbureted or throttle body injected engines normally don't have a serious problem with carbon build up on the intake valve because the gasoline in the intake fuel/air mixture helps to clean the valves, especially with a good detergent additive in the gas.

I have been running Webers since the early 80s and have not experienced a serious issue with carbon build up on the intake valves. I wonder if it is something else that is causing the carbon build up.
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I have no PCV system so that's not an issue. I thought direct injection fouls valves because it sprays the back of the valve and has an incomplete burn. You've been running sidedrafts and not had this issue?
 
I do not have side draft Webers on my Coupe. Mine are the JAM Engineering kit which is down draft and does have the oil vapors from the crankcase feed back into the air breather as is stock.

I know of new cars that had direct fuel injection that were having problems with carbon build up on the intake valves. The way they solved it or slowed the buildup was to have both direct fuel injection and throttle body injection. Does your engine just vent to atmosphere? I guess with side draft carbs you may not have the oil vapors going back into the intake.

A proper direct injection system should not have incomplete burn, or it would not pass emissions.
 
I run side draft carbs on my Austin Healy Sprite race car. I thought side drafts were an advantage due to better air flow by having a straight shot into the heads with minimal corners to slow it. Yes, more gas gets in there but so does more air. The air fuel ratio should still be the same if the carbs are set up properly. Maybe you are running too rich, or the accelerator pump is pumping too much as has been suggested before.

I do get some carbon build up on the intake valves of my race car, but I always considered that is from oil that gets past the guides and seals for lubrication. The buildup is more on the stem than the radius and flat area. I run worn out seals on my exhaust valves for better lubrication. The heat from the exhaust does a good job of burning that off. The high lead content of the 112 octane race fuel leaves some build up.
 
I'm hoping that now that my valve cover breather has the correct diameter hose, that any carbon caused by oil burning as you mentioned will also go away. I'm monitorung the valves and the 123 distributor for further indiscretions. Also, I have my AFR's in range now - plugs are looking good.
 
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Saw an interesting segment on Valvoline Restore oil if you want to get clean from both sides. Not sure if this is an infomercial or not? Lake Speed Jr is the guy talking.
 
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