Knock only at 4000 RPM even after reducing timing

[Fast4.7]

...and only fit down to LS1's 3.91 bore, will not fit the smaller 5.3.

They will fit a 5.3 with a bore notch. Factory rectangle port LY6 head will too for that matter. Not afraid of a bore notch either. GM did them factory on the 396/402s and the 366 truck engines. I have run the dog snot out of a 366 school bus engine with a blower too. 366 and 427 truck engines use the same heads so the 366s 3.935" bore had to be notched to clear the small valve 427 truck heads and the 366 had domed pistons to keep some compression. My buddy David Kauffung put 2.00" valve Fast Burns on a 305 with a bore notch and made 468 hp using 0.600" lift.

[blindsquirrel]

We all get to make our own decisions about what compromises we're willing to tolerate. The 396/402 had a notched head gasket to get rid of the overhang/crevice volume. Nothing like that exists for a 3.78 bore LS. And if the 5.3 were an iron block it wouldn't be quite as concerning, but on an AL block, and with boost? The very top of the sleeve is the last place I want to make it thinner than it already is.

There's all kinds of half-assed shit people do and get away with and say is just fine and everyone is worrying about nothing. Not everyone is the same about that stuff.

[Fast4.7]

We all get to make our own decisions about what compromises we're willing to tolerate. The 396/402 had a notched head gasket to get rid of the overhang/crevice volume. Nothing like that exists for a 3.78 bore LS. And if the 5.3 were an iron block it wouldn't be quite as concerning, but on an AL block, and with boost? The very top of the sleeve is the last place I want to make it thinner than it already is.

There's all kinds of half-assed shit people do and get away with and say is just fine and everyone is worrying about nothing. Not everyone is the same about that stuff.

Head gasket matches the chamber, not the block. A 5.3 gasket would overhang the whole chamber. I was also speaking more iorn block anyway.

Perfect example of the head gasket matching the head. My 4.030" bore SBC has a 4.166 bore gasket because it matches the cylinder head where a 4.060 would hang into the chambers unless it was an oddball D shape.

[blindsquirrel]

But all LS head gaskets are fully round. BBC stuff is the shape of the chamber, which ends up matching the shape of the top of the cylinder when the small bore motors get the notches. Lots of SBC gaskets are an oddball D shape.

Thousands of people have put 4.100" LS9 gaskets on 5.3s. Is that proof that overhang and the crevice volume it creates is not a thing that anyone should be concerned about? I'd rather do things better than that, and if the right parts aren't available to do it right then sometimes that means that a project just stops happening.

[brycedrue]

Are you sure there are no knock sensor codes present on this one? Are any knock sensor codes "turned off"

This looks how they behave when it has a knock sensor code pending or present. I didn't see one in the log.

Alvin, I think you just helped me. I checked and found that knock sensor 1 was disabled, I enabled it like the stock tune file. Turned all knock sensor settings back to stock and made the same pull under same conditions and it didn't log any knock. I was running only 7 degrees when knocked showed and now back up to 13 degrees with no retard logged. Thank you!

[Alvin]

Awesome.. Good to hear!