Slant 6 lean burn distributor info...

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Bill Dedman

Bill Dedman

bill dedman
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Slant 6 lean burn distributor info...
Can someone with experience regarding the "no manual or vacuum advance," dual pickup, slant six electronic distributors answer me a question here, please?

I need to know the amount of difference ON THE CRANK in spark timing, between the "start" mode pickup coil and the "run" pickup coils in the Lean Burn, slant six distributors.

Is it like, maybe 10 degrees, or 5 0r 6??? I have no idea nor do I know where to go for that information.

I am building an experimental, turbocharged, slant six and want to run a spark system with NO ADVANCE curve of any kind. Just a locked plate.

I understand that the Lean Burn distributors had no advance mechanisms. either mechanical or vacuum. I just want to lock it at 18 degrees.

But, if they had two sets of pickups (coils) perhaps 6 degrees apart, I might be able to run off that advanced pickup, which could give me 24 degrees for a couple of seconds, while the turbo was spooling up, then I could switch over to the other one, which would retard it back to 18 degrees when boost came up over, say, 15 pounds...

A good 60-foot time is what I am looking for...

I have thought about giving the old gal a 50-hp shot of nitrous for one (1) second at launch, but would rather not fool wih the laughing gas, if I can get it done any other way...

Any information will be appreciated. I just need to know what the offset is for the two pickups, in crank degrees..

Thanks, in advance..

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Bill, in Conway, Arkansas
"I KNEW THE LIGHT WAS GREEN!! I was waiting for the BOOST!!!!
 
Bill Dedman said:
Slant 6 lean burn distributor info...
Can someone with experience regarding the "no manual or vacuum advance," dual pickup, slant six electronic distributors answer me a question here, please?

I need to know the amount of difference ON THE CRANK in spark timing, between the "start" mode pickup coil and the "run" pickup coils in the Lean Burn, slant six distributors.

Is it like, maybe 10 degrees, or 5 0r 6??? I have no idea nor do I know where to go for that information.

I am building an experimental, turbocharged, slant six and want to run a spark system with NO ADVANCE curve of any kind. Just a locked plate.

I understand that the Lean Burn distributors had no advance mechanisms. either mechanical or vacuum. I just want to lock it at 18 degrees.

But, if they had two sets of pickups (coils) perhaps 6 degrees apart, I might be able to run off that advanced pickup, which could give me 24 degrees for a couple of seconds, while the turbo was spooling up, then I could switch over to the other one, which would retard it back to 18 degrees when boost came up over, say, 15 pounds...

A good 60-foot time is what I am looking for...

I have thought about giving the old gal a 50-hp shot of nitrous for one (1) second at launch, but would rather not fool wih the laughing gas, if I can get it done any other way...

Any information will be appreciated. I just need to know what the offset is for the two pickups, in crank degrees..

Thanks, in advance..

__________________
image.php
Bill, in Conway, Arkansas
"I KNEW THE LIGHT WAS GREEN!! I was waiting for the BOOST!!!!
Click to expand...

Bump
 
Bill,

Use a protractor to measure the angle, multiply the distributor degrees by 2 for crank degrees. Another way is to use the engine and degree wheel. Mark a reluctor nub, rotate crank to center it on the first pickup, record crank angle, then move nub by rotating crank to second pickup, subtract first crank reading from second.

If the measurement is more than 120 degrees, subtract 120, repeat as needed.

Wish you were closer. I would help you with programmable advance for RPM and MAP. PM for more details. I did one for 2.2L Mopar turbo.
 
KitCarlson said:
Bill,

Use a protractor to measure the angle, multiply the distributor degrees by 2 for crank degrees. Another way is to use the engine and degree wheel. Mark a reluctor nub, rotate crank to center it on the first pickup, record crank angle, then move nub by rotating crank to second pickup, subtract first crank reading from second.

If the measurement is more than 120 degrees, subtract 120, repeat as needed.

Wish you were closer. I would help you with programmable advance for RPM and MAP. PM for more details. I did one for 2.2L Mopar turbo.
Click to expand...

Thanks for the advice, Kit.

I don't have one of these distributors. Yet. But, I will soon. I ordered a new one from Rock Auto (probably a rebuilt, not "new," actually), but that's of no importance in this instance in that there's no centrifugal advance mechanism nor a vacuum advance mechanism to wear out.

So, why am I asking this odd question?

I have a ****-eyed plan to use the two pickups like this:

There is NO spark advance curve in these distributors, and that's the way I want it. My engine, a turbocharged slant six, a race-only application (NO street driving, ever) needs 18 degrees of spark advance, PERIOD. That's crankshaft degrees. Boosted motors have no need for the usual 34-36 degrees advance of normally-aspirated motors, because the flame front travels across the combustion chamber in about half the time, under boost, as would a normally-aspirated spark "event."

