I'm getting massive knock retard at high loads high rpm. It pulls out as much retard as it can ( i've tested up to 16 deg in PE vs. spark retard)

- Fuel is ok!
- I've tested lowered the timing to 20 deg no luck.....

How common is it that a KS fail? and what are the symptoms?

How to determine if its a false knock?

Any tips/hints are welcome!!

/N.

 

I'm assuming your running iron heads correct?

What are you considering high rpm's?

As far as false knock goes I would listen very carefully and see if you hear anything rattling around, noisy valve train....etc etc etc. And exhaust rattle and or a cut-out too close to the motor will do it as well. How do your plugs look, are you running an aftermarket ignition, like MSD, ACCELL......!

 

Canfield al. heads.
MSD 6BTM ignition.
high rpm 4700-5500 rpm.......

I have NOT the belt to the supercharger on!

See sign and web page for complete setup info

 

If your postive that your not getting knock and that it is indeed false, then the easiest thing to do is what I did. I filled up with trick 101 unleaded and removed the wire from the Knock Sensor and then took a 3.9K ohm resistor and wired one end to ground and the other to the wire that used to go to the Knock Sensor. Now if you were getting false knock this will eliminate your problem. But if you still wanna beable to run 91 octane like I need to then you can also take an ohm meter and check the resistance of your Knock Sensor. The red lead of your meter to the connector on your sensor and the black wire of your meter the engine block. Should read from about 3700 to 4500 ohms. Mine was intermittant, one sec it would be an open circuit and then it would read 3600 ish then back to open....only thing that was done was the sensor was swapped from one motor to the new one...really kind of a weird failure but I guess it happens. Anyways sorry for the long post but this should get you to where you wanna be.

 

I've checked the resistans on the KS to 100.4 K Ohms ( I have a -89 som its correct, 90- has 3.9 k Ohms...)

/N.

 

With Alum heads I would imagine you could run close to 30* of timing before getting any back talk from the KS. You could put some 87 octane gas in it and see if it gets worse, than fill it up with some good stuff and see if it gets better. I would basically stick to working with what ever is free until you've exhausted all of them, then start thinking about money fixes Good Luck!