Smoke, Smoke Options

[Boothy]

Cheers all!

Sorry, but I again need to ask for help.

New engine blowing smoke. 1.7 punched out to 2.0 with a big bore kit. Cam, Weber 40s. It started and ran pretty well late last fall. Used engine break-in oil as recommended. No smoke but sluggish acceleration -fine at high RPM.

With the warm weather (finally) I swapped out the Weber jets to the recommended .50, 1.50, and 1.95. Ran it up to 3300 with a timing light. I remembered I did static timing but not dynamic. Now it sounds pretty good but I'm seeing light blue smoke and a really black exhaust. I don't think the jets were that different but no markings so not sure.

My immediate horror was a broken ring -I really don't want to pull the engine again. It idles fine and sounds strong. I'll do a compression check. When it idles, there's no smoke. When I bring it up, it begins to smoke a little. Then it's consistent—no horrible but noticeable.

It sounds strong. It idles nicely at a 1000 and revs up fine. I'm hesitant to push it until I figure out what's going on. Changed the oil to 20W-50. Could it be, with the soot on the tailpipe, my jets are wrong? Stretch I know but hopeful. Heads are new so the oil in the guides shouldn't be an issue.

As always, thanks in advance!

[bdstone914]

Oil smoke? Black run rich smoke? I would start with a compression test after a valve adjustment.

[VaccaRabite]

Possible issues:
Rings have not yet seated.
Overfilled with oil.
Running way too rich after carb adjustment.
Timing is off.
Broken Ring
Broken piston.
Some combination of the above.

to do (in this order, starting with a DEAD cold engine. Like it has not run since the previous day cold.

1) adjust valves.
2) check your oil level.
3) Warm up engine. Drive car. Fixed? WOOO! If not, continue below.
3.5) adjust your timing. You need to set static timing AND total advance. You can't just set one and ignore the other. Pull your plugs out while you are up there. Take pictures of each plug end, and not what cylinder each plug came out of. Static timing alone isn't enough. Running too advanced is bad.

4) compression test (plugs out, throttle open, engine warm.) Post results. You are looking for a cylinder with a significantly different reading then the others. Compression on a newish engin3 should be above 130PSI each, and all cylinders should be within 5% of each other.
5) While the engine is warm and the plugs are out, do a leakdown test. This will tell you what percentage leak you have, and where it is leaking. Bubbles at the cylinder base mean your case is warped. Bubbles at the top is a cylinder leak. Bubbles at the valve is a bad seat. And air coming out of the oil tower indicates bad rings. Shit leak values on all cylinders means rings aren't seated yet. Shit leak values on 1 cylinder means the engine needs to come out.

Hopefully it was just overfilled with oil. But at the end of this testing you should have a very good idea of what your issue is.

Zach

[Boothy]

Thank you for the detail! Will do all in order.

I'll add that I'm running the 123 Distributor.

[Eric_Shea]

Compression test first. If everything is good then...

100 miles to break in bearings (assuming you've already broken in the cam properly).
500 miles loaded to break in the rings.

[Nogoodwithusernames]

My rebuild stock-ish 1.7 was breaking in and running well, but then for a couple days one set of ring gaps lined up even though I spaced them properly at assembly and it burned oil in one cylinder. It resolved itself with some continued break in miles. White smoke so I knew it was oil.

[Boothy]

An update...

Thank you all for the advice.

It's been a while due to other demands but I adjusted the valves again and carefully checked the timing. I even added the fancy CB Perf valve covers to stop the oil drip on the driver's side -no go. After $200+ dollars and some wrestling, IT STILL DRIPS. Everything was clean. I'm ready to use roofing tar.

Anyway, sitting with a beer, looking at her lovely stern and digging deep down into my soul, I had an epiphany. Both sides of the exhaust are black as Hell, but it idles just fine after warming up. Hmm. "You re-jetted you dickhead so it's too rich."Never thought that would cause smoke, but I'm hoping that's the culprit. If it were a ring or something, it would only be on one side etc.

I re-jetted to 1.95, 0.50, and 1.50. Sorry just the bags in front of me.

I have a 1.7 punched out to 2.0. Weber 40s. I re-did the venturi to whatever was recommended.

Correct jetting?

Thanks in advance!

[emerygt350]

I found my driver's side is a pain too. I use a regular gasket with a little coating of the high temp gasket maker I can't remember the name of on all surfaces. It holds the gasket in place too. I tried the thick gasket but no go leaked awful (tried that twice). Make sure you watch that cover as you slip the clip on, mine really likes to move.

Thought about bringing it to a dyno and jetting it professionally? Do you have an afr gauge?

A vacuum gauge can tell you all about what is going on in your engine as well.

https://m.roadkillcustoms.com/diagnose-comm...s-vacuum-gauge/

[Boothy]

Thank you! I'll try the gasket maker. I, too, tried the thick cork, but no go.

I swapped back to the old mains (136?) at lunch, but no improvement -unless there's so much to burn off. I doubt I'm that lucky.

Right. Ordered a gauge online for the compression test. That will give some light.

This has been such a long process I'm really tired of it but trying to maintain a positive outlook. The thought of dropping the engine again is up there with a dental visit. (IMG:style_emoticons/default/smile.gif)

I found my driver's side is a pain too. I use a regular gasket with a little coating of the high temp gasket maker I can't remember the name of, on all surfaces. It holds the gasket in place too. I tried the thick gasket but no go leaked awful (tried that twice). Make sure you watch that cover as you slip the clip on, mine really likes to move.

Thought about bringing it to a dyno and jetting it professionally? Do you have an afr gauge?

A vacuum gauge can tell you all about what is going on in your engine as well.

https://m.roadkillcustoms.com/diagnose-comm...s-vacuum-gauge/

[TheCabinetmaker]

What is 1.7 "punched out to 2L"?

[Boothy]

What is 1.7 "punched out to 2L"?

The big bore kit from AA. Hoping I didn't get dog shit rings. Compression test soon will tell.

I used the good break-in oil. Did the rev at whatever to seat the rings. It was fine for a long time. Now smoking. IDK.

People wonder why I drink.

[emerygt350]

I have the 96mm pistons/sleeves from AA. They have been very good for me
I only did the top end and did not use any kind of break in anything. Just mobil1 euro 0w40 and drove it. Was racing it in 300 miles. 4k since the rebuild. This was starting with a GA 2.0 though.

[brant]

How many miles on the engine since the build?