Reverse Rotation Distributor - Any issues?

[ShelGame]

I did at first then moved it, about a year later, I had a few threads about it. I didn't like the fact that you had to remove the intake to do any servicing of the cap, rotor or HEP.

Also, see my sig,








The HEP needs to be rotated 180 because the firing order is altered and the one PU is the injector syn, so if you don't rotate the HEP, it won't know when to sync. That's what I was told, haven't tried to run it without moving the HEP, maybe I should try.

I simply broke off the tabs on the harness connectors so you can swap them without modding anything and ground off the locator on the HEP.

Hmm, nope not buyin' it. Think about it. What is the difference between rotating the HEP and rotating the whole distributor housing? None. Nada. Nichts. Swapping the HEP connectors changes the 'old' ref picjup to the 'new' sync pickup; and vice-versa. You have to move plug wires around anyway, so I don't see that being any reason to rotate the HEP.

Anyway, I'll post the sketches of my low-profile distributor build when I get then done. And pics once I start building it.

if I have to move the HEP 180*, I'll eat my words...

[rbryant]

Hmm, nope not buyin' it. Think about it. What is the difference between rotating the HEP and rotating the whole distributor housing? None. Nada. Nichts. Swapping the HEP connectors changes the 'old' ref picjup to the 'new' sync pickup; and vice-versa. You have to move plug wires around anyway, so I don't see that being any reason to rotate the HEP.

Anyway, I'll post the sketches of my low-profile distributor build when I get then done. And pics once I start building it.

if I have to move the HEP 180*, I'll eat my words...

Look at the HEP its self.

The HEP sensors aren't 180 degrees apart from each other. That means that it is different when not turned 180.

If you don't flip it over and you run it then everything will be off by some degree (probably 10-15 but I didn't measure and this is from memory). Perhaps you can fix that in SW but for guys running stock electronics it would be a problem.

-Rich

---------- Post added at 09:16 AM ---------- Previous post was at 09:08 AM ----------

And, yes, you do have to move the shutter. I still think this needs to be more precise than maybe Dave's instructions make it. If the shutter is 'off' relative to the rotor, then the rotor will lose contact with the cap before the nend of the dwell period (basically a mechanical dwell limit) resulting in a loss of spark energy. Maybe this is only small, but it is possible if the shutter is not placed precisely.

If you look closely at my picture you can see why it is accurate. It doesn't show well but the shutter holes that don't have rivets in them still slide over the original tabs that I ground the tops off from.

I just grind the tops off from the plastic rivets it leaves 4 tabs on the plastic piece. There are 8 holes in the shutter wheel so you just turn it and push it on over the 4 tabs. Then to hold I drill out the plastic for the other 4 wheels. It is very tight and accurate and is simply turned by 45 degrees or something..

A worn stock distributor where the plastic is loose is much less accurate than my (or other people's) modified ones.

-Rich

[ShelGame]

Look at the HEP its self.

The HEP sensors aren't 180 degrees apart from each other. That means that it is different when not flipped over.

If you don't flip it over and you run it then everything will be off by some degree (probably 10-15 but I didn't measure and this is from memory). Perhaps you can fix that in SW but for guys running stock electronics it would be a problem.

-Rich

---------- Post added at 09:16 AM ---------- Previous post was at 09:08 AM ----------



If you look closely at my picture you can see why it is accurate. It doesn't show well but the shutter holes that don't have rivets in them still slide over the original tabs that I ground the tops off from.

I just grind the tops off from the plastic rivets it leaves 4 tabs on the plastic piece. There are 8 holes in the shutter wheel so you just turn it and push it on over the 4 tabs. Then to hold I drill out the plastic for the other 4 wheels. It is very tight and accurate and is simply turned by 45 degrees or something..

A worn stock distributor where the plastic is loose is much less accurate than my (or other people's) modified ones.

-Rich

Oh, wait - is it actually FLIPPED over? As in top to bottom? I though he was just turning it 180* in the distributor housing. Hmm, I'll have to look at it again. I don't think the HEP needs to be both flipped and have the connectors swapped. Either one should suffice, I think. How do you actually flip it over? Do you dis-assemble the plastic pieces?

