what knock sensor would you use on a 400SBC? or do i have to just totally eliminate that feature and bypass the knock sensor?

 

If you leave a couple degrees room in the calibration, then most any v8 one compatible with your ecm is fine.
Some folks use them as a take it to the edge and run the max timing possible devise, and some just use it to protect things in case of a bad tank of gas.
Other then when the engine makes noises that can't be filtered out, I'd say run it.

 

i want it mostly for the protection aspect... if i get one bad tank of gas on a road trip, id rather have it pull timing and protect the motor then have to get out and adjust the distrib....


now when you go from the 305 to the 350, i was told you HAVE to change it..the reasons why were unclear, but it was infered to me that detonation in a 350 was at a diff frequency then on a 305, so a diff knock sensor was in order to detect it..


does this mean i need one made for my 400? or will the 350 one (or even the 305 one) work?

 

At one time I'd tried all the replacement K/S that Standard Ignition listed for a SBC. And I think there was a difference of about 3d between the lot. This was on an LG4, converted to TBI and a C3 ecm. While they do vary some, if it's just as a fail safe then I don't see a big problem, with being just being close. Least from what I've found.
YMMV