355 Looses power around 5000rpm

[thatclappedsilverado]

Put 93 in it today and ran it around and it’s now running fine. Curious why that change would affect it? Not too high of compression.

 

[PlayingWithTBI]

Curious why that change would affect it? Not too high of compression.

If you get KCs and KRs, depending on how much timing it pulled may cause it to flatten out@5000+ RPMs

 

[thatclappedsilverado]

If you get KCs and KRs, depending on how much timing it pulled may cause it to flatten out@5000+ RPMs

Sorry if I’m just stupid but what is kc and kr?

 

[PlayingWithTBI]

what is kc and kr?

Sorry about that - Knock Counts and Knock Reductions, meaning if the computer sees Knock Counts (from the Knock Sensor and ESC module) depending on how many in a certain amount of time, it will reduce timing (KRs) until it doesn't see any more, then depending on decay time in the program, it'll restore timing back to its SA (Spark Advance) tables.

Maybe this EFI Dictionary link will help. Down towards the bottom is another link with acronyms in alphabetical order.

www.gearhead-efi.com/gm-ecm-pcm-conversion/efi-dictionary.html

 

[thatclappedsilverado]

its carb with big cap hei no computer control besides fuel pump which eventually is going to get ran to a stand alone relay when i get the time to go through the wiring