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Re: Smoke!! Help! (6/16)
 11/14/20 5:12am
Bluesting 70
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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?

Re: Smoke!! Help! (7/16)
 11/14/20 10:30am
Adams' AppleLifetime Member
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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....



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Re: Smoke!! Help! (8/16)
 11/14/20 11:43am
73shark
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Overland Park, KS - USA

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Bluesting 70 said:

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?



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



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Re: Smoke!! Help! (9/16)
 11/14/20 2:27pm
Bluesting 70
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73shark said:
Bluesting 70 said:

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?



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


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. 

Re: Smoke!! Help! (10/16)
 11/14/20 5:51pm
Bluesting 70
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One other thing o meant to mention, it’s dieseling pretty bad at cut off. It’s done that before but much more now. 

Re: Smoke!! Help! (11/16)
 11/14/20 10:11pm
73shark
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Overland Park, KS - USA

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1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.


Joined: 7/9/2003
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Bluesting 70 said:

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.



|UPDATED|11/14/2020 8:11:08 PM (AZT)|/UPDATED|


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Re: Smoke!! Help! (12/16)
 11/15/20 1:47pm
manchestersharkLifetime Member
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Check timing for dieseling.

Re: Smoke!! Help! (13/16)
 11/15/20 2:35pm
Bluesting 70
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73shark said:
Bluesting 70 said:

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.






Re: Smoke!! Help! (14/16)
 11/15/20 2:36pm
Bluesting 70
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manchestershark said:

Check timing for dieseling.



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. 

Re: Smoke!! Help! (15/16)
 11/15/20 2:43pm
Bluesting 70
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73shark said:
Bluesting 70 said:

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.




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. 

Re: Smoke!! Help! (16/16)
 11/23/20 11:37pm
73shark
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Overland Park, KS - USA

Vette(s):
1973 Orange Metallic Coupe (orig owner), L82, 4 spd (WR), PS, (A/C & PW (I installed from wrecked 73)), leather, AM/FM Stereo, ran with '65 FI unit earlier & will again some day.


Joined: 7/9/2003
Posts: 642

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.



|UPDATED|11/23/2020 9:37:47 PM (AZT)|/UPDATED|


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