Knock Sensor location in early model block
 

Where would you mount the knock sensor in a pre emission era block?

Re: Knock Sensor location in early model block
 

Exactly where it is in a post-emissions-era block.

Re: Knock Sensor location in early model block
 

My 90 has a threaded hole on the passenger side of the block for the knock sensor.

I'll be putting in an early 70's block which doesn't have the threaded hole for the sensor.

So where would I put the knock sensor in the early block?

Re: Knock Sensor location in early model block
 

I've always used one of the block drain holes on whichever side the wiring fits the best.

Re: Knock Sensor location in early model block
 

Yes, it does.

Re: Knock Sensor location in early model block
 

I agree... it may have a plug in it, but the hole is there.

Re: Knock Sensor location in early model block
 

i prefer putting it on the other side of the block away from the starter, it makes changing the starter a little easier.

Re: Knock Sensor location in early model block
 

The ideal ( though not necessarily practical ) spot is in the valley dead center in the engine.
That way, the sensitivity and response is as close as possible to the same on all cylinders, though the difference is debatable.

Re: Knock Sensor location in early model block
 

I did read some test from Bosch and they mentioned that the 3th cylinder from the front would be the perfect position.
I our case it would be close to cylinders #5 or #6.

I have put an elbow at the hole to get more space in relation to the "block hugger" headers. The engine has started yet but I hope that it works, although the sensitivity will be lower.

Regards,
Cobra289

Re: Knock Sensor location in early model block
 

that worries me!! will that work at all with that elbow? im not sure, hope some else can chime in on this!

Re: Knock Sensor location in early model block
 

I am hijacking the original thread, but I think that it was done with it!

I recall Grumpy postulate several times that we can use an 45* elbow to desensitize the sensor.
So a 90* elbow should not make to much change and this theory, the spot is free from other parts so that would be not a problem.

What I am worry is about the Teflon tape that probably will reduce the earth path, but because the coolant there the earth should use that path.
At least I hope that works that way.

I don't know where the people put the knock sensor when they use the block hugger headers (SB) because there is no room for it, and I can tell you I have melt down several connectors.

Perhaps I need to start a new thread.

Regards,
Cobra289

Re: Knock Sensor location in early model block
 

Technically the NPT thread seals along the thread face where the tape will be scraped off as the parts are tightened together. The remaining tape will seal the helical root of the threads where metal to metal contact does not occur. Just tightening very well should allow a path to ground.
You could solder a wire to the case of the sensor to get the earth path if the tape is wrapped too thick to allow metal to metal contact because of leakage .

Re: Knock Sensor location in early model block
 

Hi JP86SS,
Normally I use the Teflon paste to seal, but this time I was forced to use the tape to have it fixed at this angle.
I though that the NPT thread will engage metal to metal, because one of the Teflon tape problems is that you are not allow to back up a bit the fitting, due that it will destroy the seal.

Anyway, how much will be de-sensitize? we will see. I am happy if the ECM recognize it when the Knock Sensor control happens.
If I don't get any malfunction code than I suppose that is OK.

I have had some delay with the engine (three ECM's to wiring it up) and was forced to change the schedule so the new plan say that halve September would be the first firing.

Thanks for the information.
Regards,
Cobra289 (Carlos)

Re: Knock Sensor location in early model block
 

I put a knock sensor in my 1967 327, so anyone has the hole for it, it's a coolant drain like was already mentioned.

Re: Knock Sensor location in early model block
 

A knock sensor is nothing more than a microphone, with some added circuitry to tailor the response. If space is a problem, I'd screw it in the intake manifold somewhere, else any threaded hole you can find will work fine. The knock sensor is one of the least sophisticated parts on the entire vehicle. ( not priced accordingly )

Re: Knock Sensor location in early model block
 

A knock sensor in the intake is not a good thing. It is calibrated to be in the block.

Re: Knock Sensor location in early model block
 

Hi!

A bit out of theme but did found this information about Knock Sensors Sounds.

Looks like this guy did some nice work.
Perhaps some one is interested in this project.

http://home.netcom.com/~bsundahl/kno...tm#spectrogram

Regards,
Cobra289

Re: Knock Sensor location in early model block
 

Most of the TPI streetrod apps I've worked on will allow you to put the knock sensor on the driver's side I believe. It seems that the pass side hits the collector on block huggers.

Re: Knock Sensor location in early model block
 

certain year tbi 4.3's have a knock sensor that thread into the back of the head.

thats also an option

Re: Knock Sensor location in early model block
 

Hi
Looking in more detail to the drivers side drain and compared to the passengers side drain, tell me that both are located at the same spot, just behind (1/2") from the 5th bolt of the oil pan, so we have the same problem.

But there is a threaded boss at the drivers side that it not in contact with the coolant.
Probably drill thought the coolant passages and install there the knock sensor will be a nice solution.
I think that the drilling is needed due to that the sensor will than sens the shock waves at the coolant.

Check the picture perhaps other old engine blocs have these provision (boss) too!

Any thoughts on this idea?

Regards,
Cobra289

Re: Knock Sensor location in early model block
 

If you wanted to use that location (I don't recall what that was originally intended for), I would leave it as a blind hole. Looking at late model KS locations they use blind holes. I'm not sure if this is a maintenance deal, so that no coolant will be spilled if if it's to keep the coolant off the sensor, or maybe jsut simply to avoid possible leaks.

Re: Knock Sensor location in early model block
 

Just so we're clear...
A knock sensor is nothing more than a microphone.

Thay are not calibrated to anything. The FILTER in the module may have an acoustic trim closer to the resonance of the bore diameter, and it may not. ( stroke distance and chamber volume are variable, and dynamic, bore is not )
Sound propogates quite well in solid iron.
You can put it *anywhere* it is in direct mechanical contact with the block, such as screwed into an intake manifold, power steering pump bracket, etc.
Clamp it onto the bell housing, or oil pan bolt with a vice grip. It'll work as well as anywhere.
( and is rediculously easy to test )
The ideal location, is as close to the squish area of the chamber in question as possible for a faster ( not more sensitive ) response, but practicly speaking, it doesn't matter.

Re: Knock Sensor location in early model block
 

Cobra

Thanks for posting a nicely dressed SBC.

The right most highlighted hole was originally used for mechanical clutch setups. Back in 60's 'three on tree' used a Z-bar which was pivot arrangement between clutch paddle and clutch bar. These were always problematic due to engine torque - the other pivot ball mounted on the frame.
KS sensors are tuned frequency microphones. For example, Delphi offers KS having resonant frequencies at 5,200 Hz, 6,000 Hz, 7,000 Hz, and 8,000 Hz. During engine testing a spectrum analyzer is used to determine fundamental frequency of knocking sound. Each engine type (displacement, cylinder configuration) will have slightly different knock frequency.