As far as the accuracy, it's the '45 degrees or something..' that I think needs to be more accurate. If it's 45* or 50*, it can make a difference in the actual dwell time. Or, conversely, it can possibly causing arcing if the rotor is not in contact when the coil is powered on. I want to calculate what the actual angle should be and what the limits are. It might be OK per Dave's instructions, but I want to confirm for myself.

[bakes]

There is only one other draw back , when making a cam timing change you have to reset the dis timing again . This got Simon and me at the track one night.

[Juggy]

Oh, wait - is it actually FLIPPED over? As in top to bottom? I though he was just turning it 180* in the distributor housing. Hmm, I'll have to look at it again. I don't think the HEP needs to be both flipped and have the connectors swapped. Either one should suffice, I think. How do you actually flip it over? Do you dis-assemble the plastic pieces?

As far as the accuracy, it's the '45 degrees or something..' that I think needs to be more accurate. If it's 45* or 50*, it can make a difference in the actual dwell time. Or, conversely, it can possibly causing arcing if the rotor is not in contact when the coil is powered on. I want to calculate what the actual angle should be and what the limits are. It might be OK per Dave's instructions, but I want to confirm for myself.

you dont flip the hep over. you rotate it 180 degrees. what rich is trying to tell you, is that the pickups on the HEP, ARE NOT 180 DEGREES APART and THEREFORE you have to move the pickup window and flip the connectors.

if you get a hep and take a look at it, you will see for yourself.....example the fuel and spark are approx 150 degrees apart. if you ran the distributor backwards they will now be 210 degrees apart (360 degree full circle...yada yada....)

hope that makes sense

[rbryant]

you dont flip the hep over. you rotate it 180 degrees. what rich is trying to tell you, is that the pickups on the HEP, ARE NOT 180 DEGREES APART and THEREFORE you have to move the pickup window and flip the connectors.

if you get a hep and take a look at it, you will see for yourself.....example the fuel and spark are approx 150 degrees apart. if you ran the distributor backwards they will now be 210 degrees apart (360 degree full circle...yada yada....)

hope that makes sense

Yes that is what I meant. Flipped was a bad choice of words on my part. I just ninja edited it to replace that with "turned 180." Is there a strikethrough font option anywhere on this so I can edit but still show my original word that I wanted to change?

-Rich

[ShelGame]

you dont flip the hep over. you rotate it 180 degrees. what rich is trying to tell you, is that the pickups on the HEP, ARE NOT 180 DEGREES APART and THEREFORE you have to move the pickup window and flip the connectors.

if you get a hep and take a look at it, you will see for yourself.....example the fuel and spark are approx 150 degrees apart. if you ran the distributor backwards they will now be 210 degrees apart (360 degree full circle...yada yada....)

hope that makes sense

I understand that there is an angle difference between the 2 pickups on the plate. What I'm saying is, it doesn't matter if you turn the HEP or the whole freakin' distributor. Plus the cap, they're the only parts that are mechanically connected to each other. The only difference that makes is which plug wire goes into which hole - which is all f'd up for the reverse rotation anyway.

Swapping the connectors is what makes them in the correct sequence again.



---------- Post added at 02:29 PM ---------- Previous post was at 02:28 PM ----------

Yes that is what I meant. Flipped was a bad choice of words on my part. I just ninja edited it to replace that with "turned 180." Is there a strikethrough font option anywhere on this so I can edit but still show my original word that I wanted to change?

-Rich

I wish, couldn't tell you how many times I've needed to take back what I typed...

[rbryant]

I understand that there is an angle difference between the 2 pickups on the plate. What I'm saying is, it doesn't matter if you turn the HEP or the whole freakin' distributor. Plus the cap, they're the only parts that are mechanically connected to each other. The only difference that makes is which plug wire goes into which hole - which is all f'd up for the reverse rotation anyway.

Swapping the connectors is what makes them in the correct sequence again.

