3.2 Conversion into '72

[Roger 911]

I'll start by apologizing for starting another thread on a 3.2 conversion into an early car. I know there are several very good threads already out there providing a wealth of info on this topic. Unfortunately, as we find out all too often, everyone's situation is usually slightly different. As a result, I find myself with questions that can't seem to be answered perfectly by most of the existing threads. Or, when I search, I just can't seem to find the right threads. Naturally, if anyone can direct me to threads that they think will be of any help, please feel free.

So, now the questions start:

Electrical panel in the engine bay. Can anyone point me towards any info that describes what needs to be done to move from a '72 panel to one that will be compatible with the '84 engine? I read the "Marc's 2.7 to 3.2" thread, but that doesn't seem to be the same as my '72. I know the female 14 pin plug from the engine plugs into the male on the panel, but there are quite a few additional components (relays, regulators, etc) on the '72 panel that do not appear to be on the '84.

Thanks.
Roger

[Flat6pac]

he 14 prong connection on the engine is engine info, oil temp, pressure, key ignition for the starter, back up lights.
The engine is run by the harness for the DME, which gives you coil, tach, everything to run the engine so realize there is 2 systems at work to run the car.
Bruce

[Dodge Man]

IMHO Keep your 72 numbers parts to preserve the value of the vehicle. Get the matching EFI brain & EFI wiring to the brain from the donor car. EFI tends to be a little be happier with the matching brain. I went with 3.0 CIS (carbs work well too) in my 73 because it was the least amount of changes. The 3.2 will bolt up but the trans/ring & pinion will be a concern if you like to hot rod the car. Some people have not had issues but others have sheared 7:31 gear teeth because of the increased torque (not peak HP). A 8:31 915 will handle the torque but will probably require a speedo change. The suspension & tire size will also need to be considered if you want to hot rod around. Is it is a matching numbers car? Is it just better to get a later model Carrera for the 3.2 power? Not passing judgment, just saying. Make yourself happy.

[inaminit]

Roger- Look up the threads and posts by E Sully. I think that his 14 pin plug discussion is the best. You have got to understand where each wire goes and its function, and if you need that particular wire at all. So-get a 72 wiring diagram, an 84 engine bay diagram and an 84 DME engine harness diagram and dig in. Then-draw your own diagram. I bought a set of 14 pin male and female plugs and made a foot long 14 pin extension cord, and was able to make the 14 pin connections that I needed within that cord. You will not need the regulator or the CD box, but you will need the coil.

[Roger 911]

Originally Posted by Flat6pac

he 14 prong connection on the engine is engine info, oil temp, pressure, key ignition for the starter, back up lights.
The engine is run by the harness for the DME, which gives you coil, tach, everything to run the engine so realize there is 2 systems at work to run the car.
Bruce

I wish I could find a quick reference that explains the difference between the two different control panels. The 72 appears to have several more components on it that the 84 does not. I want to determine if I can just leave these connections open, if they are not needed for the 84.

I've seen several threads showing the "before and after", but I can't find any explaining a step by step of what get's connected where.

Thanks.
Roger

[Roger 911]

Originally Posted by inaminit

Roger- Look up the threads and posts by E Sully. I think that his 14 pin plug discussion is the best. You have got to understand where each wire goes and its function, and if you need that particular wire at all. So-get a 72 wiring diagram, an 84 engine bay diagram and an 84 DME engine harness diagram and dig in. Then-draw your own diagram. I bought a set of 14 pin male and female plugs and made a foot long 14 pin extension cord, and was able to make the 14 pin connections that I needed within that cord. You will not need the regulator or the CD box, but you will need the coil.

Thanks. I have seen his name on a few. I'll look for more. Yes, I know I need to compare the wiring diagrams (I hate electrical work!). I have factory manuals for the 72 and a Bentley for an 84, so I should have what I need (I guess I'm being lazy).

[dezzmo]

Roger,

I did this swap several years ago in my 73 and it's not as difficult as you might think.

PM me if you have any questions, I'd be more than happy to help you.

[Roger 911]

Originally Posted by Dodge Man

IMHO Keep your 72 numbers parts to preserve the value of the vehicle. Get the matching EFI brain & EFI wiring to the brain from the donor car. EFI tends to be a little be happier with the matching brain. I went with 3.0 CIS (carbs work well too) in my 73 because it was the least amount of changes. The 3.2 will bolt up but the trans/ring & pinion will be a concern if you like to hot rod the car. Some people have not had issues but others have sheared 7:31 gear teeth because of the increased torque (not peak HP). A 8:31 915 will handle the torque but will probably require a speedo change. The suspension & tire size will also need to be considered if you want to hot rod around. Is it is a matching numbers car? Is it just better to get a later model Carrera for the 3.2 power? Not passing judgment, just saying. Make yourself happy.

All the original stuff is long gone (not a concern for me). I do have the matching DME, harness, and everything else from the donor car, including the 8:31 915 w/LSD. Yes, I changed the speedo to an electric as well. Suspension is good at 21/27 torsions, 19/19 sways, tires are 205/55 and 225/50 on 16" Boxster rims, bunch of other usual suspension mods for DE, bigger brakes, etc. I should be fine in this respect. I just wanted more power with better everyday drive-ability, without draining my kid's college fund!

