Engine rebuild smoking

[Zed Head]

Is there a way to lean it way out?  That might answer the question.  Lean it out until it pops and backfires and dies.  Make a video.

[Patcon]

That looks pretty blue!

[emccallum]

3 minutes ago, Zed Head said:

Is there a way to lean it way out?  That might answer the question.  Lean it out until it pops and backfires and dies.  Make a video.

Thanks, I am past that. I leaned it out until it was starving for fuel with the carb floats and mixture. Zero change in smoke. 

The smoke is even more impressive in person.

[ollie]

Have you done a road test Italian tune up yet?

[Captain Obvious]

6 hours ago, emccallum said:

Its a tough situation. The builder has been a family friend.  I think when I get him back over and he sees it run, he may change his tune. 

Yeah, that's got to be tricky. 

Watched the video. That's pretty blue. And if you've burned up one quart of oil already just idling in the garage, then it's pretty clear there's something internal wrong. From my armchair, it doesn't look like a carb issue.

Curious though... If it is a ring issue, it would seem unlikely that there would be the same issue on all six cylinders. If the rebuilder knew how to do the rings correctly, he might have had one ring slip out of place on one piston or something. But all six seems unlikely unless there was a systemic mistake.

I'm no ring expert, but there are different ring compositions. And don't some of those different compositions take longer to seat than others?

[ollie]

Well that is a lot of oil to chew into just bringing it to life.  Hard to imagine this will self heal unfortunately, and I'd agree with that much oil loss it is lilely to be a ring issue.  

Coolant is all clear from oil contamination?

[Yarb]

@Captain Obviousby chance if the builder used chrome moly rings, Don’t the cylinders have to be honed differently than standard rings. We still don’t have information on what was used on the original rebuild.

[Yarb]

2 minutes ago, Yarb said:

@Captain Obvious By chance if the builder used chrome moly rings, Don’t the cylinders have to be honed differently than standard rings. We still don’t have information on what was used on the original rebuild.

 

[dutchzcarguy]

12 hours ago, emccallum said:

The builder has been a family friend for many years.

THEN.. i would (maybe after some driving to see if the rings settle?) ... take the engine completely apart but at his workshop! Then you can say: i took it apart for you for free .. now you can fix this engine..

12 hours ago, emccallum said:

I think when I get him back over and he sees it run, he may change his tune. 

I would definetely ask him over to see how bad it is!  If he has a firm he does not want you to make negative /bad advertising.

Didn't read it all but if i hear what you did with them you have a good set of carbs. They are not the problem i think.

[jonbill]

I'm sure it'll be obvious once you open it up. Something simple like missing oil rings!

[bartsscooterservice]

On 4/24/2023 at 12:14 AM, emccallum said:

Replaced the valve seals which looked perfectly fine. Adjusted the valves and still have about the same smoke. Spoke with the engine builder. He is very confident in the head and bottom end. He really thinks it is too rich. We talked over several things. I understand where he is coming from. Good compression, all plugs look about the same. I have triple checked the floats, even rigged up a float sync type tube. 

Ztherapy used .100 nozzles and SM needles. I always thought SM needles were for l28 stroker type builds? Anyone else running SM needles with a stock L24.

I had some old carb pistons that probably had stock needles. I swapped them and no difference.

Engine runs strong and adjusting the mixture changes the way it runs, but has zero affect on the smoke. If it was rings, then it would show on compression, right?

Are .100 nozzles stock?

Are SM needles ok with a stock L24?

I have never had a good or bad z smoke this bad! Argghh

 

 

NO, you can't see bad rings on compression readings, the oil can be building a film and still give compression.

 

[HusseinHolland]

I would say you need to do a leak down test. That will clearly indicate where the blow-by is coming from.

The longer you let it idle, the worse it will be, esp if it is or was also running rich & washing the cylinders. Leak down test will remove the doubt.

Edited April 25, 2023 by HusseinHolland