K Series Timing Chain Covers

[Banjo]

Finally got around to fitting the sensor to the timing chain cover at the weekend. Simply removed the camshaft sprocket, & drilled a small hole in one of the "spokes" of the sprocket. There is plenty of meat in the casting at those points. I used a rare earth magnet 10mm in dia. & 25mm long. Determine which is north pole, & which is south pole, & mark accordingly, as the Hall Effect sensor I used, (Honeywell model SR3F-A1) is unipolar, and only operates to a south pole. South Pole must face out to the front of the sprocket. I liberally coated the hole & the magnet with Araldite, and ensured the face of the south pole was flush with the front outer face of the sprocket.

 

 

Magnets are also available in a "screw in" package in plastic or metal case. This might work well, as it doesn't require Araldite to hold it in. "Loctite only". Only disadvantage is the magnetic strength of these smaller magnets, will probably require a smaller gap between pole face & sensor.

 

 

 

I used another cover off a 4K or 5K instead of the original 3K one, so simply ground the "ribs" off the inner side of the casting and drilled a hole for the sensor (14mm) There is quite a good thickess of metal in the timing chain cover, so for permanent use on a road car, I would tap the hole (M14 x 1.0), and only use the outer locknut, so the sensor could be removed without removing cover, if the Hall Effect sensor ever needed to be replaced.

 

The sensor has a threaded barrel & lock nuts, so it's distance between sensing face & magnet south face can be adjusted.

 

I hooked up the sensor to an LED, so I could see it switch, when the engine was rotated. The sensor reliably switched with gaps of 1mm to 10mm, so I set it at 5mm.

 

 

I had previously tested the sensor on the bench with an oscilloscope, and it produced a very clean sharp pulse about 1.2m/S wide at around 5200 rpm. I think I read in the specs, that they are good to about 100kHz, so speed is not an issue.

 

This sensor should provide a very reliable "synch" signal for any after market ECU, requiring one.

 

Unlike the crankshaft pulley ones, it is hidden away, fully protected, and is guaranteed operation up to 125 deg C.

 

I will fit one to my road car next time I have the radiator out, and hook it up to a simple tacho for a month or two, to see how it performs long term, before trying it with my Haltech E6K.

 

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I did learn that all 3K/4K/5K sumps mounting holes & timing chain covers are not identical.

 

The 3K sump's very two front flange mounting holes, (one on each side), do not line up with the timing chain cover from the 4K or 5K I used.

 

 

Cheers Banjo

Edited May 4, 2015 by Banjo