Need some wisdom on my 13b 1st gen swap.
 

What i am looking for is some direction on finishing my swap.First of all i have a freshly rebuilt street ported 4 port 13b with 3mm seals. I am trying to decide what carb setup to go with. My car will be used to go back and forth to work which is about 40 miles a week or so. My prior setup was a stock 12a with a Racing Beat 465 setup and really had no good luck with it.Sometimes it ran good others it did not.I have looked all over the web and seen more people with Webers than anything else.I have heard they are great but a pain to tune beings they are like two seperate carbs, and also they are costly. Second of all is my exhaust choice. Should i go with a Racing Beat race exhaust over a street exhaust? I would like to get the most HP i can for the money i have to spend. Last but not least, what clutch? Stage 1 should be plenty over stock. I will have a budget of about 1500.00 or so give or take. Also, what is the benifits of Glimer Drive? Is it just for show and the sound? Is it worth the 300.00?

I vote for the side draft weber (or Mikuni or Dellorto etc) with the racing beat "road race" exhaust. The twin exhausts is almost a must for a ported motor. It is what I am running with good results. The ported motor really needs a free flowing exhaust. For me there was a learning curve on the carb tuning which led to the accumulation a collection of jets, emulsion tubes etc for experimentation purposes.

I hear that the weber downdraft carbs make more power but are very cold natured, especially for street use in the winter so I would stick with the side draft since its will be a dd.

To assist with the tuning I have ordered a wideband O2 sensor.

The Racing Beat exhaust is called a "streetport" exhaust by them. It has a road race header, a dual pipe center section (each tube has a presilencer), then the muffler has a Y collector and is compatible with a stock '81-'82 car, but flows well enough for a streetported 13B with a supercharger. I think you'll like it.

Get an Exedy stage 1 clutch kit part number 10806. It is 225mm in size, comes with a street strip strength pressure plate, stock clutch disc, pilot bearing, pilot seal, throw out bearing, plastic clutch alignment tool. You can find it at Respeed, Mazdatrix, Atkins etc. Driveability is said to be excellent. I ordered one for my friend's REPU just the other day. Waiting for it get here. Ask kentetsu how he likes his.

You could get a serpentine pulley set from Atkins. Same price, or close. Uses a nice and quiet 6pk serpentine belt, not the expensive cogged belt. Atkins finally makes a '79-'85 old style waterpump pulley (four bolt) for us 1st genners. I just picked one up for my 4 port 13B powered MG Midget last week.

i too have a streetported 4 port 13b, it's out of a 74 rx4. my exhaust is the RB streetport system, minus the dual presilencers. carb is RB setup for streetport(600cfm). clutch is RB street/strip. flywheel is unknown but is lighter than the steel one RB sells, and the counterweight is made into the flywheel. the guy i got it from claimed it was MFR. the clutch setup isn't a good match for it as it will slip when speed shifting. as for the gilmer drive, i here they get annoying after a while.
this vid will give u some idea of how loud it is.
http://i83.photobucket.com/albums/j2...Picture008.jpg

Rxtasy, that one sounds great. All you've got is headers straight back to an rb muffler? I'm going to have to get one of those sometime if so. I've got headers back to the stock muffler and its annoying it sounds like a lawnmower. It also is loud but noise isnt a concern in my area.

Yeah, I don't care for gilmer, unless you're running a clutch fan. lol!

As for the noise, I'd rather have a Camden on it, so the noise is actually adding power instead of stealing it (making noise costs energy after all).

I just realised gilmer is kinda like rice where you have the sound of power ie supercharger, but it's not. That's kinda funny and sad at the same time. No offense to anyone out there reading this that likes gilmer drive systems.

rxtasy3, I've heard those types of really light but sorta stock looking flywheels are MFR. It's one piece of rotary old school trivia I haven't seen in real life... yet.

I have been running an rx4 intake and modded Nikki on a large street port 4-port 13b for years now and have zero complaints. I run an RB race header to 2.5in collector, then 3in back.

How is your performance? What hp do you think you achieved with your setup? Is 220 give or take a respectable guess? What does it cost to mod a Nikki? I have been using the search option but that takes you all over the place and not where i need to be.I went to Webers web site , i guess it was there site and found a 48 ida down draft for 369.95 without intake. This is brand new. I found 1 on Ebay for 600.00 plus shipping that was with intake but used. If i wait around i can find a Racing Beat holley intake used for a good price or buy one new for 230.00. I can buy a reman Holley 650 for 345.00 and have someone or me prep it for a rotary. So realy its a toss up between the two because price will be close.If anyone else on here has a similar set up please chime in and give my your likes and dislikes, vids, or whatever you think could help me decide. Thanks in advance.

