1984 RX7 12A going in a 1973 RX2

krivman65 · 03-19-2012, 11:23 PM

Hey all, I have a '73 RX2 that I am temporarily putting an '84 RX7 motor in. Has anyone ever done this? The car is a very nice original car, so I am planning on rebuilding the original motor when I have the funds. I would like to use the RX2 wiring harness but I am not sure how to do this, since it had two distributors and it will now have one... Does anyone have any thoughts? Also- I have the 5spd tranny that came with the '84 engine. I have a new clutch and the flywheel needs to be resurfaced, but it is all there and I don't need it. If anyone is interested, please let me know! I don't know what it is worth, but I am thinking somewhere around $150...?

Any ideas would be greatly appreciated!

Thanks,

--Chad

surem · 03-20-2012, 08:56 AM

U will need to cut the tranny to fit it in ur car or cut up ur tranny tunnel. Best bet is to find a 79 tranny.

krivman65 · 03-20-2012, 09:30 AM

I am using the original tranny, not the 5spd; it is for sale.

krivman65 · 03-25-2012, 01:58 PM

So, back to the wiring harness- There is a coil/relay setup on Ebay right now out of a '76.
http://www.ebay.com/itm/MAZDA-COSMO-...#ht_500wt_1202
Does anyone know if this would work with the rx7 distributor? I don't want to hack the original harness...

GySgtFrank · 03-27-2012, 08:00 PM

The newer 84 12A is going to be a lot easier to find parts for. The older 12As had different seals, ports were a lot smaller, plates weren't nitrided, and the twin dizzy ignition was more temperamental. Just to mention a few things.

Why do you want to use the original engine? I'd just store it, in case someone wants to restore the car to original sometime. Although I can't forsee them becoming a highly sought after collector car anytime soon. Most of the people that want them would rather have them driveable.

The Factory service manual and wiring diagrams can be found at:

http://foxed.ca/index.php?page=rx7manual

You'll need to review the factory wiring diagrams for the RX2 and the 84 RX7 to see where the differences are at. These are really good diagrams, so it's not like trying to make sense of those Haynes manual pieces of

.

Once you've figured these out, you'll be able to see where you want to make your changes. The newer electronic ignition is a lot easier to deal with than the twin dizzy. You'll also need to wire some of the other functions of the 84 carburetor (power valve, Air Vent solenoid, & coast richer solenoid to a 12V Ign source, see manuals). You can avoid this if you use the original carb/intake from what I hear.

If nothing else you'll learn a lot about the car in the process.

2gslse · 03-27-2012, 08:10 PM

Something to watch out for is the starter location and flywheel offset, does your starter mount on the trans or is it on top of the engine?

krivman65 · 03-28-2012, 11:31 PM

Well I am using the '73 carb, so that shouldn't be an issue. Thanks for the links! The starter mounts on the top- I am using the original tranny, so this shouldn't be an issue. I would eventually like to rebuild the original engine, just because you don't see them... Well for the obvious reasons stated above.

krivman65 · 03-29-2012, 07:46 PM

So... On to a new issue. I went to bolt the automatic up to the "new engine", which had a manual behind it, and the eccentric shaft is different!!!!

Does anybody have any thoughts besides putting the 5spd in the car or switching eccentric shafts? Funny how when you think something is going to be simple...

GySgtFrank · 04-01-2012, 07:22 PM

I was waiting for someone with a little more experience with the old cars to chime in. I'll give my two cents since everyone else seems to be busy. If your car had the twin dizzy's you should have the old rear plate. I don't believe your transmission will bolt up to the engine, but I could be wrong, you'll have to look close. The only other course I can see (as you don't want to go manual) is to find an auto trans from the newer engines which should bolt up to your 84 12A. The flywheel is a two piece unit, a counterweight (you'll need the right one for the 84 12A), and the flexplate, which I believe bolts to the counterweight. If you try to run it with the wrong counterweight it will self destruct from imbalance. Best bet would be to get the trans and counterweight from an 84 12A car (or equivalent). Like I said, I don't have a lot of experience with the early cars, but this is how most were set up.

