Putting a 1985 12a into a 1979 Rx-7

[Zeff]

Hello,

This probably has been discussed before but I couldn't get the search results exactly what I was looking for. I just bought a 1979 RX-7 with a seized motor. Previous owner ran it without oil . I sourced another motor from a wrecker but it is a 12A from a '85 Rx-7. Shouldn't I be able to just drop it in? I found some info that the 12a from '85 does't use the thermal reactor? Would I then have to buy an '85 exhaust and would that fit in the '79 body. Or am I just better off finding an engine from a '79 - '80?

Thanks again!!

[Chud]

She'll drop straight in, it'll have some additional sensors that your S1 dash won't utilise but that won't effect you. Bin any thermal reactor and airpump gear if your state allows it (not sure how strict smog regs are in Pittsburg) and replace with some headers from Racing Beat or the suchlike.Just make sure you use the correct flywheel/clutch combo.

One other thing - the S1 will have a front mount oil cooler whereas the 85 with have a beehive style cooler sat underneath the oil filter. If your front mount doesn't leak then try and use that rather than the beehives that aren't as efficient.

The 85 with have the electronic ignition so you can lose the external ignitor if you wish. If your 85 keg comes with an alternator then make sure you swap the one from the S1 as that'll be an external regulator setup.

Don't worry though, it's all pretty straight forward.

[Zeff]

Thank you! If I buy the exhaust header that fits the '85 12a, would I then buy an aftermarket exhaust system that fits the '85 12a?

[Chud]

Yeah that'll be fine, the undersides are near as dammit identical through from S1 to S3.

[Zeff]

Well, I finally got the '79 12A out of the car and brought home the '85 12A. It looks like there are a few hoses that are not going to get plugged into anything on the car. Also are the throttle cables etc going to work? The carb looks a little different where they connect to the carb on the '85 motor.

Thanks!

[Chud]

Might well be added emissions guff etc, is it deffo a nikki on the '85?

[Zeff]

They look identical for a few minor connections...

Here is a link to the pictures of the carbs.

https://skydrive.live.com/redir?resid=7 ... der%2c.jpg

[Zeff]

After actually doing some research in the manuals (I should have done first), I found out that the extra bit on the then '85 throttle linkage was for cruise control. Theoretically though that '85 rx7 motor with the '85 carb should plug right in to the '79 body. I know there are some modifications for the electronic distributor that need to be made. Also as you mentioned some emissions stuff may be different.

[Zeff]

Well, the motor is in and all hooked up. Got her running, doesn't quite sound right though. Currently it's an open header. I have to get an exhaust system for it. Here is what it sounds like.

http://www.youtube.com/watch?v=2jYsYJEDaMI

Any thing you guys can detect that might be wrong?

Thanks!!

[RamoNZ]

Doesnt sound right for sure.

Did you change the timing at all or is this as it was from the 85? Would be worth checking plugs, leads and coils but the easiest tway to check the motor is to spin it without the leading plugs in it and check for pulsing out the spark plug holes. Get someone to spin it while you cover the holes with your fingers. Good compression will really push out, but sad compression will show itself through a general lack of air movement.