3.1 liter question.

p8ntman442 · Post by **p8ntman442** » Mon Oct 31, 2005 5:05 pm

the pickup is a mgnet attached to the block casting with 2 bolts. The pickup is about 1.5" long and curved to the radius of the harmonic ballancer.

I was thinking about the circuit, and Im pretty pissed that its a 24x signal and not a 21x signal, this means if I make a counter circuit, it will have to used the lowest common denominator of 7 and 24 which is (7x24) = 168. This means that you produce the 7 x signal you need every 24 revolutions of the crank. you would then have to average these values to get a signal that reads like the 7x from a regular engine.

The wheel has pretty much nothing to cut, its more of a positive inductance than a negative inductance wheel like a reg. 2.8 crank reluctor. you know instead of cuts in a blank you have material placed evenly to make the signal.

It shouldnt be too hard. I would have to make it digital, because car voltage sources are pretty unreliable. Id also have to deal with heat dissapation issues by moving it away from the block. All minor details.

DOnk hows oyur time frame on this project? This could take a while. I also believe there are aftermarket kits for this.

donk_316 · Post by **donk_316** » Mon Oct 31, 2005 5:18 pm

No rush!

p8ntman442 · Post by **p8ntman442** » Mon Oct 31, 2005 5:20 pm

found this on 60deg.

http://60degreev6.com/index.php?name=PN ... +ballancer

donk_316 · Post by **donk_316** » Mon Oct 31, 2005 5:31 pm

p8ntman442 wrote:found this on 60deg.

http://60degreev6.com/index.php?name=PN ... +ballancer

Ill talk to them and see what the deal is with that.

p8ntman442 · Post by **p8ntman442** » Mon Oct 31, 2005 5:42 pm

ok I did a lot of digging and found a pic. I had to crop it and blow it up in paint, but you can clearly see the ring around the back of the ballancer, which looks like the rungs of a ladder, and the pickup which is blue.

Shaun41178(2) · Post by **Shaun41178(2)** » Mon Oct 31, 2005 6:09 pm

when he says screen he is pretty close to describing it. I doubt I still have mine laying around here to take a pic of.

But basically take a thin metal plate about 1/2 inch wide and form it to the inside of hte harmonic balancer. Then cut a bunch of square holes in it about 1/4 inch apart with each hole being rectangle shaped. Thats what hte ring looks like.

If you were to use the 3X00 harmonic balancer you would also have to use the mounts and such for the gen 3 motor as well because the ribbing for the belt is incorporated into the balancer and not a separate pulley like the fiero has. Not sure how the dohc has it.

The Dark Side of Will · Mon Oct 31, 2005 9:37 pm

p8ntman442 wrote:ok I did a lot of digging and found a pic. I had to crop it and blow it up in paint, but you can clearly see the ring around the back of the ballancer, which looks like the rungs of a ladder, and the pickup which is blue.

Ahh... Ok. That looks similar to some Daimler-Chrysler setups. They typically have a screen like that on the perimeter of the flywheel... the large diameter gives it VERY good angular resolution.

Anyway... the pickup is bolted to a boss on the front cover, not the block, right? I have the resources available to weld up and machine a boss on the DOHC front cover...

The "screen" could be faked. The laser could cut a strip of sheet metal with the right holes which would then be wrapped into a circle and welded to a disk that the laser could also cut. Unfortunately, the laser can't do welding.

I think that setup might be workable on the DOHC.
Do you know where the signal from this sensor went in its native application? To the coil pack or directly to the ECM? Is there also a conventional crank sensor plug in the middle on the rear (right) bank of the engine?

There's a similar setup used on '96-'97 LT1's and OBDII Vortec 350's and 4.3's. It allows any SBC to be retrofitted with a crank reluctor and run on modern engine management.

p8ntman442 · Post by **p8ntman442** » Mon Oct 31, 2005 10:26 pm

The Dark Side of Will wrote:
Do you know where the signal from this sensor went in its native application? To the coil pack or directly to the ECM?

nope!

The Dark Side of Will wrote: Is there also a conventional crank sensor plug in the middle on the rear (right) bank of the engine?.

dont know

The Dark Side of Will wrote: There's a similar setup used on '96-'97 LT1's and OBDII Vortec 350's and 4.3's. It allows any SBC to be retrofitted with a crank reluctor and run on modern engine management.

ok!

I honestly was only doing the timing chain gasket for a few bucks on the weekend, didnt research it or think of it until later. Cutting a new screen and putting it on the ballancer you would just have to make sure your timing is correct. not too hard as the ballancer is keyed.

I think rather than doing all that work (unless you could do it yourself) it would be cheap and easy to build a counter circuit that changed the 24x signal to a 7x signal. a few resistors, capacitors and a 555 timer would cost like $2. That way a stock 3100 ballancer could be used whenever needed. This would reduce the cost of the modification dramatically. Not sure why you wouldnt want to approach the system in this way. Ill do a little more research on the circuitry involved.

p8ntman442 · Post by **p8ntman442** » Mon Oct 31, 2005 10:28 pm

here is the rest of the pic, you can see the pigtail for the pickup in the pic on the right, looks like 3 wire weatherpack connector going to the coil pack module, but thats a guess. Im sure someone on 60deg can identify where it goes. asked here link to 60 deg http://60degreev6.com/index.php?name=PN ... ic&p=65988

edit to say where these pics came from. Lots of good 3100 pics here.
http://3100autopics.tripod.com[/url]

The Dark Side of Will · Mon Oct 31, 2005 11:23 pm

p8ntman442 wrote: I think rather than doing all that work (unless you could do it yourself) it would be cheap and easy to build a counter circuit that changed the 24x signal to a 7x signal. a few resistors, capacitors and a 555 timer would cost like $2. That way a stock 3100 ballancer could be used whenever needed. This would reduce the cost of the modification dramatically. Not sure why you wouldnt want to approach the system in this way. Ill do a little more research on the circuitry involved.

A) I'd be a bit concerned about as much latency as averaging crank speed over seven revolutions (168 pulses of the 24x) is going to introduce into the system.

B) I think that signal adapters are just a band-aid and where feasible best results will be obtained by generating the correct signal in the first place.

C) In applications in which the 3100 balancer can not be used, the wheel will have to be fabbed anyway.

From some math recently done for a friend... a 4 cylinder with one pulse per ignition event will have less than 1 degree of timing error at 1000 RPM/s acceleration. A v6 will have 2/3 that, but by averaging the frequency over 7 revolutions as you describe, you could increase that error by as much as a factor of 21 (7 times the number of ignition events per revolution), which is obviously not good. I could do some math with moving averages, but I have a sneaking suspicion that would lead to calculus and it's 2330 right now...

Your V6/60 link no workie.

The Dark Side of Will · Sat Dec 31, 2005 1:49 am

Bump to rememberate.

Does not look like this would be too hard to do on a DOHC engine with non-reluctor forged crank.

p8ntman442 · Post by **p8ntman442** » Wed Jan 04, 2006 4:19 pm

The Dark Side of Will wrote:Bump to rememberate.

Does not look like this would be too hard to do on a DOHC engine with non-reluctor forged crank.

check donks 3.4 thread it has one already. we discussed in there.

The Dark Side of Will · Wed Jan 04, 2006 8:03 pm

Which thread is that exactly?

I know about his forged crank, as I'm buying it.

p8ntman442 · Post by **p8ntman442** » Fri Jan 06, 2006 7:13 pm

donks putting a 3.4 dohc in an indy thread. if i wasnt running on 44kbps id link you to it, but, you will have to dig. If all goes as planned i will pick up my 92 3.4 tomorrow. but with my luck it wont happen.