04-07-2012, 04:48 AM

I apologise, but, in my opinion, you are not right. I suggest it to discuss. Write to me in PM, we will talk.

GySgtFrank · 04-07-2012, 09:43 AM

Quote:

Originally Posted by vefeBeal

I apologise, but, in my opinion, you are not right. I suggest it to discuss. Write to me in PM, we will talk.

vefeBeal, do you think I am wrong or Krivman65? If it's me, you could very well be right, as I have no direct experience tearing down an engine that old.
I can only go by what I was told.
That's why I waited to see if anyone with more hands on experience would answer. No one did and Krivman65 was looking for suggestions and needed an answer.
If you have the experience, please share your opinion. I, for one, am very willing to learn from people that have actually done the work.
I've seen some extremely high quality of work coming from the guys out of Europe and am always interested.

TOOL · 06-24-2013, 01:46 AM

Twin dizzy stuff and single dizzy stuff doesn't really mix guys lol

03-19-2012, 11:23 PM	#1
krivman65 Rotary Fan in Training Join Date: Apr 2011 Location: McPherson, KS iTrader: (0) Posts: 37 Rep Power: 0	1984 RX7 12A going in a 1973 RX2 Hey all, I have a '73 RX2 that I am temporarily putting an '84 RX7 motor in. Has anyone ever done this? The car is a very nice original car, so I am planning on rebuilding the original motor when I have the funds. I would like to use the RX2 wiring harness but I am not sure how to do this, since it had two distributors and it will now have one... Does anyone have any thoughts? Also- I have the 5spd tranny that came with the '84 engine. I have a new clutch and the flywheel needs to be resurfaced, but it is all there and I don't need it. If anyone is interested, please let me know! I don't know what it is worth, but I am thinking somewhere around $150...? Any ideas would be greatly appreciated! Thanks, --Chad

03-27-2012, 08:00 PM	#5
GySgtFrank Professional Stick Poker Join Date: Feb 2011 Location: Stafford, Ks. iTrader: (0) Posts: 1,005 Rep Power: 15	The newer 84 12A is going to be a lot easier to find parts for. The older 12As had different seals, ports were a lot smaller, plates weren't nitrided, and the twin dizzy ignition was more temperamental. Just to mention a few things. Why do you want to use the original engine? I'd just store it, in case someone wants to restore the car to original sometime. Although I can't forsee them becoming a highly sought after collector car anytime soon. Most of the people that want them would rather have them driveable. The Factory service manual and wiring diagrams can be found at: http://foxed.ca/index.php?page=rx7manual You'll need to review the factory wiring diagrams for the RX2 and the 84 RX7 to see where the differences are at. These are really good diagrams, so it's not like trying to make sense of those Haynes manual pieces of . Once you've figured these out, you'll be able to see where you want to make your changes. The newer electronic ignition is a lot easier to deal with than the twin dizzy. You'll also need to wire some of the other functions of the 84 carburetor (power valve, Air Vent solenoid, & coast richer solenoid to a 12V Ign source, see manuals). You can avoid this if you use the original carb/intake from what I hear. If nothing else you'll learn a lot about the car in the process. __________________ 1979 SA22C (parts of one anyway) http://rotarycarclub.com/rotary_foru...ad.php?t=15585 1975 MG Midget (building) http://rotarycarclub.com/rotary_foru...ad.php?t=18681 1988 N/A SE model FC, dead stock and less than 85k on the clock. This one actually runs, so I don't fuck with it.

03-27-2012, 08:10 PM	#6
2gslse Rotary Fanatic Join Date: Apr 2008 Location: front royal va iTrader: (0) Posts: 440 Rep Power: 17	Something to watch out for is the starter location and flywheel offset, does your starter mount on the trans or is it on top of the engine? __________________ ____________________________________________ 1976 Cosmo needing lots of work 1993 Rx-7 410 RWHP single turbo toy 1985 Rx-7 toy/project car 411HP stoplight terror 2001 Dodge ram 4wd.parts hauler 2016 Ram 2500 cause its a hemi 2006 VW TDI commuter __________________________________________ I guarantee there's a pregnant redneck teenager somewhere in a shitty trailer park that thinks "Ebola would be a lovely name for their child"...

