recently acquired a 73 rx2 with the twin dizzy 12a. i want to upgrade the intake manifold/carb and there is a setup on ebay but its for the fb 12a. will this bolt up or are there design differences like in the 13b's?

thanks

 

Im not 100% sure..but im thinking it will work.

Not saying you want a holley but here are some examples of intake compatibility. If you look at the last one on the list it says 71-85.

http://www.racingbeat.com/RX7-1975-1...omponents.html

I was looking at the gaskets, it looks like the center iron has the taller bigger ports in 74+.

I hope this helps.

 

Taller center iron port is 76-80....oops^^^^

Here is some gasket examples.

http://www.mazdatrix.com/c-2.htm

 

thanks for the reply.

 

some more questions..

still talking about the same early 12a engine..

is it possible to run newer 12a housings and/or rotors with the old stuff or is there going to be any issues with ancillary devices or internal interference? my brain says it would be easy to find 3?mm apex seals and a regular 12a rebuild kit instead of trying to source parts (seems very impossible)to rebuild the old boat anchor i have now.

 

My RX2 is using 1973 twin dizzy stock housings, the stock eccentric, and stock iron plates, but it has newer RX7 3mm 12A Rotors, instead of the 6mm rotors. Runs like a champ

 

if your iron plates have rust on from holding water for years then they might not be useful, when I tore down my motor the front plate and the mid plate were pretty badly rotted, I got lucky that I was able to find a front and mid plate in very useful condition.

 

Yeah tomorrow I'm going to pull the engine and tear it down to see what i have to work with. I hope its good and all that crud is just crystallized atf. I've been having decent luck so far.

 

If you are going to use a newer intake system, I am interested in the old one. would you be willing to give/sell it to me?

 

The RB Holley will work.

 

. I'm
pretty sure the 71-73 housings had some tension bolt holes that don't line up with the 1974 and later 12a housings. 1974 thru 85 are all mostly interchangeable. No problem with the rotors though any will work , 3mm seals will last longer. On the intake side I seem to remember the studs below the water ports were slightly in a different spot on the early 12a's too , you may have to re-drill those holes in the manifold.

 

yeah i ended up with a newer 12a. thanks for the reply. there are numerous differences with the 74' change.