Hey all, I am hoping to get some opinions on what carb I should use when I rebuild and streetport my 12A this winter. I am currently in the planning phase for this build but it look like to open up and refresh the engine all I will need is a soft seal kit as the engine puts up pretty impressive compression numbers (at least 100-105 on all faces). I know its hard to tell just by this though and I will know more when I crack it open after storing the car in November.

Anyway, on to the question. I am posting this to find out what car everyone feels would work best as a daily driven carb for a streetported 12A with short primary header into 2 1/4" single piping. I am looking to keep this as daily drivable as possible even into the cooler months before the snow hits.

A local rotorhead (forum name Buggy) has the RB streetport templates which will be the basis for the port job. I may end up opening the ports up a bit more based on research but lets assume for now that the ports will be to the RB templates. The overall goal with this build is to generate decent power while maintaining good drivability. Until I drove Buggy's half bridgeported 13B powered RX-4, I was actually considering this for my 79 but that setup is not at all easily drivable everyday, nor is it neighbor friendly at 7am lol. I have to admit once moving that car was an absolute joy to drive.

The options I am considering are an Edelbrock thunder series 500cfm with automatic choke, RB holley 465 (both these 4 barrels on the RB manifold), Weber 48 IDA or similar, or a Mikuni 44phh or similar sidedraft.

Some may be surprised about the Edelbrock in the list. Well I had pretty good success with a 600cfm performer series carb on my 82 with a 6 port 13B but that was a little too much carb for that engine. It ran quite well and made smooth power once tuned and tuning was very simple on that carb. The biggest mistake I made on that engine was dropping the Edelbrock for a too large Mikuni 50phh2 (was advertised as a 44phh so I bought it). Anyway, back on topic.

I am not a big fan of Holley's due to their seemingly complex design when compared to the Edelbrock, though it is a slightly better size for a streetport 12A I think, so thats why it made the list.

For the IDA, I have a feeling it will be a favorite here but the only reason I consider it is because I have local guys that have tuned them before with good success. The 48IDA I feel might be a bit large and smaller versions are difficult to find. Overall an expensive carb to begin with.

After my failure with the Mikuni in the past, some may be surprised its on the list here. Well sidedraft carbs seem to be pretty good at keeping intake runner lengths long which helps with low end torque and therefore drivability. These can also be found for a decent price.

So please let me know what you think. Any opinions or other advice would be appreciated.

Edit: I should mention that I do plan to track this car occasionally so take this into account when voting and posting opinions.

 

The Holley is a much *simpler* design than the Carter/Edelbrock AVS.

I've never had good luck with getting an AVS to run right. It seems like if they aren't correct out of the box, there's not much you can do for them. Especially if you get heat soak problems... ever see a carb boiling its fuel while the engine is RUNNING? Ugh. The teeny tiny float bowls don't make things better.

In conclusion, I'm going to side with 48DCOE. I've driven a 45DCOE and it felt like a stock Nikki in both drivability and power.

 

Did you consider the twin 36 DCDs?

I have ran the 44 Mikuni and now have the DCDs.

I was finally able to tune out the off idle stumble out of the Mikuni (took some serious tweaking with the AP system) and once that was done it ran very well and you are right makes good power down low, making it very streetable.

To me the DCDs, while a bit rare, are the best bet. I have more power than with the mikuni and with the progressive setup I have been able to tune the primaries for good mileage while keeping the mixture dead on at wide open throttle. By far the best driveability. Learning to syncronize was not that bad, I actually enjoyed the process.

 

After some reading I am heading toward a sidedraft setup. I considered the dual 36dcd setup. Very nice setup but as stated its hard to find. Keep the opinions coming.

 

I wish I had a side draft carb...

I'm sooooo new to these down draft things, and I don't like them too much. I like PIOLET jets, and needle settings!!! LOL

I am of course assuming that side draft car carburators are identical to motorbike carbs.

 

48 IDA.. much cheaper to grab now as repro. keep it choked to 40's .. simple and sweet

 

I like the Dell, has a choke that actually works in cold weather and gives you that grunt you
need down low for streetability. Make sure to get a RB prepared Dell.

 

I've read good thijg about dellortos. Difficult to get but worth it or so I hear. Im still a fan of the edelbrock simply for the fact that I could probably get one up and running for about $300 including carb, tuning kit and intake manifold. Holley seems to go for about similar requiring a rebuild. Mikuni, Dellorto, or Weber carbs with accompanying manifold seem to be around the $600+ mark. I think about a year ago a dual 36dcd setup went for $700 on ebay.

 

I think there is a Dual 36dcd manifold with carbs on ebay right now for the 13b 4 port but they want $1200 or best offer.