04-01-2012, 07:22 PM	#9
GySgtFrank Professional Stick Poker Join Date: Feb 2011 Location: Stafford, Ks. iTrader: (0) Posts: 1,005 Rep Power: 15	I was waiting for someone with a little more experience with the old cars to chime in. I'll give my two cents since everyone else seems to be busy. If your car had the twin dizzy's you should have the old rear plate. I don't believe your transmission will bolt up to the engine, but I could be wrong, you'll have to look close. The only other course I can see (as you don't want to go manual) is to find an auto trans from the newer engines which should bolt up to your 84 12A. The flywheel is a two piece unit, a counterweight (you'll need the right one for the 84 12A), and the flexplate, which I believe bolts to the counterweight. If you try to run it with the wrong counterweight it will self destruct from imbalance. Best bet would be to get the trans and counterweight from an 84 12A car (or equivalent). Like I said, I don't have a lot of experience with the early cars, but this is how most were set up. __________________ 1979 SA22C (parts of one anyway) http://rotarycarclub.com/rotary_foru...ad.php?t=15585 1975 MG Midget (building) http://rotarycarclub.com/rotary_foru...ad.php?t=18681 1988 N/A SE model FC, dead stock and less than 85k on the clock. This one actually runs, so I don't fuck with it.

04-07-2012, 04:48 AM	#10
vefeBeal Guest Posts: n/a	This rather valuable opinion I apologise, but, in my opinion, you are not right. I suggest it to discuss. Write to me in PM, we will talk.

03-20-2012, 08:56 AM	#2
surem Rotary Fan in Training Join Date: Nov 2010 iTrader: (0) Posts: 62 Rep Power: 15	U will need to cut the tranny to fit it in ur car or cut up ur tranny tunnel. Best bet is to find a 79 tranny.

03-20-2012, 09:30 AM	#3
krivman65 Rotary Fan in Training Join Date: Apr 2011 Location: McPherson, KS iTrader: (0) Posts: 37 Rep Power: 0	I am using the original tranny, not the 5spd; it is for sale.

03-25-2012, 01:58 PM	#4
krivman65 Rotary Fan in Training Join Date: Apr 2011 Location: McPherson, KS iTrader: (0) Posts: 37 Rep Power: 0	So, back to the wiring harness- There is a coil/relay setup on Ebay right now out of a '76. http://www.ebay.com/itm/MAZDA-COSMO-...#ht_500wt_1202 Does anyone know if this would work with the rx7 distributor? I don't want to hack the original harness...

03-28-2012, 11:31 PM	#7
krivman65 Rotary Fan in Training Join Date: Apr 2011 Location: McPherson, KS iTrader: (0) Posts: 37 Rep Power: 0	Well I am using the '73 carb, so that shouldn't be an issue. Thanks for the links! The starter mounts on the top- I am using the original tranny, so this shouldn't be an issue. I would eventually like to rebuild the original engine, just because you don't see them... Well for the obvious reasons stated above.

03-29-2012, 07:46 PM	#8
krivman65 Rotary Fan in Training Join Date: Apr 2011 Location: McPherson, KS iTrader: (0) Posts: 37 Rep Power: 0	So... On to a new issue. I went to bolt the automatic up to the "new engine", which had a manual behind it, and the eccentric shaft is different!!!! Does anybody have any thoughts besides putting the 5spd in the car or switching eccentric shafts? Funny how when you think something is going to be simple...

06-24-2013, 01:46 AM	#12
TOOL The Newbie Join Date: Jun 2013 iTrader: (0) Posts: 7 Rep Power: 0	Twin dizzy stuff and single dizzy stuff doesn't really mix guys lol