1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Weber 48 IDA worth buying locally for stock 12a?

Thread Tools
 
Search this Thread
 
Old Aug 14, 2025 | 12:33 AM
  #1  
TopGunM2k's Avatar
Thread Starter
TopGunM2k
Tenured Member: 20 Years
Liked
Loved
Community Favorite
 
Joined: Sep 2004
Posts: 323
Likes: 30
From: San Jose, CA
Weber 48 IDA worth buying locally for stock 12a?

Hello Everyone, just as the title is asking. I have the opportunity to pick up a practically brand new Weber 48 IDA setup complete for a 12a stock port along with the aftermarket fuel pump and pressure regulator. The guy put it all on his 12a stock port motor only to come to the conclusion that the setup was not fast enough. He did zero tuning to the carb and said it ran but never took it to get tuned. I visited him at this shop and he now has a LS3 sitting inside of the engine bay of his rx7 -lol. My question to all of you - if i can pick up the setup at a good price - is it worth it? I currently have a bone stock 1983 rx7 that i picked up a month ago. I enjoy the current setup but find myself wanting more power considering my other daily driver is an Rx8 with full performance bolt on's and ecu versatune. From what I read, the 48 ida is better suited for a ported 12a or a 13b 4 port. 20 years ago, I did have a 1st gen with a street ported 13b 4 port and 48 IDA weber that was all done by the local Rotary performance shop that no longer exists. I would basically be installing a 48 IDA with zero knowledge on adjusting the jets, venturi's etc. along with no local rx7 performance shops nearby - or at least one's that would be willing to work on the carb setup.
Reply
Old Aug 14, 2025 | 07:10 AM
  #2  
t_g_farrell's Avatar
Waffles - hmmm good
Tenured Member: 20 Years
Community Favorite
iTrader: (1)
 
Joined: Jul 2004
Posts: 9,250
Likes: 464
From: Lake Wylie, N.C.
If the price is right and you feel confident enough to dive into tuning it, go for it. It will wake up that 12A, especially if you put a RB street port exhaust on it.
Reply
Old Aug 14, 2025 | 08:10 AM
  #3  
j9fd3s's Avatar
Moderator
Community Builder
Liked
Loved
Community Favorite
iTrader: (3)
 
Joined: Mar 2001
Posts: 31,837
Likes: 3,234
From: https://www2.mazda.com/en/100th/
+1 it needs an exhaust to work, and you will want to be tuning it.
https://www.rx7club.com/1st-gen-gene...paper-1145099/
and we are lucky that we have Pierce manifolds close by, its like next day parts
Reply
Old Aug 14, 2025 | 11:16 AM
  #4  
LongDuck's Avatar
84SE-EGI helpy-helperton
Tenured Member: 20 Years
Liked
Loved
Community Favorite
 
Joined: Oct 2002
Posts: 3,584
Likes: 542
From: Phoenix, AZ
I would buy it just to mount to my spare engine sitting on the stand in the garage. Not kidding.

It's a completely different beast compared to the stock carb, but if you understand carbeurators, you miht enjoy tinkering with it. For me, it would just be a display piece, as I'm fully into the EFI world now, having been spoiled. Here's some relevant information;

Reply
Old Aug 15, 2025 | 08:50 AM
  #5  
j9fd3s's Avatar
Moderator
Community Builder
Liked
Loved
Community Favorite
iTrader: (3)
 
Joined: Mar 2001
Posts: 31,837
Likes: 3,234
From: https://www2.mazda.com/en/100th/
that is a good point, EFI is probably cheaper. the Carb isn't so bad, but the jets add up
Reply
Old Aug 15, 2025 | 11:12 AM
  #6  
j_tso's Avatar
Rotary Freak
Tenured Member: 20 Years
Liked
Loved
Community Favorite
iTrader: (2)
 
Joined: Dec 2004
Posts: 1,973
Likes: 400
From: Austin, TX
Carbs will nickel & dime you if you don't know what you're doing. Pierce calls it "tuning with your wallet."
However, you won't have to muck around as much with a new fuel system that EFI requires except for perhaps a higher flowing fuel pump.

EFI will cost more upfront and you won't be able to tune with a screwdriver, but once tuned well it's better than any carb.
Reply
Old Aug 16, 2025 | 08:09 AM
  #7  
peejay's Avatar
Old [Sch|F]ool
Tenured Member: 25 Years
Liked
Loved
Community Favorite
 
Joined: May 2001
Posts: 12,871
Likes: 574
From: Cleveland, Ohio, USA
I have an EFI equipped car. (Well, several, if you count the non RX-7s) I prefer driving my carbureted one, because it's simpler. Also it amuses me to start an engine by just bumping the key instead of crank and crank and crank while the computer figures out what to do. That's why the EFI car still uses a distributor, much to the anger of the Megasquirt community, but that allows much faster starts.

EFI will require some secondary upgrades like a better alternator and re-engineering the chassis wiring (or making an entirely second harness for the EFI) because the stock setup was engineered for a notion that 1v+ voltage drops here and there are okay.

You can bung an EFI fuel pump where the carb pump lives, but it'll cavitate and sometimes stuck air, and life will be short. A sump setup will solve this but now you need two pumps and a sump tank.

Nothing is insurmountable but an IDA is probably cheaper than EFI right now.

