I’ve had the car for 12 years and all along I’ve had a subtle smoke at idle and a little burn of the eyes. I rarely drive it but when I do it rides just fine. With corona keeping me home now, I’ve started doing some things to it I always wanted to do one being clearing up this smoke. Started with a tube up. Rebuilt the msd dizzy, new plugs, wires, msd coil, brand new edelbrock 650 carb, air filter, fuel filter and after struggling a little getting the timing right, the smoke is a lot more evident. I did a compressions check and all came back 200 to 205. Did a combustion leak test and twice and the liquid stayed blue. I’m running out of things to check on. I would greatly appreciate any ideas. 

Does it smoke all the time?

Is it blueish or white smoke? More input please....😉

Joel Adams
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Before it did not smoke all the time but since I did all the work it does it all the time. It’s white smoke I believe. Does not smell or taste sweet. The oil smells like fuel a little but I have replaced the carb since that started. I’m getting desperate and may change the oil again to see if that helps. 

White smoke could be coolant.

Blue smoke would be oil and since your compression and leakdown are good,  I suspect the valve guides or valve seals are bad. Valve seals are relativly easy to replace. You'll need a spring compressor and an air compressor with a fitting to screw into the spark plug hole to prevent the valve from dropping down after you remove the keepers.

Valve guides are a different story as they require head removal.  Options are knurling or pressing in new guides. I never felt knurling was a long term fix. 

1973 L-82 4 spd

I don’t it’s coolant because it passed two combustion leak tests. 73Shark, is there a way to test to see if it’s valve seals or guides?

A combustion leak test only tests for combustion by-products leaking into the coolant...it wouldn't necessarily show if coolant was getting into the combustion chamber. A crack in the head in certain locations could put coolant into the exhaust stream and not into the combustion chamber, so that could be a possibility.

If it smokes all the time, then you have either oil, or coolant leaking into the exhaust, either from combustion blow-by, a bad head gasket, cracked head, etc.

Valve guides, or valve seal leaks typically leak the worst under a vacuum, such as when you get OFF of the throttle, and the vacuum in the intake manifold is high. This would not be a continuous smoke producer....the smoke would come and go as the vacuum changes. Valve seal/worn guides will also normally show up on a hot re-start, and on cold starts after the engine has been off for some time, but the smoke will dissipate shortly after that....the smoke doesn't stay continuous.

What you COULD have is an intake gasket leak, that sucks engine oil into the intake port(s) while running. That could cause a smoking all the time situation. Hard to test for that, since the leak is on the underside of the manifold. Something to consider....

Joel Adams
C3VR Lifetime Member #56    
My Link


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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

Not that I'm aware of.  Are you seeing any increase in oil consumption?

1973 L-82 4 spd

I’m not. But then again, I haven’t been driving it much at all. I’m planning on pulling the block out soon for bay clean up and paint as well as a few other things.

I appreciate the feedback from all of you. Any suggestions on what I should di while the block is out?  I was considering upgrading the heads. 

One other thing o meant to mention, it’s dieseling pretty bad at cut off. It’s done that before but much more now. 

Since you apparently have a 1970 and if it's not an LT-1, then I assume it still has the original Quadrajet carburetor. Dieseling can be caused by the idle stop solenoid not adjusted right or malfunctioning.
When the engine is shut off, the solenoid denergizes and allows the throttle to completely closed. That shuts off any air to the engine and prevents dieseling.

Edit: I saw in your first post that you do not have the stock carburetor. I don't know if the Edelbrock carburetor utilizes an idle stop solenoid. Other things that can cause dieseling are carbon buildup in the combustion chamber and/or the incorrect heat spark plugs.

If the engine is a small block, you could upgrade with stock LT-1 high-cmpression heads and large intakes. Then you could add the 11:1 pistons.  When I rebuilt mine, I kept the original L-82 heads and put in the 11:1 pistons because I did an .030" over bore.

1973 L-82 4 spd

Check timing for dieseling.

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Good point in the timing. I didn’t build the engine so I don’t know what timing it should be but I run it at 12-14 idle and 30-32 total. I figured that was safe enough. 

Did you get a lot more horse  power off that set up?  I figure I have a good chance to really get it right while I have it out and wouldn’t mind upgrading for a little more power. My vin matches on the block so I’m assuming it’s the original block.  It’s an L46 which came with 11:1 compression.......I believe. 

Haven't fired it up yet.  With my low-compression heads, the 11:1 pistons will give me a CR of 10:1.

Dieseling can be caused by carbon deposits that can get red-hot and will ignite the fuel-air mixture until they cool off.  That's why GM uses an idle stop solenoid that allows the throttle plates to completely close thereby preventing any sir to mix w/ the fuel which prevents dieseling.

Edit: I believe the L-46  (350/350) has the 2.02 intake valves and 11:1 CR.  Probably the two easiest power adders would be a cam and headers.  Of course you could go w/ a blower like a ProCharger but your CR might make that a little dicey.

1973 L-82 4 spd

Well, I decided to get a 383 built from Skip White Performance. I’ll have it in a few weeks. However, I’m keeping the original block on a stand. My son and I will rebuild it as a father and son project. 

How does that compare to a Chevy crate engine? 

1973 L-82 4 spd