Exhaust Tube

[ranger372]

While I had the left exhaust manifold off to replace the Cylinder Head Temp. Probe. I noticed the exhaust tube for Cylinder #4 had a white chalky coating. What ILL is this telling me?
Thanks, Steve D.

[61SuperMonza]

The exhaust tube may have VHT applied to it. Odd that only one tube was coated. Just a thought. Do you have a picture?

[ranger372]

Here is a photo, exhaust tube 6 looks good. It is exhaust tube 4, I'm concerned about.

[bbodie52]

Perhaps number 4 is running lean for some reason. Is the compression reading on that cylinder significantly different from the others, or does the number 4 spark plug look significantly different from the others? Is there any sign of the steel port tube being loose in the aluminum head? Perhaps an air leak into the exhaust flow could affect the color of the port deposits.

[61SuperMonza]

I didn't realize you meant the inside of the exhaust tube. Yes it's running lean. Interesting that you do have VHT on the pushrod tubes. I did the same thing on my engine.

[61SuperMonza]

From the look of the engine it has been well cared for. So that narrows things down a bit. I would think it is unlikely to be a carburation issue. I would think #4 would run rich if anything. I'm thinking a possible ignition issue.
What type of ignition system are you running as well as plugs? Did you build the engine? All the info we can get helps.

[ranger372]

Car is a '65 Corsa conv't. 180 Turbo. Engine rebuild by myself (1st timer, 69 yr's). Ignition is points, Plugs - I will have to look - Tuesday afternoon. Will try to check and compare compression between cyinders also.
Turbo rebuilt by - Steve Goodman, Weber carb. rebuilt by - Ray Sedman.
Car now has the dash disassembled for replacement of all dash gauges, so unable to test drive.
Only perhaps 150 miles have been put on the car since rebuild. Exhaust would sometimes spew white smoke from the exhaust pipe upon starting, would stop shortly after.
Thank You,
Steve D.

[Wagon Master]

Does #2 look like #6 or #4?

[ranger372]

2 has a slight amount of white. I have not removed the the right tins or manifold off as of yet. I do not know what 1,3 and 5 look like. Think I want to check Compression first. Will check on Thursday.
Plugs are NGK #B6H gapped @ .035, just pulled #4 cylinder, appearance looks good - dark gray
Thanks,
Steve D.