Im aware of how dumb this question probly is..
I picked up a 12a off craigslist for next to nothing to just take apart and have fun with, the rotor housings are in near perfect shape. so i've been toying around with the idea of getting it bridgeported and exhaust ported, rebuilding it, and swapping it out for the 12a in my '82 FB.

Im sure im probly gonna need to upgrade the exhaust (might go with RacingBeat),
Would i need to do anything to the carb? im not familiar at all with carb tuning... (both engines have the stock carb)

Thanks for the help!

 

You may not "have" to but your sure going to want to. I definitely suggest a modded Nikki... but seeing as how I may be biased I'll let others chime in.

 

Figuring out what to do with the carb depends on what type of porting you end up doing. If your going with a Bridgeport the stock nikki won't be big enough whether it's modded or not. A weber 48 Ida is what I use others use a holley.

 

I second the 48 IDA. If you must get a Racing Beat exhaust, be sure to get the long-primary version, or you'll choke it. Also, remember all the high RPM stuff like hardened stationary gears, oil mods, etc.

 

the modded nikki's actually come from the IMSA RS series, which was a bridgeport engine with a "stock" carburator. then rotary engineering offered them in the 80's, paul yaw in the 90's, and sterling in the 2000's....

our local high school shop teacher has run a BP/nikki for a few decades, and i've seen his combo. BTW how would you like to go to a high school where they build bridge port rotaries? it exists....

anyways, since the carb is the restriction, his bridge port is small. the KEY is balance here, the carb can't deliver for a port that is too big. he runs an RB road race header into 2x2" pipes and then 2 mufflers at the back, its quiet and low restriction.

stock ignition, stock timing. i'm sure he runs higher oil pressure and a baffle plate, but that might be it. obviously hardened gears and that stuff would be better, but its not needed. apex seals are carbons, but if you were building a street car, you could run iron seals IF you were a good boy and kept the revs down

the carb is modded like sterling/yaw etc, Rx3 floats, removed choke/emissions. i'm not sure Mr C cuts the venturi's bigger or not, but he will rejet. he rejets to find peak power and then sets it richer. its better to loose 2-3hp than the engine...

combo done right should do about 200hp at the wheels, give or take, which should be FUN

 

Good Lord XD i didnt realize all that went into a simple porting procedure....
Thanks a lot for the advice!

 

dude, just keep it simple. unless your building a drag car or a track monster. remember, minor mods make major differences. my personal thoughts:
clean up the casting in the ports with a dremel. do the same to the intake manifold. keep a stock ignition, just tune it up. jet it right with one of those flow meter thingies (it measures CFM to make sure it's flowing evenly. and finally, header and eliminate the smog equip in the exhaust area. final thoughts = 120-130 hp. and fun.

 

its a combination that works together. a street port would be good too, and less sensitive to the exhaust

 

I agree, sometimes the engine that makes the most power is not the most fun to drive, especially on the street, cause typically all that power is in the higher rpms. It can feel pretty weak down low and you spend way more time in the lower rpm range.



2cts....

 

k i am doing a 12a bridgeport and it is not simple bolt on type of thing or cheap for that matter. A bridgy requires all the internals modded for the high rpms and i have spent from $2500 to $3000 between rebuild kit, internals and so on, mind you, this is me doing most of the work such as porting and so on, only sending out what i could not do because of equipment such as resurfacing the irons. I was going with the ida but then got a great deal on itb set up. but yeah from a large streetport to a bridgeport it a big scale up in cost. my suggestion is go with a mild streetport and a modded nikki, and all the nice power goodies as exhaust and such, it keeps the cost down and its still very fun.

 

Thanks for all the help guys!
I finaly got to clean out/off the engine i picked up... the rotor housings are chipped/cracked... so i guess im gonna have to put my little project on hold.. Maybe next winter ill just work with the engine that i have in the car now!

Thank you all so much!!
-TOFUDRIFTER

 

Since TOFU (orginal poster) is putting this project on hold until next winter maybe I'll hijack the thread being I currently have a NA 13B, a Yaw carb, looking for more topend, and ready to build my next motor.

 

I suppose ill post a little update here, and maybe consider a project thread. But for now I'm.planning on doing a street port on the engine I have now, upgrading the carb (among a lot of other things in the car and engine) and then setting her up for sprays! Haha should be crazy fun xD

 

+1

All of my engines have SOMETHING done to them* if nothing else matching the ports to the intake and ports to exhaust. I usually just take the casting flaws out.

The way I look at it Mazda (Honda whoever) spent a lot of R&D money on what works best. Taking it to the extreme is cool, but you'll get less miles out of it.



As for weither or not you'll need to carb tune... YES!! Always with any change the carb should be addressed. With porting your not nessaraly changing the amount of fuel needed; HOWEVER, you are changing the rate at which it needs to be delivered. I'm largly incompotent with these downdraft carbs (I'm a side draft man), BUT I do have a freind that swears by Weber carbs (or Delroto Same difference). There might be a better carb out there but I don't know enough of the brands to tell.






*The Dodge Dakota is ALL FACTORY MOPAR. And it will stay that way, cause it is RELIABLE as the tides.

 

Interesting that this got brought back up.

I'm actually looking into getting a running 12a with a transmission (just for giggles) from someone local here about 30mins away from me. I'd like to streetport it at the least, as a bridgeport is too big for me and I don't have too much money for the build. I know Matt, username "350swapblazer" is close to me and he's doing a huge bridgeport so he might be willing to help me with a smaller port job if we ever get to meet.

I know I read that you had a mishap with the RHD issue in your car TOFU, how is that coming?? You said you're getting ready to spray?

 

Yeahh as much as I wanted to keep it simple I figure why not. Let's go crazy and have some fun! After all, what else are rotaries for!

RHD issue? Unfortunately I dont recall...

 

Do it!

 

port the hell outta that 12a
carb shouldnt be too hard to mod lol

 

Oh I will, I'm not gonna do a Bridgeport cause of the noise and severe lack of any gas mileage. While this is my fub/project/weekend car I do like to drive it to events. But ill probly do some sort of a street port this winter, stockpile some.parts and slap it all together come spring or summer