At least, that's what everyone with experience with these things, tells me.

So, why two pickups?

The 18-degree figure is a maximum advance I figure the engine will tolerate without detonation, at boost levels over say, 15 pounds (this engine will see upwards of 25 pounds, and maybe more, ultimately.)

My experience with normally-aspirated drag racing engines has showed me that torque is greatly enhanced at low rpm's when a lot of spark advance is present.

Spooling the turbo at low rpm as quickly as possible, is my goal.

When the engine is in the process of trying to spool the turbo at stall (which will probably be 2,300-3,000 rpm,) the boost is still low and it will tolerate more spark advance... and that additional spark advance will enhance torque at that rpm. THAT will spool the turbo more quickly, is the plan.

Utilizing two pickups, one offset from the other, will give me two options as far as static timing goes; one "advanced" from the other, depending on which pickup is operational at the time..

If the difference on the crank, between the two pickups is, say, 6 degrees, I can utilize the "advanced" signal to give me 24 degrees of spark advance during stall-starting the 904 automatic, (while the rpm and boost is low... say, under 15 pounds) and switch over to the other, "6-degrees retarded" pickup, for the rest of the trip (bringing the timing back to 18 degrees, at anything over 15 pounds of boost.)

It's just an attempt to minimize "spool-up" time, leaving the gate, and it's JUST an experiment. I have no idea whether it will work.

If it doesn't, I may need to install a nitrous oxide system to spray the intake system for one second, or so, as the car leaves the line and the boost needs enhancement.

As you can see from all this, I want this thing to have the power necessary RIGHT NOW, leaving the line, for good 60-foot times.

1.40 would be good. :D

Maybe I won't need any of this, but I think I will; small-engines with turbos seem to need help in the first second of launch, or so it seems to me. The engine is only 234 cubic inches.... that's small.

This will be interesting... LOL!

Thanks a lot for your interest!!!:blob:

Bill
PS This is an "old school" build; no EFI and no computer-aided spark. No computer, period.
 
Bill,

I may be able to help. If you use two ignition systems and power only the one you want, it might work. Connect the coil (-) connections together. The un-powered may not be able to pull the coil low, so the powered one controls the ignition. This is a common method used in electronics, called open collector OR-ing. A SPDT relay could be used with an adjustable Hobbs pressure switch to control the power selection. The coil will need power when either ignition is powered.

I have not tested this, but it might work with the Mopar box, and GM HEI. The mopar boxes will need ballast.
 
74DartSwinger360 said:
Just get rid of the lean burn and run chebby HEI I did it on my 1983 Mirada and it ran much better. PM Me with Questions
Click to expand...


The HEI has a mechanical curve that I don't need. I want a locked plate. I don't need the vacuum advance, either. But, this dual pickup system might give me the capability to run more advance that the 18 degrees I need (once boost goes above 15 pounds,) by running the MSD 6-AL digital system off the "advanced" pickup until I get the turbo spooled and the boost goes over 15 pounds.


That would HOPEFULLY give me a quicker spool-up (with the additional spark advance) until I switch over to the "retarded" pickup, once the boost goes over 15 pounds.

That's the plan, anyway...

Thanks for your input!!! I appreciate it.:D
 
easiest thing i can think of is to run the MSD lead (green i think) to both pickups... now between the pickups and the (purple??) lead run a two pole switch so you can just complete the circuit between either pickups at will...

now if you really wanted to get tricky you could figure out a way to have a pressure switch or something hooked up to relays instead of a switch...

it would automatically switch between pickups depending on boost levels...

all this being based on the idea you can have either a switch controlled by a adjustable pressure switch or MAP sensor lol...

Ya dig?
 
KitCarlson said:
Bill,

I may be able to help. If you use two ignition systems and power only the one you want, it might work. Connect the coil (-) connections together. The un-powered may not be able to pull the coil low, so the powered one controls the ignition. This is a common method used in electronics, called open collector OR-ing. A SPDT relay could be used with an adjustable Hobbs pressure switch to control the power selection. The coil will need power when either ignition is powered.

I have not tested this, but it might work with the Mopar box, and GM HEI. The mopar boxes will need ballast.
Click to expand...


Only one of the pickups would ever be activated at any one time. I would use a Hobbs-switch activated DPDT switch to automatically switch between pickups (only ONE coil) so that below 15 PSI I'd be using the "advanced" pickup and over 15 PSI I'd be using the "retarded" pickup.

I think that's about as complicated as I need to make it.


