Arcolithe

To sum my story short: my car is perky, but just not perky enough.

I was expected some brand new feeling. THe carb is fine as long as you drive it under 3.5k or sometimes 4k rpm, but anything above 4k rpm you have to push the throttle peddle down harder so the carb doesn't choke on itself.

But when you do, it easily throttles 5-8k rpm super fast, sounding like a race car (but it could just be my shitty exhaust.)


Now, to tackle the issue I was thinking of downgrading the jets, only to find out that it may not have been too good of an idea.

How important is it to downgrade my carburetor from 600CFM to 500CFM, for a streetported daily driver.

Currently swapped the primary .100 to .095 jets, and the .095 secondary to .077 jets (lowest recommended setting for 500CFM carburetors)


the difference in the jets between primary and secondary doesn't seem much, but I took it around the block and it seemed peppy for now, but can't really push it since I seem to have a major coolant leak somewhere.

Jeff20B

iTrader: (13)

I guess I can add a couple cents to this.

These carbs will never make very good daily drivers due to their fuel slosh issues for being installed 90 degrees from what a V8 would be. Because of this, it always wants to stumble and stall whenever you slow down and turn left, or just slow down. It gets old fast in a daily.

I'd imagine it would be a terrible autocross carb, because of this.

I had plans on using one in a rotary truck. Not anymore. Gonna go hogged Nikki.

As for jetting advice, I have no idea. Never looked into it because the jets seemed ok on a 13B. It's the fuel slosh that always concerned me. Holleys do it too so I'm done with them as well. Good luck.

luiml73

iTrader: (1)

My nikki just arrived today. As soon as I install it, my new RB SP holley will be for sale at a nice discount

The holley runs perfect from idle to redline, but I have decided to not port my spare motor when I rebuild it, so Im going to use the stock nikki.

I'll pm you when the holley is off just incase you want it. Since we both live on the beach, I can deliver it in 10min

wankel=awesome

Should have gotten the 500 AVS with spring loaded needle and seats and adjustable secondary plates...

The AVS is designed to address the faults of the performer, which youre now experiencing...

PS, why 600 cfm? Thats too big even for a brigeport 12A if youre looking to street drive it.

Arcolithe

only one that was readily available.
I think I ordered the 500 CFM something like May 30th and by June 23rd having a 3rd delay order from summitracing and my first from jegs.com, I cancelled both order (was seeing which would come first, and just return or cancel the slower one) and bought the 600CFM.

Apparently I should have waited it out.

should show me the holley while it's on you mean!

nikki was just hard to work with and constantly had one issue or another with it.

Jeff20B

iTrader: (13)

I see. Well, good luck with a Holley or 500 CFM Edelbrock.

Arcolithe

hopefully I can find one looking new for $150.
or just wait until there's some kind of insane sale from autopart store.... which I highly doubt.


600 CFM is running "alright" but I think we enthuasiasts don't ever want to settle for "aright"

Cookboy

iTrader: (10)

And it's never too late to go back to Nikki. She knows where she belongs.

Arcolithe

unless she and the IM sells for $100, I'm going to slowly work on that while playing with the edelbrock.

than depending which gives out worse performance to my liking and use, I'll use either.

but I think the nikki is way more complicated, but I may just buy larger jets and experiment with it.

85rotarypower

I've got some experience with a Edelbrock Performer 600 on a 6 port 13B engine. Besides the issues mentioned above with fuel slosh, it performed great and had smooth power at any throttle position.

A few questions. Did you modify the secondary "transition smoothing" plate counter weights? I can't recall the exact name of this throttle valve looking contraption but I'm pretty sure that solved some of my part throttle richness. If this plate doesn't fully open it chokes off and disturbs the airflow through the secondary venturi's which spoils the fuel metering process, at least that was my take on it. Having such a large carb on a small engine is probably affecting the performance of this throttle valve kinda thing, it relies on air velocity as far as I can tell to open. Its purpose is to smooth the transition when the secondary throttle plates open.

Another thing, how much have you played around with your metering rods and springs? I found a great deal of improvement from changing the metering rods and springs to get the part throttle dialed right in. Changing jets alone isn't going to get this carb tuned properly.

I wish I could remember what exactly I ended up with on my 13B as it resulted in a fairly stable 13-13.5:1 AFR through most of the throttle and RPM range. A little rich down low at times but very driveable for every day use.

Qingdao

iTrader: (3)

Firstly, I'll second, that 600 is too much for a 12A (save for a BP).

Secondly, aside from slosh on turning only; never with decel. I've never had any issues out of my edlebrock on my 6 port 13B. It pulles rightin the middle 13 or so WOT or half up to 9k or more (the tac starts FREAKING out when you go real high). I think before I sell the car I'm gonna crack it open and figure out its tune (I didn't tune it). Because from what I hear of non-Nikki carbs this one has given me no issuses, and I'd like to replicate that.


Maybe with a 500 cfm edelbrock you can acheive great sucsess with a 12A. Its all in the tune.

snivley whiplash

iTrader: (4)

had great luck with side draft carbs, mainly dellarto, way more tuneable and have a great sound at wide open
just my .02 worth

Arcolithe

new to working with cars on this level, so I haven't messed with the metering jets or spring (don't know how to adjust the spring without potentially damaging the carb)

I figured smaller jets alone would reduce richness, but I need an AFR gauge before I make big moves like this.

Will invest into a 500 CFM soon to see how it runs. but I have to find out what to do with the 600 CFM carb right now. hate to see it as a $300 loss for learning experience, but we shall see.

In the meantime while my nikki is off I get to play around with it and look at guides on upgrading the jets and fabricating the air intake for it.