Your gonna have to modify the nikki,and go with a better ignition

 

I assumed that I would... For now I'm going to work on the intake. That will probably take me a few weekends. As far as the direct ignition conversion, I've seen alot of posts that look pretty ghetto in how they do it. I'm pretty apprehensive to start tearing stuff up on that before I even know whats going on. sir revalot mentioned earlier about how his stock Nikki did fine on his J-bridge, so I can't see doing too much at the moment. I mean, I haven't had time to mess with it that much, maybe this is just poor alignment of timing- F/A mixture.

 

Thanks for the input y'all, it's really giving me a better understanding of the issues.

 

Don't believe the hype about stock Nikkis. They have 20mm primary venturis and are too small for stock applications let alone something that needs a lot more air like a BP.

An example of hype not to be believed in is this (keep in mind it is boost related, but you will see my point): bad_83 said that you do not touch the primary circuit of a Nikki when you run boost through it. He claimed he made 300HP and started splitting rear irons, all on a stock venturi Nikki. As you probably can understand, boost changes things, allowing big numbers from tiny carbs, but I can tell you from extensive testing that I will never, ever run a stock 20mm venturi Nikki in anything. For me it's 23mm to 25mm depending on the application, regardless of whether it's for boost or NA, period.

As for my BP idea, the carb in mind is already hogged out and almost ready. The manifold and spacer are almost ready. I'm just in talks with someone right now about a 12A turbo side project with a Nikki - something else I have not done yet, as I've only done turbo 13Bs with Nikkis so far. Oh and one EFI turbo FD 13B in a 1st gen but it was lame so it's coming out and the 12A turbo will go in once it's built and tested.

I could keep typing but long story short, your Nikki needs to get bigger for better BP performance. Otherwise you can keep on believing the hype if you want to.

So take a couple of weekends and study the Nikki stuff I've posted as you mod your intake manifold. And by the way, boost prepped is the same as NA prepped the way I build these carbs. Don't let the term "boost prepped" throw you off the trail. You can throw boost at it or keep it NA and it performs fine either way. No one else out there makes that claim. But I'm not advertising. Far from it. I'm already plenty busy as it is. I want YOU to study and do the work wankel=awesome and I did to our Nikkis, that we are so enamored about. He followed my freely posted instructions on this forum and ended up with a carb that works better than any RB Holleys he's ever tried. Oh and he has yet to try it with direct fire! You could beat him to the punch! After his recent findings, wankel=awesome is now a believer in the upgraded performance available when direct fire ignition is used. I think you'll like it too.

That's something else I will also never use on something I actually intend to drive: stock ignition. I will always use direct fire. It's really that good!

 

I appreciate the input. You have to realize that this project is definitely a side one. I'm working on a BS right now and only rarely get the time to even drive the '7, so it's not a rushed thing. As far as Nikki hype or whatever, I've seen countless posts on either side. Some users say Nikki for life, others say mods only, and still others say trash the Nikki. Honestly at this point it's starting to sound like an opinion battle in this forum. I've been researching about bridgeport applications since before I even had the car, but even still it seems that people are torn about what carb setup to use. I'll look further into it and decide for myself, but your argument for Nikki mods has definitely been noted.

 

Well, the Nikki is a good carb. I'm not saying it's the most ideal for a Bridgeport, but with some work it kicks ***. The weber 48 is a very good option for a bridgey, but the Nikki will outperform it in street driving, idle quality, and ease of use.

 

Noted. I'll port the manifold and return with the results some time next week.

 

Is that from your personal experience coz I never had any issues in street/canyon run with a bridge, 51 IDA, 4 puck clutch, aluminum flywheel and 4.44 gears.

 

All this pro-Weber vs Nikki-speculation makes me want to try a Nikki on a full bridge.

 

I think I can get the Nikki running good enough to support the bridge, otherwise I'll have to get a new carb and that's $$$ I don't have lol. Is anyone on this site brave enough to vouch for a carb that ISN'T a Weber or Holley? I'm interested to see what else is out there and hear what people think.

 

You probably wouldn't notice a really big difference between the 2 unless it was stop a go, or just cruising. Once the engines airflow requirements are met, so long as the fuel gets mixed properly, airflow is airflow, no matter how the engine gets it.

Intake runner length is comparable, total flow is comparable, cornering load resistance is nearly the same...etc.

The 4bbl just gives you a little extra tune ability at the cost of a slightly more complex carb.

 

Its a simple question. Do you have personal experience?

 

What is your exhaust?

Before doing anything... what is your exhaust?

You will not. Will NOT. get any kind of good idle, drivability, or power from a bridge port unless you have a free flowing exhaust system, especially if you are trying to get that with a carburetor. If it is a single exhaust it needs to be well tuned. A long primary exhaust is the easy button, it doesn't seem to be as sensitive.

Also, solid clutch disk? Start collecting spare transmissions, you'll need them.

 

Exhaust is stock from the maf back. Like I said, I'm a poor college student with zero cash. However, I DID port the exhaust wide open, so I think that should be helping, right? I have general carb knowledge, as this is the first carb car I've owned. And yes, solid puck for he win!!

 

Dual 2.25 into a single rb universal muffler, rb presilencer on each pipe. Puck with spring. Dual diapram pressure plate. Loud, yes idling at 1500 rpm. And yes, you are correct, i blew 2 trannies including the one with miata gears. But no regret, its a fun RX-3. A shortened S5 TII tranny will be used on my bridge semipp

 

With what? Running different carburetors on the same engine?

