Don Bike

I've heard that replacing the stock intake on an 85 12a with a 79 or 80 intake will increase airflow. Exactly what kind of modifications do you have to make to the older intake? I've got a stock carb., header and the rat nest is gone. Thanks!

whofarzed

I just recently did this. Just search and you will find what you need. All you have to do is get a piece of aluminum welded on the 79 or 80 intake. This is so as the 85 engine has an air injection port that needs to be blocked. I just bought a 85 gasket and brought it and the 80 manifold to a welder so he could see what had to be done. Also, I blocked everything on the manifold except for the brake booster (this includes acv and cv same as you probably have blocked on your 85( although they are different blockoff plate shapes) if you are not running your air pump). I also used the 80 carb spacer, and I had to cut some of it so the throttle attachment would clear.

Kill No Cone

iTrader: (6)

So Who,
after all of this work with the intake what did you end up with? Did it really help with the power?

whofarzed

I also did sterlings mechanical secondaries and rebuilt my carb at the same time so I am not sure if this on its own makes a big difference. However, my car pulls a lot better in the high rpm's and it backfires a lot less. When I used to have my 85 manifold with the shutter valve hooked up and no rats nest I used to get the biggest backfire and flames. I would rev it and when it got down to 2 000 rpm it would go baaaaam. Once I plugged this on the 85 manifold this did not happen anymore. However, I would get small little pops on deceleration, now I get none.

djmickyg

do all rx-7 back fire and have flames out the exhasut??
mine does it when i gun it then pull of the accelerator quickly.
i just figured it did that because i had to clean out my exhaust with turps to get rid of about 2-3 litere of oil in there, front tring to start my old sh*t engine. and just the turps was buring and flaming out

paposwing14

so who can i go to if i need that welding done to my 79 intake I learned the hard way after I put it on my car iI notice that leak and i switch it back to factory intake now I dont have no e=one to do the welding for my, email me at paposwing14@aol.com