65 tail smoke

[Jimmy Roggenbuck]

I have just joined the NCRS and have just bought a 65 roadster 327/350. I just started to notice the warming up white exhaust but after the car gets warmed up it continues to smoke out the left exhaust and not the right I am going to have someone check it thought I would try to get some opinions here first. The engine was rebuilt but do not know when/who?
Thank you for your help and support this is a great help for me.

[Ed Jennings]

Re: 65 tail smoke

Check to se if the heat riser in the right exhaust is present/functional.

[Joe C.]

Re: 65 tail smoke

Jimmy:

Give us more information.

What color is the smoke?
Do you think it is water vapor (God forbid)?
Does the tailpipe drip water drops?
Does the exhaust have an odor of fuel?
Pull all the plugs, keep them in order, and describe how they look.
How does the car run? Any dead cylinders?

Hopefully it is the heat riser, as Ed suggested. It could also be the baffle in the center exhaust crossover in the intake manifold. Your engine should have NO baffle installed. It could also be a fuel distribution/mixture problem caused by a dirty or incorrectly adjusted carburetor.
Keep us posted.

Joe

[Jimmy Roggenbuck]

Re: 65 tail smoke

The smoke is a white smoke like when you first start the only thing is that the right side does not stop. The vapor is dry and there seems to be no water in the tailpipe. I have found that my heater core has a small leak and will soon be replaced. The plugs I just changed and showed to have more of a carbon build up on the right than the left. I have just purchaced the car and not sure on the carburator it is a holley with (list 4778 under it is 2984)a clean appearance inside it. The car runs great and is very smooth at idle and when running just a little concerned. How do you check the heat riser? On passenger side? Friend suggested it could be the valve seals.

[Jack H.]

Re: 65 tail smoke

Heat Riser: With engine cold can you move the counterweight up & down, albeit against internal resistance? As engine reaches operating temp, does the valve open on its own accord (functional bi-metal coil; counterweight changes position)?

How many miles on car since engine rebuild and over what period of time? If still in the wear-in phase (less than 5K miles), what oil is in the sump? If some genius put something like Mobile One synthetic in the crank, you may NOT be getting rings to properly seat to piston walls....

Of interest is the comment your RH bank of plugs appeared carboned vs. LH bank looking good/normal. Plugs tell the whole story of what's going on! A compression test followed by trickle down test will tell you what/when/where about cylinder integrity (compression tells you gross functionality and trickle down/leak down tells you who's at fault--piston ring, intake valve, exhaust valve). So, no need to guess, you can test and determine....

[Jimmy Roggenbuck]

Re: 65 tail smoke ammended

I miss quoted myself the carbon build up is on the left where the smoke continues after warm up. I have found that I do not have a heat riser just what looks to be a giant spacer with no counter weight or valve. I am trying to do some research on the rebuild but assuming it was not to long ago since all the manifold and exhaust bold moved with little effort. I will change the oil to good ol' 10w-40 and change the filter. My one question is that one side is burning cleaner on the plugs and the same side is smoking and both use the same oil and gas so why the difference. To me it wolud make sense that the valve seals would be a larger contributer on the drivers side. Hope to have the new heater core in and running to take it to have the whole engine checked out. should the heat riser be added before I go?

[Jack H.]

Re: 65 tail smoke ammended

Heat riser valve is pretty much a 'cosmetic' item with today's typical classic Corvette. Few of us drive 'em in the winter months when the function (force a restriction and pump warm air up to the carb choke to speed up pull-off action) is important.... I wouldn't worry too much about lack of heat riser UNLESS you want to show the car and not lose points for the absense of a factory component and/or pass a Performance Verification test.

There are a number of things that could explain oil consumption and plug fouling on the LH bank and not the RH. Gotta tell you FEW of the possibilities are good....

The best way to proceed from here is to apply science. Get the car to a competent mechanic and have a full compression test followed by a leak down or trickle test. The first will give you cylinder by cylinder the numbers of what your gross compression is. The mechanic will explain what's good/bad, but basically you want each 'hole' to have high compression AND you want the readings to be consistent (within 10 psi or so) all the way around.

If/when individual cylinders are found to have low compression, that's were the leak-down test comes in. It will identify whether the cause is piston ring, intake or exhaust valve seal....