Ok so i have an 82 rx7 with a very mild port and custom 2inch extractors into a 2 1/2 inch exhaust with 1 resonator and 1 muffler. That is pretty much the limit of mods i have on the car barring suspension but for some reason my car is eating about 15litres per 100kms (thats 15.68 mpg for you guys in the US) as i am from australia. Now ideally i would like to be getting around about 10 L per 100km (25ish mpg) because it shouldnt be eating the petrol like it is (it smells like a bloody boat). So i was looking for some advice on carbs (short of a rebuild because shes my only form of transport) or maybe can you put an NA 13b injection system on the car without too much trouble. Unfortunately thanks to new Aus laws (queensland in particular) i cannot drive a car with an engine bigger than 12a in it in regards to the rotaries so im stuck with trying to make the current engine more effecient, also the engine is only 18000kms or 11184miles since it was rebuilt. i really need help.

Thanks in advance for any help or advice or just for stopping in to say hi.

Thanks James

 

I don't think anyone makes an intake adapter to fit a 13B 6port intake on a 12A, but Tweakit makes one to fit a 13B 4port turbo intake on a 12A. The only problem is you really need a GSL-SE 13B center iron to be able to use 4 injectors like the factory 13B setup. The only other option is to add 2 injectors to the intake somehow. Then you can run a S4 or S5 NA computer, wiring harness, maf, map, crank angle, and sensors.
A simpler (but more costly) option is to run a thottle body with the injectors at the throttle body and a standalone ecu.

Intake adapter http://www.tweakit.net/shop/product_...oducts_id=6313

Throttle Body http://www.tweakit.net/shop/product_...roducts_id=117

Engine management http://www.tweakit.net/shop/product_...roducts_id=117

 

I am sure some real carb guru's(Sterling) will be able to help you with more specific carb questions, but a carb rebuild really should not put your car down for too long. Certainly not as long as trying to go FI.
Just for reference I have similar exhaust and not many mods other than simplification and I consistently get 22mpg in mixed driving. I can achieve 25mpg on a hwy tank. I do not drive conservatively so I am sure much better is attainable.
I would start with a new fuel filter and run a quarter tank of gas with one can of seafoam. See if there is any rust in the filter. Once that is all clear then you can start looking at the carb.

 

Are you running the stock fuel pump? If not, what is your fuel pressure. Other than that it's most likely time for a carb rebuild.

 

thanks for the replys guys its a big help, unfortunately i dont know what fuel pump im running as most of the work to the car was done by the previous owner and he didnt seem to do a good job.. all i know is that the fuel pump ticks constantly.. and hums under very hard acceleration but apart from that i have no idea.. now im fairly new to this so could you guys give me specifics like where to find stuff like the pressure reg. and how to adjust it... i talked to a carby guy today who suggested that the "power circuit" in my carby may be stuck on.. but i have no idea what that does or where abouts it is.. also all the emission control garbage on the carby has been unplugged.. but not all has been removed.. once i get my digicam back ill get some photos up to show you what i mean.

Thanks James

 

I called robert at rotaryshack.com, and they offer a carburetor at a great price that gives everyone that has used it so far 30 plus mpg. Some of their conservative drivers get much much better than that. Great price and they said performance doesn't really suffer either.

 

The only guy on here that has posted info on the carb you are talking about is only getting like 17 MPG. Not sure if he ever got anything better than that.

Here is the thread about it:
https://www.rx7club.com/1st-generation-specific-1979-1985-18/rotary-shack-weber-34-kit-install-848049/

I just wish that someone who has used this carb would post some real world results. So far, nothing, with the exception of above.

 

That stinks Thanks for the link. Robert said that the great majority of his clients running them get 30mpg plus I have never seen anything from rotaryshack that didn't turn out to be great, so hapefully it is just one bad experience. I imagine so. Those guys are great at what they do. Anyhow, it is a cheap easy option and is certainly easier than a FI setup. It is at least worth researching.

 

You can jet the Nikki carb to get close to 40 MPG if you want to.

 

thanks for the posts guys.. it seems i will need a fuel regulator and gauge.. turns out the previous owner left the fuel pump from the 13bt conversion in it.. so shes running way too much pressure.. just a quick question .. what sort of prices am i looking at in aus to get these things.. just started a new job so i have to drive from caboolture to ashgrove everyday.. then drive around .. for those of you in america or anyone who doesnt know those places its like an hour and 10 minutes either way.. so as you can probably guess its costing me an arm and a leg and various other parts (some vitals even) just to get to and from work.

Thanks James