That's with a Lean Burn (no advance mechanism of any kind) dual-pickup distributor hooked to the double-pole/double-throw Hobbs boost-activated switch, which would then go to the MSD 6-AL digital box, and then to the coil.

Any reason why this won't work?

I'm open to suggestions, naturally.:D

Thanks again for your interest and comments!
 
here is a ROUGH diagram...
 

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I think the trigger happens when the VR signal falls to zero. The switch-over, may create an undesired ignition event. At some time, that might be very undesirable. Mechanical switches also bounce, in the closure process. In any case it important to keep the VR wiring short to help minimize EMI false triggering.

I do testing of electronic advance using simulated distributor signals, and with battery power drill to rotate distributor. I then capture ignition events with logic analyzer. I run the whole gamut of RPM and MAP. It is then possible to know what happens with certainty.

It is possible to do something similar by using a drill to spin your distributor and trigger a scope by the Hobbs switch to check the ignition events in that time proximity. If a multi-channel scope is available also monitor the VR signal. This is a test that should be repeated several times to insure it is truly glitch free. If there is a problem it might be possible to use make before break switching, or use pull-up on VR input as solution.

I am guessing ....
 
KitCarlson said:
I think the trigger happens when the VR signal falls to zero. The switch-over, may create an undesired ignition event. At some time, that might be very undesirable. Mechanical switches also bounce, in the closure process. In any case it important to keep the VR wiring short to help minimize EMI false triggering.

I do testing of electronic advance using simulated distributor signals, and with battery power drill to rotate distributor. I then capture ignition events with logic analyzer. I run the whole gamut of RPM and MAP. It is then possible to know what happens with certainty.

It is possible to do something similar by using a drill to spin your distributor and trigger a scope by the Hobbs switch to check the ignition events in that time proximity. If a multi-channel scope is available also monitor the VR signal. This is a test that should be repeated several times to insure it is truly glitch free. If there is a problem it might be possible to use ake before break switching, or use pull-up on VR input as solution.

I am guessing ....
Click to expand...

There is something you two guys (Kid and Kit) need to understand here.

I AM AN ELECTRONICS IGNORAMOUS.

That is NOT an attempt at humor.

I am in NO WAY, competent to sit in judgment on your suggestions, though I will admit to understanding SOME of what's going on here.

Kit talks way over my head and I must apologize for my lack of understanding, though I have a BASIC understanding of what is needed here.

Kid draws me a diagram that is simple enough that I think I really DO understand it, except he puts someting called a "MAP" in the picture, which I thought was a fuel metering sensor (air flow) for fuel injection setups, knowing full well that our car is carburated. So, THAT confused me.:disgust:

Now, I realize that my suggestion that I needed a double -pole/double-throw switch was in error, and I should have agreed with Kit's original suggestion for a single-pole/double throw switch.

This SHOULD be simple, but I am BARELY smart enough to realize that what Kit said about the switchover causing an unintended ignition event is a very definite possibility if indeed, the MSD fires on a "break" rather than a "make" cycle.

Not good.

Here's an idea I had about that:

I have a friend who races a healthy 1300 Kawasaki bike with goodies, and shifting that bike without using a clutch is done by interrupting the ignition for a micro-second to relieve the drivetrain of stress on each shift. The gear-change can then be made without closing the throttle.

Would it be possible to use that "ignition-interrupter" for a miniscule amount of time, while the shift from the "advanced" magnetic pickup" to the other one, or would that not help?

Seems like if it were timed to interrupt the circuit BEFORE the next "make" cycle were begun, it might could work?

Or, is that even possible?

All of a sudden, this "simple idea" isn't so simple, anymore.:eek:ops:

Let me know what you think, guys... I am not the sharpest knife in the drawer, by a long shot...:violent1:
 
Bill Dedman said:
There is something you two guys (Kid and Kit) need to understand here.

I AM AN ELECTRONICS IGNORAMOUS.

That is NOT an attempt at humor.

I am in NO WAY, competent to sit in judgment on your suggestions, though I will admit to understanding SOME of what's going on here.

Kit talks way over my head and I must apologize for my lack of understanding, though I have a BASIC understanding of what is needed here.

Kid draws me a diagram that is simple enough that I think I really DO understand it, except he puts someting called a "MAP" in the picture, which I thought was a fuel metering sensor (air flow) for fuel injection setups, knowing full well that our car is carburated. So, THAT confused me.:disgust:

Now, I realize that my suggestion that I needed a double -pole/double-throw switch was in error, and I should have agreed with Kit's original suggestion for a single-pole/double throw switch.

This SHOULD be sim[le, but I AM brely smart enough to realize that what Kit said about the switchover causing an unintended ignition event is a very defite possibility id indeed, the MSD fires on a "break" rather than a "make" cycle.