What clutch would you get? I would think a stage 1 clutch is more than enough for a streetported N/A daily driver. You don't want one that is too harsh to drive in traffic

Good Luck! A downdraft weber will yield the most peak horsepower and if tuned properly you may yield 180 whp...

Yes, my mind is made up on the clutch. Stage one is all i need. Years ago a friend had a "bronze clutch" and that was a pain to drive, it was no feathering at all but damm it would shit hard and chirp through the gears!:icon_tup:

Wow i guess Racing Beats numbers are WAY off. I was going by there numbers using their parts. Check it out and see what you think.

I could believe 220 HP at the flywheel. With a well-tuned 48 IDA, a 3" exhaust system, and a mild port job on a 6-port engine with the sleeves removed, Hyper4mance2K did 190 WHP.

My .02 cents.

RB Road Race exhaust (for streetport)
Centerforce DF Clutch. Nicer than stock.....with lighter pedal feel. Worth its weight in gold in my opinion.
Any sidedraft carb...weber, dellorto, etc. Dellorto is my choice though!

220 at the fly is not unrealistic with a fresh motor. I would expect in the 180's on the Dyno.....

Thats where they got me, lol but that is still good. Yes my motor is fresh, only about 5 hours on it.

What 3" exhaust? That wouldnt be to big? I need to hear sound of that one please.

the weber is really nice once you get it tuned, it does get expensive as you have to buy the carb plus all the jets and tubes and stuff.

of course you get to buy jets for any carb so i dunno that the weber is any different than a holley.

no matter what you use a wideband, is really helpful.

Im running a 12A with a Monster Judge Ito SP, Weber 48IDA, Stage 1 Clutch, RB flywheel and a 2.50 in exhaust to a Borla muffler. I wish my exhaust was a bit quieter but Im happy.

It's a custom exhaust system. No, not too big unless you like your eardrums. I guess it got quieter when he redid it with a Racing Beat 3" presilencer.

Here's a video of his car:
http://www.youtube.com/watch?v=U0vbPTuvCzs

wOW, I have watched this vid many times on youtube without knowing anything about this car. That thing sounds like it can get noisy real quick, but to me its not to bad.Thanks for posting it. It gives me some kind of direction to go.:icon_tup:

noise is funny. at sevenstock people were telling me how quiet peepers is, yet 12 hours before that my neighbor came across the street and told me it was "loud enough to wake the dead"

if you live in an area where the dead try to sleep in the middle of the day, 3" is a little hard to do....

thanx. yep, basically that's all it is. it originally was the complete streetport system: road race header, dual presilencers, and muffler. i just put dual straight pipes in place of the dual presilencers. i think the rb muffler has a little deeper tone to them than what the stock mufflers do.

yep it looks just like the stock flywheel, all one piece with the counter weight. but bout half the weight. the stock rx4 flywheel was just too heat spotted to suit me and i found a friend that had this one. i had already decided to get a light one and he only wanted $150 for the one he had. but as i mentioned, the clutch setup i'm using worked really good on the stock f/w but not a good match on this one and slips alittle if i speed shift it like at the drag strip. kinda wondering what setup i need for it for when i need a replacement in the future. which could be quite some time since clutches seem to last me for ever.

On my 12a i had a header and 2 1/2 pipe all the way back to a "fart can?" and i was told it was realy load. I was told you could hear me a mile or so away. What i am wondering is how does that 3 inch work for you. I have been told you lose back pressure. Is that so. I dont think i would have the room for a Race header with dual 2 1/2 pipes all the way back. Does your pipe have smooth bends to it to make it work?

I would imagine more than 160 but less than 220. I modded the nikki myself so it only cost my time, it is basically a copy of sterlings magical carbs, just not as clean :). I have driven several RXs with holleys and wasn't pleased with any of them, which is why i went the nikki route.

I really like the RB race header, but I don't know the make of the exhaust I have, it is obviously made for an fb. The pipe is 3in with two presilencers under the car, and a quite large 3in muffler.

I took a quick vid to show you how loud it is (plugs need changed):


http://www.youtube.com/watch?v=Z7jXguM7KxM

Thank you for taking the time to do that. That does not seem to loud at all, i think it sounds just right. Down here i dont have to worry about cops and such. They care more about audio systems than exhaust. I am just trying to figure if i go with the race header will i be able to fit 2 runs of 2 1/2 pipe all the way back or just go with 3" all the way back.

Yes, you lose back-pressure with a 3" exhaust. THIS IS A GOOD THING. Back-pressure is the enemy of performance (if someone tells you otherwise, it's a clue that they don't actually know what they're talking about). What I think you actually want to know is whether you lose too much velocity with 3", and the answer is no, at least not for a 13B. The only drawback is significantly increased noise.

