matt_h

Hello there,

I am new to the whole Mazda Rotary scene ,but I am eager to learn all of the Horsepower tricks that can be used on the engine.

I recently acquired a 1985 RX7 with a 12a in it, I have extensively milled ported and modified the existing intake manifold and carb as well as removing all of the smog equip.

I am curious about the water passages that go thru the manifold, are they a crucial part of the cooling system? or can they be blocked off with freeze plugs in the housing behind the manifold.

I have read about people having problems with them leaking and dont want to have to worry about it .

Thanks in advance for advice given

matt_h

mazdaspeedrex

I've got a Mikuni carb and custom manifold and there are no passages in the manifold. It has the indention for the o-rings and I don't have the holes on the motor blocked off. I have had no problems with leaks. I would think you could block off the passages but I don't know how that will affect the stock carb and manifold.

Rx7carl

20mm freeze plugs in the housings work fine. But keep the orings there as insurance if you can. Even the old ones are better than nothing.

Now give it up! lets see pics of your "extensive milling porting and modifying" of the intake and carb. Or at least extensive description.

phooka

O rings? there's O rings? learn something new every day I plugged mine with freeze plugs when I installed my Mikuni.

dale

matt_h

Thank you all for the input.

Regarding RX7Carl's question on my manifold and carb mods, I will try and have some pictures up next week but in the interim here is a brief description of what I have done.

I removed the butterfly from the primary port and milled a grove from the primary port to the secondary port to match the other side.

I then bored the primary port to match the other in size.

I ported the primary and secondary ports where the manifold bolts to the engine to match the size of the engine ports.

I then polished the entire inside of the manifold and removed all the casting flaws and enlarged it where I could to increase the flow.

I have made block off plates and plugs for all of the emissions ports from aluminum plate and brass plugs.

For the carb all I have done to date is the mechanical secondary thing and removal of all the smog junk.

But in the future I hope to enlarge the venturis and change the jetting.

All of the milling, porting and polishing I have done under the assumption that more flow and even flow would increase horsepower and efficiency.

But since this is my first experience with the Mazda rotary engine I am kinda flying blind right now.

After I get it running (I am hoping by Monday or Tuesday) Ill let you all know how it ran.

Thanks again.

matt_h