Not good.

Here's an ifea I had about that:

I have a friend who races a healthy 1300 Kawasaki bike with goodies, and shifting that bike without using a clutch is done by interrupting the ignition for a micro-second to relieve the drivetrain of stress on each shift. The gear-change can then be made without lifting the throttle.

Would it be possible to use that "ignition-interrupter" for a miniscule amount of time, while the shift from the "advanced" magnetic pickup" to the other one, or would tht not help?

Seems like if it were timed to interrupt the circuit BEFORE the next "make" cycle were begun, it might could work?

Or, is that even possible?

All of a sudden, this "simple idea" isn't so simple, anymore.:eek:ops:

Let me know what you think, guys... I am not the sharpest knife in the drawer, by a long shot...:violent1:
Click to expand...


a MAP (Manifold Absolute Pressure sensor) reads the manifold pressure, or vacuum... all it does is use a reference voltage and outputs another voltage like an O2 sensor... its just a sensor...
 
805moparkid said:
a MAP (Manifold Absolute Pressure sensor) reads the manifold pressure, or vacuum... all it does is use a reference voltage and outputs another voltage like an O2 sensor... its just a sensor...
Click to expand...


I KNEW THAT!!!

(No, I didn't!!!)

Thanks for the information!

Now, realizing that "Hobbs switch" is about as technical as I can handle, what will a MAP sensor do for me that a Hobbs switch won't? Anything?

I am not trying to be a smartass; I really AM that ignorant. I just wanted to keep this setup as simple as I could... and adding things I am not familiar with "MAP sensors") is not going down that road, is it?

Once again, I am asking...

The whole schleemel is motivated by my desire to generate as good a 60-foot time as I can with this turkey. If anybody beats this car, (and, of course, they will,) I want them to have to catch it and drive around it.

I don't think a hard-leaving turbocharged car is an impossibility. Time may prove me wrong, but I'm trying to give it my best shot.

I'd LIKE to get this done without resorting to a trans-brake, but, I dunno.... gonna try some other things first. I don't much like 'em (trans-brakes) for the egregious way they treat the drivetrain... I'm not made out of money.

We'll have this old tub running one of these days soon, and can try some stuff....

Wish us luck!!:prayer::prayer::prayer::prayer::prayer:
 

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Bill I thought you already had a MSD btm it will retard your time up to 15 degrees or 1 degree per psi of boost up till 15 psi of boost
 
One more thing Bill I've doing a lot of research on the new turbos offered today like the one Tom is run pte6262 and its a amazing little piece of hardware it starts making boost at around 2000 rpm's and its at full boost pressure at about 5500 rpm

My turbo has a bad seal and will probably need a new center section and of course to replace it its gone to cost me almost as much as a new one so I'm thinking about shelling out some extra funds and just buy a new one
Bill I get so close to getting this little money pit going and bam got drop some more coin
But the way I'm looking at it I'm all in right now and I'm just going to let the chips fly
Aaron
 
srixon4406 said:
Bill I thought you already had a MSD btm it will retard your time up to 15 degrees or 1 degree per psi of boost up till 15 psi of boost
Click to expand...


I have one of those on my V8 car. I don't think I'll need it on this /6, with the Lean Burn distributor; we'll see...

I think the BTM module is not as powerful a spark (it's only 42,000 volts and not an MSD (multiple spark discharge) unit.) It's analog, I believe, or at least the one I have is. I think the 6-AL digital is better-suited to firing under 25 pounds of boost...

Just my opinion... (my V8 car ony runs 10 pounds...)
 
srixon4406 said:
Bill I thought you already had a MSD btm it will retard your time up to 15 degrees or 1 degree per psi of boost up till 15 psi of boost
Click to expand...

The one I have, has a selector knob on the dash that allows you to select retarding the spark one, two, or three degrees for every pound of boost it sees, up to fifteen. Or, select "no retard."

It IS pretty handy...:blob:


But, I only need about 6-8 degrees of retard, and I'll be making 15 pounds of boost with this motor in probably less than 2 seconds, so even set on one (1) degree of retard (per pound of boost), the MSD Boostmaster would be retarding a lot more than the amount that I need. I'd have to set my initial timing at 33 degrees to get it back down to 18 when the boost kicks in, and I don't want to set the initial that high... I don't see this thing needing more than 24 degrees under ANY circumstances, but I could be wrong.


Maybe if it were an O-Ringed block, it might live with that much initial. But at this point, it's not.

Like I said, I may have to give it a 1-second shot of nitrous at the launch... but, probably no more than 1-second...

We'll see.
 
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