Last edited by peejay; Aug 16, 2025 at 08:17 AM.
Reply
Old Aug 16, 2025 | 01:11 PM
  #8  
TopGunM2k's Avatar
Thread Starter
TopGunM2k
Tenured Member: 20 Years
Liked
Loved
Community Favorite
 
Joined: Sep 2004
Posts: 323
Likes: 30
From: San Jose, CA
Thank you guys for the input and info; it's greatly appreciated. I decided to hold off as the guy wanted more than I thought ($1,500). Still a decent deal considering the setup probably would run about $2k+ new but not enough to have me pick it up. Considering my 1983 GSL 12a is completely stock with no performance upgrades other than the coil overs; getting a weber would create a money pit for me. After doing a lot of research, I came to the conclusion that I am satisfied with the current setup and achieving an average of 19MPG compared to my RX8 getting 17 MPG which is my other daily driver. I recall getting 13mpg on the Weber setup I had back in the day when gas was much cheaper. This would turn my daily into a weekend only car which I am not willing to trade in as it's a joy to drive.

Here's racing beat's input on the weber:
Recommended Applications
The Weber carburetor is well suited for a number of Mazda rotary engine applications, including:
12A Street Port Engine
13B Street Port (4-port) Engine
12A Bridge Port
12A Peripheral Port Engine
(We do not recommend this carburetor for us on a 12A stock port engine.)
Reply
Old Aug 16, 2025 | 01:39 PM
  #9  
peejay's Avatar
Old [Sch|F]ool
Tenured Member: 25 Years
Liked
Loved
Community Favorite
 
Joined: May 2001
Posts: 12,871
Likes: 574
From: Cleveland, Ohio, USA
Holy crap, I get 27-30mpg with my Nikki and my bridge port gets 20-25mpg...
Reply
Old Aug 16, 2025 | 01:53 PM
  #10  
LongDuck's Avatar
84SE-EGI helpy-helperton
Tenured Member: 20 Years
Liked
Loved
Community Favorite
 
Joined: Oct 2002
Posts: 3,584
Likes: 542
From: Phoenix, AZ
TopGunM2k - check your PMs when you get a minute, if you would.
Reply
Old Aug 16, 2025 | 09:27 PM
  #11  
TopGunM2k's Avatar
Thread Starter
TopGunM2k
Tenured Member: 20 Years
Liked
Loved
Community Favorite
 
Joined: Sep 2004
Posts: 323
Likes: 30
From: San Jose, CA
Originally Posted by peejay
Holy crap, I get 27-30mpg with my Nikki and my bridge port gets 20-25mpg...

my understanding is that the 84-85 Nikki was updated and gets better MPG compared to the previous ones. My uncle has an 85 12a and he too gets that type of gas mileage. I also believe my Nikki needs a rebuild as the car is a bit hesitant at take off even after doing a full tune up on the engine.
Reply
Old Aug 18, 2025 | 06:34 AM
  #12  
peejay's Avatar
Old [Sch|F]ool
Tenured Member: 25 Years
Liked
Loved
Community Favorite
 
Joined: May 2001
Posts: 12,871
Likes: 574
From: Cleveland, Ohio, USA
I have a '79 carb on the '81 because its idle fuel and air circuitry is so well engineered that I want to honor it. It's one of the few carbs (only one I have seen) where the idle speed is adjusted without altering the throttle position, so the transfer ports/slots are unaffected by idle speed.

I have a complete 48 DHLA setup for the engine, with a Lake Cities manifold, 37mm chokes, bell crank throttle linkage, etc... but I like the design of the SA carb too much.

Last edited by peejay; Aug 18, 2025 at 06:37 AM.
Reply
Old Aug 19, 2025 | 07:37 AM
  #13  
Jeezus's Avatar
Stu-Tron Get Yo Groove On
Tenured Member: 15 Years
iTrader: (5)
 
Joined: Nov 2006
Posts: 8,482
Likes: 31
From: Huntsville AL
I have tuned carbs before, its a big buy-in if you want to get ALL the jets, e-tubes, etc. The more carbs you have the easier it will get to tune.
As soon as I get some pictures, I will be selling my 12a fuel injection setup. Downdraft IDA manifold/ EFIHardware 55-53-50 IDA, MS2, assorted bits that go on the ITB.
Reply
Old Aug 19, 2025 | 09:45 AM
  #14  
t_g_farrell's Avatar
Waffles - hmmm good
Tenured Member: 20 Years
Community Favorite
iTrader: (1)
 
Joined: Jul 2004
Posts: 9,250
Likes: 464
From: Lake Wylie, N.C.
Geez, I just did a trip to ATL from Charlotte with my hogged out nikki and got 24mpg HWY and about 16mpg on the mountain runs. OP probably need to clean out your carb and make sure its adjusted correctly. I too like carbs better than EFI. They are simpler to maintain and tune to my mind. To each his own.

I also have a RB Dellorto 48 DHLA with the RB intake. I plan on using that on a future Renesis swap where no computers will be used, basically a big 6 port keg swap.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
LouisR503
1st Generation Specific (1979-1985)
11
Apr 24, 2020 10:45 PM
urquhartglen
General Rotary Tech Support
10
Oct 26, 2009 05:14 AM
$100T2
1st Generation Specific (1979-1985)
1
Apr 2, 2006 10:59 AM
LetsGO7
1st Generation Specific (1979-1985)
3
May 9, 2003 12:40 AM




All times are GMT -5. The time now is 04:14 PM.