Vortec -> Carb now -> TBI

[PJG1173]

Ok, so I think I've collected enough parts for my carb to TBI swap. I've been working on soldering up my wire harness the last few nights. I started placing the sensors on the motor yesterday since it wasn't raining. I got to the knock sensor and ran into a problem. since I have block hugger headers the knock sensor won't fit between the collector and the block when put in the drain hole at the bottom of the block. Is there an alternate location to put the knock sensor or can I do like what the guy did in the below link?
http://www.chevytalk.org/fusionbb/sh...ca44c74730d78/

[RobertISaar]

that route has been suggested on TGO many times, so it must have merit.

[pmkls1]

I've wondered myself about mounting one in a similar method. The new style GM knock sensors are designed to mount in a similar manner with a thru-bolt that doesn't enter a water jacket. I'd think that it probably works ok with at most a little fine tuning to the knock parameters.

[RobertISaar]

some older applicatons didn't mount into a water jacket either.... see ~85 and up 60V6 applications for example. i don't think it's that critical.

[EagleMark]

That works fine. Although it does de-sensitize the reading a little. Very handy with conversions and to reduce false engine noise knock counts. Just have to verify knock counts when done. When in block I usually back off timing 2 degrees, with the elbow 4 degrees. I am conservative with spark and have never hurt a motor!

[pmkls1]

some older applicatons didn't mount into a water jacket either.... see ~85 and up 60V6 applications for example. i don't think it's that critical.

That makes sense as the Gen III LS engines use a standard threaded style knock sensor that doesn't mount into a water jacket either. I'm guessing that on at least some applications the mounting location of the knock sensor was a matter of convenience in order to avoid expensive block re-tooling maybe ?

[RobertISaar]

possibly. or just attempting to locate the sensor in a central spot, regardless of water jacket location.

[PJG1173]

Hmm would a bolt through LSx style work with a 7427?

[RobertISaar]

depends on resistance, and what kind of ESC setup you're using.

with older OBD1 stuff with the external ESC filter, they ran 100K ohm sensors.
with the OBD1 stuff that have ESC filters internal to the ECM(MEMCAL), they ran 3.9K ohm sensors.
when OBD2 happened, they moved back to 100K ohm sensors, but used a different style of connector.

so, if you could use an external knock filter with a 7427, entirely possible.

[CDeeZ]

Damnit, where is that little popcorn eatin smiley guy now that I need him. This is interesting stuff.

I think Grumpy was one of the first to suggest using a elbow mounted KS years back. Especially useful for quelling false knock counts from a rumpity rump engine, as Mark mentioned.

[EagleMark]

Damnit, where is that little popcorn eatin smiley guy now that I need him. This is interesting stuff.

I think Grumpy was one of the first to suggest using a elbow mounted KS years back. Especially useful for quelling false knock counts from a rumpity rump engine, as Mark mentioned.

He did. Also did a bunch of testing involving ESC modules and sensors. But I beleive it was lost as I looked pretty hard awhile ago to find it. I it was lost...

[JeepsAndGuns]

I have read about that a few times on here, but the first time I have seen a picture showing exactly how someone has done it. Very interesting way of doing it.
I really should give this a try. I have never been able to use my knock sensor because of false knock. It would be nice to be able to use it.

[Six_Shooter]

I've done it differently on a few applications.

On my Nissan 2.8L I6 (Using Delco EFI), I used a 45* brass "street elbow." I threaded the elbow in place of where I had the knock sensor, then threaded the knock sensor into it.

[pmkls1]

I have read about that a few times on here, but the first time I have seen a picture showing exactly how someone has done it. Very interesting way of doing it.
I really should give this a try. I have never been able to use my knock sensor because of false knock. It would be nice to be able to use it.

I have considered this as well. But, I do have some mechanical noise that may be leading to some of my false knock counts that I will be repairing and I will re-evaluate after I make the repairs. GM uses the thru-bolt style knock sensors on everything nowadays and there are multiple part numbers for them. The next time I have a chance to grab a couple from a junk engine I will check the resistance of them and see if there are any that may work with the 7427 memcal.

[1project2many]

I just picked the wrong knock sensor. :) When I built the '57 I used a sensor from a Saturn with 1.9 PFI engine and ran a 3/8" die over the 10mm threaded stud. Since the '57 engine mount is attached to the front of the block, I used one of the holes on the side of the block for the sensor. It picks up knock but it's not overly sensitive. And boy oh boy did I get blasted on GMECM for mentioning using a knock sensor from the wrong bore size engine to discourage false readings!

Mark, if you have some idea of a post, or a note, or how Grumpy's tests were worded I may have a few saved messages here. In the beginning I saved each and every post I saw come across those lists.