Roger

[motogman]

I have a 73 with an 86 3.2L and have been doing some work in the engine compartment. Here are some pictures. I will be happy to try to give you more specific answers and track down wiring etc.

These are not great pictures but... more specifics are possible.

[Roger 911]

Originally Posted by motogman

I have a 73 with an 86 3.2L and have been doing some work in the engine compartment. Here are some pictures. I will be happy to try to give you more specific answers and track down wiring etc.

These are not great pictures but... more specifics are possible.

Very nice. It looks like you're using the original panel, is that correct? What are the two silver boxes for on the panel? I was planning to convert over to a 84 panel (I have), but maybe I should just use my 72?

Roger

[Roger 911]

OK, I found an explanation in the Haynes manual with respect to what is on the '72 control panel. It appears I have a Start Enrichment Relay, RPM Transducer, and a Two Stage Rear Window Defrost Relay.

I assume both the Start Enrichment and RPM Transducer would be related to the original MFI and would not be needed now. Any thoughts?

Roger

[dezzmo]

Originally Posted by Roger 911

OK, I found an explanation in the Haynes manual with respect to what is on the '72 control panel. It appears I have a Start Enrichment Relay, RPM Transducer, and a Two Stage Rear Window Defrost Relay.

I assume both the Start Enrichment and RPM Transducer would be related to the original MFI and would not be needed now. Any thoughts?

Roger

Your right Roger, motogman's panel looks just like my setup so just leave the way it is for now.

[Roger 911]

Originally Posted by dezzmo

Your right Roger, motogman's panel looks just like my setup so just leave the way it is for now.

According to the Hayne's manual, that round black relay is the Start Enrichment Relay. At least that is what was supposed to be there originally, unless it was replaced with a different relay?

I noticed the wiring harness from the 84 has a round relay socket in it, that I presume was originally mounted on the control panel. I have not determined what this is for yet.

Roger

[dezzmo]

Originally Posted by Roger 911

According to the Hayne's manual, that round black relay is the Start Enrichment Relay. At least that is what was supposed to be there originally, unless it was replaced with a different relay?

I noticed the wiring harness from the 84 has a round relay socket in it, that I presume was originally mounted on the control panel. I have not determined what this is for yet.

Roger

Can you post a pic of that socket for me? I'm thinking it might be the O2 sensor connection.......

[Roger 911]

Originally Posted by dezzmo

Can you post a pic of that socket for me? I'm thinking it might be the O2 sensor connection.......

Yes, I'll post a pic later when I get home. This socket is the flat round type that snaps into one of the round holes on the base of the control panel, where you plug a relay into it (3 or 5 prong).

Roger

[inaminit]

Roger-Be careful and check the diagrams-that might be the test plug.

[motogman]

In the pictures I posted the two Al boxes on the original panel are the RPM transducer and a rear window defrost relay. I am not 100% sure if they are used.

You were also asking about a flat 5 pin connector - maybe the one shown below by the dist cap. It is not used in my set up nor is a small round 3 pin connector.




By the way... if you still have the engine out and have not yet done so, check the fuel lines. The 3.2L have three lines which are known weak points and are a PITA to replace with the engine in the car .... ask me how I know . (there is another recent thread where I have received several good reference threads on this issue.)

[Roger 911]

Here are some pics. First pic shows my original panel on the left, with RPM Transducer and Rear Defroster Relay still attached. The empty socket is for the Starter Enrichment Relay, which I don't need. I pulled out the harness, intending to install it into the 84 panel, on the right.


This pic shows the end of the Motronic harness, which I believe attaches to the control panel. This socket is the one I'm curious about. I believe it is the same one in Motogman's photo as well. As inaminit noted, maybe this is the test plug, which would go into the round hole on the vertical panel of the 84 control panel?


I should add that I already purchased the replacement O2 connector from a fellow Pelican (can't remember his name now).

Roger

[Roger 911]

Originally Posted by xuztujma

The suspension & tire size will also need to be considered if you want to hot rod around.

I think you may have missed this above...

"Suspension is good at 21/27 torsions, 19/19 sways, tires are 205/55 and 225/50 on 16" Boxster rims, bunch of other usual suspension mods for DE, bigger brakes, etc."

This is more substantial than a stock 3.2 Carrera, and the car will weigh a few hundred pounds less.

Roger

[Roger 911]

OK, learning more. On the 84 panel, the relay next to the Rear Defrost relay is the Heater Fan Blower relay, below.



Bad news is that this puppy costs $300 and my control panel harness is not equipped for it anyway. I do want to use the heater blower, so I need to figure something out.

I know the blower was intended to be activated by a switch attached to the heater lever between the seats. I don't have this now, but was planning to install some sort of switch. I guess my question is, do I really need the relay, or can I just wire a switch that activates the motor directly without a relay?

Roger