I have a chance to buy an original 12a, but I want to know a couple things about it first. I have an FB with 12A right now. Was considering the RX2 motor for a turbo build. I have a turbo manifold for a 12A but I'm not sure if it will bolt on to an old school 12a. I just want to know the differences between the two. Pros cons etc. I already know there's a difference between the transmissions, but I'm not sure what it is. I have an extra 5spd trans that I could bolt up as long as they will mate. Anyway. Any and all information is appreciated.

 

Run far away from the original 12A! No parts, poor reliability and lack of turbocharging history should be enough to scare you off. If you must go the turbo route find a jdm 12A-Turbo engine or go the 13BT route. From what I remember none of the manifolds from earlier 12As bolt to later etc. my 2c

 

i think the exhaust bolt pattern changed?

the 68-73 engines are not as good as the later engines, but parts are very easy to find, at this point you need to run the later 3mm 12A rotors and carbon seals as the 6mm seals are too hard to find and the rotor housings won't like iron seals.

big enemy with these engines is corrosion, so the rotor housing surface usually looks great, but you need to look by the exhaust port and spark plugs for pinholes.

since you need to use carbon seals this kind of rules out a turbo

if you need early 12A stuff shoot me a PM, i have lots

 

Intake manifold bolt pattern seems to be the same.i had made a adapter plate so I can bolt up 13b turbo II intake to my 85 12a but for ***** and giggles I bolted it up to a 73 12a rx2 engine I have and it bolts up no problem.

Exhaust bolt patten is slightly different,but the major difference would be the rear iron to transmission bolt pattern is different than the 74-85 12a's.

 

I swapped out the dual dizzy front cover to the single dizzy cover

 

The PO swapped the front cover on this one I used to have too.




Here it is after paint.