smoke blows out of the valve cover

[b4black]

You've looked inside and seen the NA pistons first hand? How did you ID that they are NA?

Please bear with me in my dogged determination.

Of course I haven't seen the pistons. The motors run fine. The junk yard motor still has the NA valve covers on it (which makes changing the oil difficult). The reman motor is just that - a 1990 reman from a place that does all kinds of motors. I'm confident it's not a turbo motor inside.

 

[jiho2]

No no no no no. Look at the tops of your pistons. If it was ignition, the tops of your pistons would be broken. They aren't. Instead, it's the sides that are cracked, way down on the skirts. That means that what sounded like "knock" was actually piston slap under boost pressure. Caused by the pistons being too cold and not expanding enough.

The knock sensor system is always operating. You don't need to be in closed loop for that to work for you. It was there before these motors had a computer and closed/open loop at all. And you wouldn't expect knock in open loop anyway. You get knock when things are too hot, not too cold. That's a very murky theory.

 

[jiho2]

Of course I haven't seen the pistons. The motors run fine. The junk yard motor still has the NA valve covers on it (which makes changing the oil difficult). The reman motor is just that - a 1990 reman from a place that does all kinds of motors. I'm confident it's not a turbo motor inside.

I'll have to let you go then.

Anyway, I'm starting to agree that later NA pistons (by '83, anyway) would be fine for a Carb Turbo conversion. The crowns in particular are identical to any Turbo crown, and they use the same rings.

A Hot Air conversion would be dicier. I've seen a few too many pics of broken Hot Air crowns (Turbo pistons, mind you) caused by flaky MAF sensors and cam sensors, among other issues. The Carb Turbo setup is far more stable and reliable.

Don't even talk to me about an Intercooled conversion.