Fab'ing up a Knock Sensor install 300x

[Liberator*21]

As most of you already know, I "Pop'd" the motor in Aug of this year and this whole project is started because of this:






This project deals in adding a "Knock Sensor System" to any early Carb or EFI motor and some fabrication. Even though mine is a 01' 300x, this can be done on any motor with the same basic system. I bought a stand alone Knock Sensor Kit for a guy in Canada who makes these, cost: $133.00 USD.

Very well done kit and the guy is great to deal with on the technical side as well.
This is the complete kit as received, install & tuning instructions, 2 Knock Sensors, LED knock warning light,
control module and all the wiring needed (you specify wire length needed when ordering). The little black box
has a circuit board and rheostat in it. The rheostat is where you'll fine tune the frequencies picked up by the
sensors and then a low voltage output warning signal is sent to the LED Warning light that you'd mount
somewhere on the dash or steering column:









I started by placing one sensor onto each bank, outer stud @ #3 & #4 as shown:




After attaching the knock sensors, I mocked up the wiring temporarily for a test. I used a spring loaded center
punch to perform the test starting with the center cylinders adjusting the spring pressure of the punch
in small increments until the LED warning light would flash signaling a knock. I then moved up and down testing
in the same method as I did on the center cylinders using the spring loaded punch. Couldn't get a flash on the
warning LED until I cranked up the spring pressure in the punch greatly. This told me that knock signals from
1,2,5 &6 may go undetected due to the lack of sensitivity to read or sense a knock further away from the sensor.

This lead me to study up a little and spoke to a friend who's a mechanic at a Porsche dealership. It seems that
Porsche had the same problem and there fix was to make a bridge linking the 3 cylinders together under one
sensor rather than putting 1 sensor on each cylinder. So I took that idea and decide to duplicate what they
already figured out. Grabbed a piece of 1/4" Aluminum plate and machined a sensor bridge for mounting on the heads to cover all 3 cylinders each side.

Porsche Knock Sensor Bridge across 3 cylinders w/one knock sensor:





So here's my version and it works great;




Video clip, showing sensor mounted on my bridge plate, spring loaded punch used to test and you'll have look
at the top of the steering wheel for the LED to flash (temp mounted);

http://s177.photobucket.com/albums/w...t=KnockVid.mp4

[berg969]

Looks like it is available from merc as well
look at part# 64
http://www.mercruiserparts.com/Show_...ck+and+End+Cap

[Liberator*21]

Looks like it is available from merc as well
look at part# 64
http://www.mercruiserparts.com/Show_...ck+and+End+Cap

Good find, but @ $80 a piece and nothing else makes the kit I used ($133) seem like a bargin..........

[frontline]

Great work!!!

[demag67]

On cars the knock sensor is in the block towards the middle. wouldn't you want it to be in the same location? always thought you would get a false reading. just asking since i want to do the same to my 300's also.

[Liberator*21]

On cars the knock sensor is in the block towards the middle. wouldn't you want it to be in the same location? always thought you would get a false reading. just asking since i want to do the same to my 300's also.

K/Sensors are mounted in a numerous places on cars, marine motors, snowmobiles etc. I don't think there is one perfect spot that is used across all types. My main reason is for detonation and my location works for that.

[demag67]

Thanks. I was thinki g about this and was wondering how I could pull it off. I will go to the heads instead and make things a lot easier