Lexanlarry

Who makes a knock sensor for a carb motor to warn u before detonation. Do they work well?

Smitty

iTrader: (1)

Check Summit or Jeg's I think they will have something for you.

Also the Gen V Merc carbed motors had a knock sensor hooked to the ignition module. What set up do you have ??

Lexanlarry

The motors are carbed blower motors.

Griff

Knock sensors do not warn you before detonation. The alert you when detonation starts and depending on the set up, they will retard the ignition timing.

Smitty

iTrader: (1)

Griff is correct. A sensor truly should be used to change timing if it senses knock. If your igntion system is not capable of doing that, it will not work.

How about installing wideband oxygen sensors to monitor air/fuel ratio ?? That is the best indicator of what is happening with mixture.

John at J&S

iTrader: (1)

Here's a video of a J&S knock retard unit on a Ford Lightning. The version shown is for coil on plug ignition and shows which cylinders are being retarded (knocking):

http://www.youtube.com/watch?v=CeuD2-GIlb0

The truck in the video had previously been tuned for 91 octane and had been running that tune for two years with no knock control. After installing the controller and verifying it would control knock on 89 octane, the owner continued to run it on 89 for a month then checked the plugs and found no evidence of detonation.

In the video we are cruising the I-5 freeway near Camp Pendleton and accelerate from 70 to 90 to demonstrate the unit. Boost was held to 8 psi, though at WOT it would make 19 psi.

The video was made in April of '08. A few weeks after the video he changed pulleys to allow up to 21psi. Nearly five years later the truck is still running the stock block and has never been apart. It's still running the same tune on sub par fuel (mix of 89 and 91).

The owner is "bgstew6", a moderator on lightningrodder.

Rookie

iTrader: (4)

Here is what I am putting together. I am going to use the knock module from a Thunderbolt ignition (basic GM module). When The module sees detonation (knock) I am going to source the 5vDC Knock Module Signal Wire to a solid state relay that will then souce ground (-) to my ignition retard wire. This will then retard my ignition X degrees that I set it for. You could also use the sourced 5vDC to an led light on the dash if you do not have an ignition with retard capabilities.

Anyone see any problems with my plan?
I have Crane HI6M ignitions

Page 20 lays out the wire diagram
http://www.boatfix.com/merc/Servmanl/16/16B4R2.PDF