Ok I see what you are saying. If you turn the base 180 it is the same thing as turning the plate 180. The base and HEP do however control which cylinder is connected to which spot on the cap because the HEP has a key in it for the cap .

If you don't turn the plate then the #1 on the cap would not be #1 anymore and you could rename the opposite connections on the cap. This could be confusing to some people because many caps only have the #1 labeled and then it would be wrong.

The firing order is 1-3-4-2 so...

In Dave B's setup you rename the cap from:

Stock:

1 3
2 4

to

David B Reverse Rotation:

1 2
3 4



If you didn't turn the HEP and cap it would be:

Stock:

1 3
2 4

to

ShelGame non turned HEP reverse rotation:

4 3
2 1

And of course to run you would have to turn the base 180 degrees instead of the HEP/cap (which is easy to see in the way I numbered them).

So in Software if you just switched pickup #1 and pickup #2 and rearranged the spark plug wires then it should work.

If you got more radical you could also change the firing order to 1-2-4-3 and maintain the stock number on the cap but it might really mess with the balance of the engine given that it wasn't designed for it. This is not an area that I have studied up on.

-Rich

[ShelGame]

Ok I see what you are saying. If you turn the base 180 it is the same thing as turning the plate 180. The base and HEP do however control which cylinder is connected to which spot on the cap because the HEP has a key in it for the cap .

If you don't turn the plate then the #1 on the cap would not be #1 anymore and you could rename the opposite connections on the cap. This could be confusing to some people because many caps only have the #1 labeled and then it would be wrong.

The firing order is 1-3-4-2 so...

In Dave B's setup you rename the cap from:

Stock:

1 3
2 4

to

David B Reverse Rotation:

1 2
3 4



If you didn't turn the HEP and cap it would be:

Stock:

1 3
2 4

to

ShelGame non turned HEP reverse rotation:

4 3
2 1

And of course to run you would have to turn the base 180 degrees instead of the HEP/cap (which is easy to see in the way I numbered them).

So in Software if you just switched pickup #1 and pickup #2 and rearranged the spark plug wires then it should work.

If you got more radical you could also change the firing order to 1-2-4-3 and maintain the stock number on the cap but it might really mess with the balance of the engine given that it wasn't designed for it. This is not an area that I have studied up on.

-Rich

Right. I guess I don't care if i have to re-number each position on the cap. Most of the caps I've seen have all 4 numbered anyway. I was planning to just grind the numbers off and mark it myself.

Actually, swapping the pickups in the code shouldn't be too hard at all. They each have a dedicated interrupt, I just have to switch the interrupt vectors and it would be the same as swapping wires.

The Shutter and Rotor would still need to be re-oriented correctly, though. No way around that one with code.

[ShelGame]

Nevermind what I said about the dwell. The rotor position won't affect dwell. But, if it's out of position by too much, it could affect the total spark duration and cause arcing under the cap. I guess it's not as big a deal as I originally thought it might be.

So, on to figuring out how to re-code the SBEC to swap the ref and sync HEP signals...

[rbryant]

The rotor position won't affect dwell. But, if it's out of position by too much, it could affect the total spark duration and cause arcing under the cap. I guess it's not as big a deal as I originally thought it might be.

The rotor tip and terminals are much wider than required so they should be fine even if slightly off when they need to fire. The shutter can also only be moved at 45 degree angles (it has 8 holes in it) so that should also be very accurate.

-Rich

[turbovanman²]

Nevermind what I said about the dwell. The rotor position won't affect dwell. But, if it's out of position by too much, it could affect the total spark duration and cause arcing under the cap. I guess it's not as big a deal as I originally thought it might be.

So, on to figuring out how to re-code the SBEC to swap the ref and sync HEP signals...

Your a busy guy, so why bother? Its a 20 sec job to mod the connectors,

[ShelGame]

Your a busy guy, so why bother? Its a 20 sec job to mod the connectors,

More fun to tweak the code. Besides, I like confusing you with new source code releases

[turbovanman²]

More fun to tweak the code. Besides, I like confusing you with new source code releases

Gee, thanks,