If thats what you mean, yep. I have tried everything except the Dell on my bridgeport 12A.

I have done

1) weber downdraft IDF AND IDA, IDF had 38mm chokes, and the IDA had 42mm chokes. I worked on and drove a friends with NO chokes at all, and it was a fun car, but I didnt own it, so I didnt get to play with it a lot.

2) Weber sidedraft DCOE, in both DCOE 45 and 48 sizes/flavors, great carb, but tuning it was a bitch, never got either of them 100% where I wanted it. Biggest problem with both carbs was tip-in.

3)Holley 4150/4160. I have seriously messed with these more than I'd like to talk about. Its 90% of my experience. I have gotten these better tuned than any other carb, (on a dyno) but were impossible to live with on a day to day. They for whatever reason were never consistent, and even stuff like idle speed was different one day to the next.

4)Nikki (stock AND modified) My most recent experience on stock and BP was a rather large 31mm secondary nikki I built last summer. It is almost identical as Jeff20B's "boost prepped" carbs other than I had to go to an even larger pump nozzle (1.28) and the secondary jets were 170, up from 155. Primary mains were 120.

Set up like jeff20b builds them they run almost like stock on stock port and street port, but when I tried it on my aging pineapple rebuild BP 12A, i may have gone overboard with the venturi sizing, making it a little more finicky. I also had a relatively stock intake manifold (dual plane) from a 79, that I'm wishing I would have hogged out into a plenum area around 25mm open to get crossflow between rotor 1 and 2 for a little extra top end.

In the end, the only real choices for a bridge in my mind (based on how they ran and drove) were the IDA and the Nikki. And my Nikki was far from perfect.

The IDA had a racecast intake mani, which now belongs to another forum member, and 6 years ago I never thought to measure the runner lengths for a real side by side comparison, but they are close to an early 12A intake.

The only real difference between driving both carbs (while the engine was still in a car), was pedal feel. Power and throttle response was slightly in favor of the IDA above 6k RPM, but everywhere below that the Nikki was better. I also think that if I had properly channeled the intake manifold I could have all but mirrored the IDA completely.

Only drawback of my setup with a nikki is that I used a dual plane intake, and it sort of undersized my carb for the application. The Weber was probably too large, which is why it ran the best with a 42mm choke, but hey.

That about sums it up. I have a few other fleeting experiences with webers I didnt actually own, but just helped to get running/started or whatever. But I only ever owned one bridgeport, and only ever had a single IDA.

 

Thanks for the input. Seems like not many BP people have experienced this problem recently. I'm excited to get the intake out and open her up, hopefully that will help. I'm looking at some carbs just for fun. Weber IDA and a Holley. Seems like I'll be saving my $$ for a while if this port and Nikki mod doesn't help. Does anyone know if the stock air cleaner could be modded to fit the Holley? I'm just really curious.

 

Put a stock port engine in the car until you can afford a good exhaust system.

With a high overlap engine, carb tuning STARTS with the exhaust system and in many respects is DEFINED by it.

With a stock type exhaust system, a bridge port engine will make less power than a stock port, along with worse drivability.

The reason why you can't get the carb to run right is because the engine is always choking on its own waste gases because the exhaust system is so restrictive that it is easier for it to blow up into the intake manifold than out the exhaust. Even at WOT. You might be able to tune EFI to work with that mess to salvage some sort of drivability (not a lot, just some) but trying to make a carb work correctly is going to be almost impossible.

 

Yeah I'm looking into a more free flowing exhaust. I want to ramp it up from the stock size. Does anyone have experience with a larger exhaust, say 1/2-1 inch bigger? I would like to do that but can't find a bigger manifold to fit.

 

The pipes are not restrictive, the mufflers are.

 

Yeah but unfortunately I don't have several hundred dollars to throw down and jump on the Racing Beat bandwagon. I could remove the muffler and converters but I don't have anything to put back in its place.

 

By the time you build an exhaust that can survive the bridge you'll probably eclipse the cost if the rb lol

 

Haha there's the dilemma! I'm going to look into possibly welding up my own maf. What's the standard exhaust size for the '7? Is it 1-1/2 or 2?

 

This is truth... the RB system is very cheap for what you get.

I reiterate. It is harsh but it is the reality, since I have been down this road. Put in a stock port or street port engine until you can get a good exhaust system. Hell, all you need are three end housings and not a whole engine. What you have bought is an education. Porting is cheap, supporting parts to work with the porting is where the money is spent. Especially if you want it to be quiet and have good manners, for some value of good manners. (My car may not know which fork is the oyster fork or whatever but it has good manners enough to say 'excuse me' after it burps at the table)

I have a long primary RB system now. I bought it used because I'm cheap. I also spent so much time and money and effort screwing around with trying to make something quiet and free flowing that I could have bought a NEW system from Racing Beat. Some people learn by being tought and some people just have to **** on the electric fence Boku-tte honto baka...

edit - HA! Searching that phrase, Google will accept the feminine "atashi" as a substitute for the male "boku" and give you the correct reference... and this is why one of my cars is named Oktavia... I'm such an idiot

 

Define "very cheap" because the cheapest I see on RB's website is $800, and that is ~$800 more than I have at the moment XD. And "Put in a stock port". As if I have another 12A laying around haha. I wish I did.