Offshoreonly.com - What thread is a knock sensor?

Offshoreonly.com (https://www.offshoreonly.com/forums/)

- General Q & A (https://www.offshoreonly.com/forums/general-q-20/)

- - What thread is a knock sensor? (https://www.offshoreonly.com/forums/general-q/292904-what-thread-knock-sensor.html)

Quote:

Originally Posted by HaxbySpeed (Post 3886026)

It doesn't change the frequency of the sensor, but it will effect it's sensitivity. The GM knock sensor that Merc commonly uses has a frequency of 10.5kHz. Different block locations can change it's sensitivity, putting them in brass y-blocks, etc. If your EFI system isn't capable of fine tuning the sensitivity then sometimes you have to move them around or use adapters to avoid detecting false knock. The block will drill and tap pretty easy, I'd put it there if you don't want to use the drain hole.

I think im going to put it in that boss,try to drill it and tap it the same as the factory other block,Figured Id start there .that should be the closest to factory as I can get. Only difference is the block is a denser better material,its diffidently heavier than the GM block,

thanks for all the help

Rob:drink:

I drilled the boss, it drilled real easy,tap bottomed so it doesn't thread all the way,but its enough.

just need to figure were to put the oil sensors now

Thanks
Rob

Quote:

Originally Posted by lakematdude (Post 3885474)

Knock sensors are very sensitive, It is very important that the knock sensor be torqued to the exact specification. Incorrect torquing will result in unsatisfactory performance.
Do not use sealer on threads.
Install knock sensor in engine block. Torque to 12-16 lb. ft. (16.3-21.7 N·m).

Depending on the old engine application the knock system came off of, You might be able to install the knock sensor in the upper location on a Y-fitting to use as a block drain as well for winter time.
Merc part number 22-8067051, Item #12,
http://www.mercruiserparts.com/Show_...rs+and+Sensors

See page 4B-22 for the idea,
http://www.boatfix.com/merc/Servmanl/16/16B4R2.PDF

Bringing up an old post....
I have a 94 454 mag efi I am replacing my knock sensor. could I use a knock sensor from a 94 454 chevy 3500 truck or will the frequency detection be different or not read properly to a merc knock sensor? Would it work the same and be a lot cheaper?