Coal Rolling LBC Style

[SaxMan]

I took Baby Blue out for a run tonight with my daughter. When the motor got to around 3,000 rpms, I was putting out HUGE clouds of bluish smoke that would linger while I watched it recede in my mirror. It was almost embarrassing how much smoke was pouring out of the tailpipe. I felt like one of those big diesel pickups rolling coal. I kind of wish I bumped into one of them just to smoke 'em out.

Two things changed on the car: First thing is that I decided to try one of those "open" type air cleaners. It was more for cosmetics than practicality as I thought it would look nicer than the beat up stock air cleaner back It does look nicer, although I could see it being a bigger nuisance to take off and reinstall.

The second thing that changed was the temperature. Last week, I tuned the carbs so that the mixture was just a bit on the rich side for a 90 degree day. On tonight's ride the temperature was only around 70, and likely below that in the hollows. I'm wondering if my mixture was overly rich for the conditions. When I first started the car with full choke, it was idling roughly and even stalled before the motor finally warmed up.

I suppose I could slap the stock air cleaner back on, or try leaning out the mixture to rule out which one is the factor, or wait for the temperatures to get back up around 90 again and see if that changes the result.

 

[Billm]

Blue smoke is generally not fuel (rich mixture) but oil- did you perhaps disable the PCV system when you put on the new air cleaner?
BillM

 

[SaxMan]

I checked the PCV and the oil breather. The PCV valve was previously disabled and it is plugged off, which apparently is a "typical" modification to this particular year of the Sprite ('69). I still have the oil breather on the front of the engine going into a "Y" pipe to connect both carbs. I'm thinking that maybe the lack of resistance with the more open air cleaner is causing some kind of imbalance and not allowing the oil to be sucked out? If I shift short and keep the revs below 3000 rpm, no smoke. The smoke is heaviest when under moderate to hard acceleration in 1st and 2nd gears at and above 3000 rpms. It just doesn't seem to make sense that a change in air cleaners would result in this big of a shift in the car's behavior. Until today, the car had been running better than at any other time since I've owned the car.

 

[Billm]

That "Y" pipe IS the PCV system- that sounds good. You may check that the pipes at the "Y" are not clogged up
BillM

 

[LarryK]

Might need summer oil. 10w/40 or 20w/50 do not know what you are using. Over rich would be black, blue is oil. Might also check oil return holes in back of head.

 

[nomad]

Did you fit an air cleaner with a oiled element???

Kurt

 

[SaxMan]

I run 20/50 year round. Element is a reusable foam element. I'll go back to the stock air cleaner. If that quiets the smoking down, then I'll start poking through the PCV system and try again.

 

[LarryK]

What carb? SU to full?

 

[SaxMan]

I believe they are HS2s, but I'm not at home to look it up.

 

[nomad]

I run 20/50 year round. Element is a reusable foam element. I'll go back to the stock air cleaner. If that quiets the smoking down, then I'll start poking through the PCV system and try again.

The reason I ask is that if you oil the foam element as you are supposed to, you will suck oil out of the air cleaner for a while and, of course, get blue smoke. Perhaps that was the problem???

Kurt.

 

[SaxMan]

I put the stock air cleaner back on. After I blew out the residual oil within the first 2 or 3 miles, the car magically stopped smoking. I've learned my lesson many times about trying to fix things that aren't broken, so, at least for now, the stock air cleaner stays on. However, my curiosity is killing me on why this happened.

I just put the air cleaner on the car straight out of the box, no oil on the element, and I don't think it came from VB pre-oiled. I went with the el cheapo one just for this reason...in case it didn't work. I figured if I liked the results, I could always upgrade to a better one. I'm glad I didn't plunk down money for a high end model.

Does the PVC flow from the engine into the carbs or vice versa? Either way, I'm guessing the difference in air pressure between the two setups is causing the oil to enter the intake at excessive amounts. I'm half tempted to try putting an open air cleaner on one carb and the regular air cleaner on the other just to see if it is one or both carbs causing the issue.

Meanwhile, I'll go back to enjoying the driving. I took my daughter out tonight in the car on another beautiful evening. Her smile makes all the tinkering worth it!

 

[SaxMan]

So after the switching back and forth, Baby Blue turned in her best mileage ever since I bought the car: just a tick under 29 mpg, which was consistent with what longbridgehealey was getting when he owned the car (I think he said he would average around 28 mpg). I'm wondering if my mileage was suffering from the PVC being clogged and switching to the open air cleaners cleared the blockage, creating copious amounts of smoke, but allowing the PVC to work as designed again.

 

[nomad]

Glad its working again. If you have the pancake PCV and it was plugged it more than likely would just make for lots of leaking but different restriction on the intake may have made it act up.

Kurt.

 

[SaxMan]

Mine isn't the pancake. It's the oil breather on the front of the motor with a hose going back to the Y-pipe that splits it into the the two carbs. I believe that the car did originally have the pancake PCV, but it was long since removed and plugged over.