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Fitting new motors to old RX's

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Old 01-31-06 | 06:19 PM
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Originally Posted by Crit
83 and up had electronic ignition on the single dizzy, and 84-85 use a cleaner installation with the ignitors mounted to the side of the dizzy rather than in a separate box, like earlier units.
Sorry for being a pest - I'm just confused as all hell.

This place:

http://www.wankel.net/~krwright/cars...stributor.html

Indicates the '81+ was electronic - can you elaborate on the differences between '81-'82 and '83+?

Thank you... (again )
Old 01-31-06 | 07:48 PM
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S2 cars (81-83.5) are electronic with a remote unit for the ignitors. S3 cars (83.5 - 85) have the ingnitors on the distributor and use it as a heat sink, so there's no need for a remote layout with its own heatsink. It's just a lot cleaner, plus the ignitors (J-109) are more plentiful.

And yes, front covers are almost universally interchangable. There are 4 MAJOR varieties - 68-73 (dual dizzy front-mount), 74-85 (single dizzy front mount), 86-91 (single dizzy, [CAS, really] side mount) and 93+, with a pair of inductive pickups on the pulley and no dizzy provision at all. To clear up the ignition problems, a simple S2 or S3 electronic RX-7 setup would be the easiest way to go.

Last edited by Crit; 01-31-06 at 07:52 PM.
Old 01-31-06 | 08:03 PM
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Thank you so much for that concise reply - that information is so hard to come by on the net.

I'll go see what motor I've got at home, and I know the distributor I've got separately would be an S2.... If nothing else, the front cover I've got gets me started, then it's just finding the right distributor.

Fantastic. Thanks again!
Old 01-31-06 | 08:09 PM
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Originally Posted by Crit
S2 cars (81-83.5) are electronic with a remote unit for the ignitors. S3 cars (83.5 - 85) have the ingnitors on the distributor and use it as a heat sink, so there's no need for a remote layout with its own heatsink. It's just a lot cleaner, plus the ignitors (J-109) are more plentiful.

And yes, front covers are almost universally interchangable. There are 4 MAJOR varieties - 68-73 (dual dizzy front-mount), 74-85 (single dizzy front mount), 86-91 (single dizzy, [CAS, really] side mount) and 93+, with a pair of inductive pickups on the pulley and no dizzy provision at all. To clear up the ignition problems, a simple S2 or S3 electronic RX-7 setup would be the easiest way to go.
1979 are points

1980 are electronic but the igniters are NOT in the distributor. They are in a separate box and from what I read (but I cant confirm it) the signals are reversed. (green and red wires)

81-85 are the same. Again, I read that lthough there is a slight variance between the SE and non-SE. HOWEVER, it didnt notice any difference when I switched back & fort between SE and NON-SE dizzy.
Old 01-31-06 | 08:25 PM
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Very informative. Good read guys.
Old 02-01-06 | 10:35 AM
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I stand corrected. 81 and up it is.
Old 02-01-06 | 12:38 PM
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Originally Posted by Crit
S2 cars (81-83.5) are electronic with a remote unit for the ignitors. S3 cars (83.5 - 85) have the ingnitors on the distributor and use it as a heat sink, so there's no need for a remote layout with its own heatsink. It's just a lot cleaner, plus the ignitors (J-109) are more plentiful.

And yes, front covers are almost universally interchangable. There are 4 MAJOR varieties - 68-73 (dual dizzy front-mount), 74-85 (single dizzy front mount), 86-91 (single dizzy, [CAS, really] side mount) and 93+, with a pair of inductive pickups on the pulley and no dizzy provision at all. To clear up the ignition problems, a simple S2 or S3 electronic RX-7 setup would be the easiest way to go.
So, to swap a 13B into a car that originally had a 12A it's possible to get around the 13B engine mount problem with a 12A cover, right?

I guess I better save the front cover off one of my bad motors.
Old 02-01-06 | 02:04 PM
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Save your 12A mount and slot it. You can then slide the mount 20mm forward in the car and get your 13B in behind it.
Old 02-01-06 | 03:05 PM
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What I was thinking, get a later 13B engine (side mount type) and use a 12A front cover, of which I have an extra. That way, I can use the custom front mount I made to put a 12A in my rotary Spitfire.

