Hi Rollsman4!
To diagnose your "Check Engine" light yourself, if you don't have a scanner it is pretty easy.
1: Pull your ashtray out. Under there is the ALDL connector.
2: With the engine off/key on. Jumper a wire from terminal "D" to "E". Your check engine light will begin to flash.
3: Count the flashes. 1st sequence should be: 1 flash-pause-2 flashes. This will repeat this code 2 more times. = Code 12
Then it will flash in sequence (3 times) the trouble code that is stored.
Example: 3 flashes-pause- 4 flashes, then it will repeat this 2 more times. = Code 34
If there is more than 1 code stored it will go on to next code.
If you get a code or multiple code #'s, let us know what they are (if you don't have a chart) and we can tell you what the problem may be.
Valve covers. The correct ones are made of magnesium and have a black finish. There are aluminum repro's that you can make look like the originals. Or you can keep an eye out on Ebay for a set off of an '81-'82 vette.
Hope this helps!
Sarge

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GEN III 5.7L "LS6" Engine swap
TKO500 5 spd.
3.54 Dana 44