Or, is that necessary? (I don't have a later 13B to eyeball at the moment.)
Old 02-01-06 | 03:13 PM
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As promised...
Attached Thumbnails Fitting new motors to old RX's-bottomview1.jpg   Fitting new motors to old RX's-bottomview2.jpg   Fitting new motors to old RX's-clutchslave.jpg   Fitting new motors to old RX's-electronicignition.jpg   Fitting new motors to old RX's-enginemount.jpg  

Old 02-01-06 | 03:16 PM
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max 5 pictures in one post ??
Attached Thumbnails Fitting new motors to old RX's-enginemovedtofront.jpg   Fitting new motors to old RX's-newxmember.jpg   Fitting new motors to old RX's-nospaceforfan.jpg   Fitting new motors to old RX's-rbrx7headeronrx2.jpg   Fitting new motors to old RX's-shifterposition.jpg  

Old 02-01-06 | 03:20 PM
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Have a look at the filename of the picture if you want to know why I took it...
Attached Thumbnails Fitting new motors to old RX's-startermotorclearance.jpg   Fitting new motors to old RX's-trannies1.jpg   Fitting new motors to old RX's-trannies2.jpg   Fitting new motors to old RX's-transmount.jpg   Fitting new motors to old RX's-sidemountxmember.jpg  

Old 02-01-06 | 03:28 PM
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Weird, your tranny mount lines right up. I have an 85 12a in my 72 RX3 and I used the RX3 motor mount, but the tranny mount didnt line up with my 79 smooth case tranny. I had to use flat metal to make a "bracket". Mounting my engine this way left plenty of room for an electric fan, and I used the stock RX3 radiator. I used the 12a oil pan from the 85 engine as well. It all just dropped in. I only had to change the tranny mount to get it to work. I used the starter from the 85 engine too, since the top mount starter wouldnt work anymore.
Old 02-01-06 | 03:43 PM
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My pictures are from my Rx-2, not my Rx-3.
As you can see the Rx-2 tranny mount was slightly modified (holes slotted).
Since that was not enough, I also inversed the 79 rubber tranny mounting block. That block is not 100% vertical so I did win about half an inch there too.

Did you use the original Rx-3 driveshaft ?
Is the shifter position the same as before ?

Last edited by multirotor; 02-01-06 at 03:46 PM.
Old 02-01-06 | 04:00 PM
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On my rx3 I used the T2 transmission and shorten the tail end 4". This way I didnt have to move the motor forward and the shifter is not too close to parking brake. still left me plenty of room in the front for my elecric fan. But I had to fab a new braket for the transmission.
Attached Thumbnails Fitting new motors to old RX's-picture-040.jpg   Fitting new motors to old RX's-picture-041.jpg   Fitting new motors to old RX's-picture-104.jpg   Fitting new motors to old RX's-picture-125.jpg  
Old 02-01-06 | 05:03 PM
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The RX-3's engine compartment has more leg room than a RX-2.
Old 02-01-06 | 05:20 PM
  #42  
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Originally Posted by islandsnow
On my rx3 I used the T2 transmission and shorten the tail end 4". This way I didnt have to move the motor forward and the shifter is not too close to parking brake. still left me plenty of room in the front for my elecric fan. But I had to fab a new braket for the transmission.
Can you explain how you "shortened the tail end" or point me to a link on how this is done? I read the "how to" On cutting the shifter rod, and was completely confused.
Old 02-01-06 | 05:33 PM
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multirotor has the engine pushed foward and islandnow has it in the stock locatoin.I think stock location is better and less work.
Old 02-01-06 | 06:19 PM
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Originally Posted by Jesuscookies
Can you explain how you "shortened the tail end" or point me to a link on how this is done? I read the "how to" On cutting the shifter rod, and was completely confused.
Heres the my original post and it was explained by 13btnos on how its done, I also posted some pictures before and after. Its not that hard to do once you start taking the rear tail apart. What I dont recomend is using a hand drill to drill the new hole for the dowel pin, it has to be perfectly acurate or it will not work. I'll post more pictures later.

https://www.rx7club.com/old-school-other-rotary-63/t2-trany-rx3-479612/
Old 02-02-06 | 08:31 AM
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My engine is forward because I could not find anyone to shorten & balance my drive shaft here in Europe.
I agree it's not the best solution.
Old 02-02-06 | 09:44 AM
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Originally Posted by P-nut
multirotor has the engine pushed foward and islandnow has it in the stock locatoin.I think stock location is better and less work.
there are different ways to install a 13-B engine.
Stock tranny
Notching the front engine mount bracket wil keep the shifter in the original location. If you decide not to notch it, then the engine will move back and tranny mod is required.

81+
Shifter is further back so you will need to modify the shifter hole again and mod tranny mount. To keep it in stock location, then mod the remote shifter as the above posts.

If you dont slot the front bracket, then the engine will move about an inch back. Pay attention in the clutch slave/fork as it may get too close to the firewall and tranny mods are required. In addition, the shifter will get close to the handbrake. With the handbrake, you can mod a 626 handbrake (remove about 2 inches from the middle, re-welded back and shortened the handbrake release rod).

Again, a RX-2 is a different ball game than a RX-3 due to cramp engine bay. For N/A application, moving the engine back is NOT necessary but for turbo, its a must to make room for E-fan/radiator/IC.

I hate long post.
Old 02-02-06 | 10:41 AM
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Originally Posted by multirotor
My pictures are from my Rx-2, not my Rx-3.
As you can see the Rx-2 tranny mount was slightly modified (holes slotted).
Since that was not enough, I also inversed the 79 rubber tranny mounting block. That block is not 100% vertical so I did win about half an inch there too.

Did you use the original Rx-3 driveshaft ?
Is the shifter position the same as before ?
When using a 79 RX7 tranny, I was able to use the stock driveshaft and the shifter was in the same spot, so it all bolted in. I later changed the rear to a Ford 9 inch and had to shorten the driveshaft. Using the stock rear made the motor and tranny a bolt in affair (except for the plate of steel with 4 holes drilled in it for the tranny mount).
Old 02-02-06 | 11:22 AM
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heres what needed to be done to shorten the t2 tail end.

Measure the bolt holes, It is much easier to measure from one end to the other when measuring center hole to center hole ( but you already know it's 4"). Youll need to remove the shifter collar off the shifter shaft, to do this you'll need to remove the access hole on the other side of the housing and align dowel pin towards it, that's the only way it will come out. The third picture shows I shorten the housing and the tube by 4". You then need to move the dowell pin location extactly 4" forward and shorten shaft. Try not to damage the rubber gromett when removing it off the tube you'll need it and make sure the trany is in nuetral when taking the tail end off.

The last picture will give you an idea what exactly needed to be done. Now get to work....
Attached Thumbnails Fitting new motors to old RX's-picture-011.jpg   Fitting new motors to old RX's-picture-013.jpg   Fitting new motors to old RX's-picture-024.jpg   Fitting new motors to old RX's-picture-025.jpg   Fitting new motors to old RX's-picture-030.jpg  

Old 02-02-06 | 11:23 AM
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heres what it look like after
Attached Thumbnails Fitting new motors to old RX's-picture-031.jpg  
Old 02-02-06 | 01:22 PM
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Originally Posted by islandsnow
heres what needed to be done to shorten the t2 tail end.

Measure the bolt holes, It is much easier to measure from one end to the other when measuring center hole to center hole ( but you already know it's 4"). Youll need to remove the shifter collar off the shifter shaft, to do this you'll need to remove the access hole on the other side of the housing and align dowel pin towards it, that's the only way it will come out. The third picture shows I shorten the housing and the tube by 4". You then need to move the dowell pin location extactly 4" forward and shorten shaft. Try not to damage the rubber gromett when removing it off the tube you'll need it and make sure the trany is in nuetral when taking the tail end off.

The last picture will give you an idea what exactly needed to be done. Now get to work....
Great info islandsnow. The other post I read on this made it look harder than chinese algebra.



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