Don't do dual 2.5" pipes. If you want an uncollected system, use dual 2".

it will fit no problem. just run them to the axle, collect them into one, then go over the axle.

Well i was bout 98% set on the Weber 48, i just got off the phone with a buddy and he told me i will have a big problem tunning this thing. He said i would need to get two 02 sensors and have them put into my header and run to widebands to get a proper tune. Is this true? I have searched youtube and this forum with NO luck. I see hundreds of people running Webers but cant find any solid info on there install and setup and how they tune or what they use to tune. I dont want one rotor running to lean than the other or being to rich. I could go with a Holley and be done with it, but i hear Webers are better. If you guys can point me to a good link for some reading that would help. I am a big boy and can read, but also need help understanding.

Well, you can do it that way if you want. But as long as you use the same jets for both rotors, it's not likely that they'd be too far off from each other. Most people just use a single O2 sensor after the collector or in one of the primaries.

Having run both, I like Webers better than Holleys. They're simpler carbs, and it's much easier to change jets. Plus, Webers don't have as much trouble with lateral g-forces. However, Holleys have the advantage of the possibility of having a choke.

I love my weber. The jets are extremely easy to change in minutes and they are very versatile carbs. Only need one O2 sensor unless you are running dual webers.

I have not dealt with a holley.

Why are you so set on running super long primaries? use a race header and a well designed collector. 1 o2 sensor just after the collector. If you want to build a PPort then by all means go with 100" primary header length, but in a SP you aren't going to see appreciable gains.

i want to loose back pressure! mazda has a chart, on a stock 12A you loose like 8hp for every psi of backpressure in the exhaust, for the PP it looses more hp per psi.

mine is the roadrace header into 2x2"x31" L straight thru glasspacks into a collector into a borla. its reasonably quiet the borla is now the obvious weak link, the glass packs made it sound buzzy and tinny.

like i say sound is a little subjective, i think on a real DB meter it would be right around 100, so its like a loud honda or something

the problem tuning the weber is that there is no instructions, and just about everything you read on the internet is wrong, and or conflicting.

the carb itself is simple and very easy to tune. 1 wideband is all that's needed.

PM me with your email, i have a weber tuning guide that makes it really easy

Ahh, the claassic debate on backpressure..........

In general backpressure is bad. PP or forced induction = Backpressure is very bad

N/A application - Backpressure helps torque (to a small extent) but a little is healthy.

Have a 6-port? Better not go 3". You will need the backpressure to open the ports.

High Hp applications, etc, things are different animal, but for a street port-street driven motor, I wouldn't kill myself trying to avoid it. RB factors in some BP for their exhaust. People have criticized them, but hey, they spent a lot on R&D for our cars. Your 2 1/2" pipe is more than enough if you ask me. I'd take the money you would spend on a 3" and buy a nice pre-silencer!

True, 6-port engines use exhaust backpressure to open the auxiliary ports (though it's easy to work around that). However, it is incorrect to say that backpressure increases torque, in any situation. Torque is reduced by backpressure because it prevents the combustion chamber from being properly scavenged. Doesn't matter if it's a stockport or a peripheral port (although the more overlap you have, the more important scavenging becomes). Exhaust gas velocity is the reason we don't build headers with huge primaries, not backpressure. Velocity helps scavenging, backpressure hurts it.

Now, I will grant that things get more complicated when you add a turbo into the mix, but that's an entirely different discussion.

Really the decideing factor on my exhaust choice is if the guy still has his Road Race header when i have the money,I can get the whole deal for pretty cheap, including mid pipes and muffler. If not it has to be all new.I still have my muffler from my 12a set up so i would only need header back. When i first bought my car it had the stock exhaust with the Racing Beat 465 and intake. To be honest it seemed to have more low end pep with that untill i changed to the 2 1/2. I guess it depend also on the bends in the pipe. Sound is not a issue, just worried about achieving the most hp i can get. I am still wondering about tuning the Weber. If i get it new , should i get it from RB? What 02 sensor to i need?

I like, and recommend, the Innovate LC-1.

regardless of the brand, just make sure it's a wide band o2 sensor.

I feel like I should say something. LOL

Didn't I start it for you at 7stock? Thought I did.

hmm, yeah i know i got to fondle it, but i don't recall if you started it or not. if you did start it and i don't remember it can't be that loud....

Something to keep in mind when looking for HP targets is that dyno results vary based on the type of dyno, test conditions, and operator skill/experience. Google "dyno accuracy" and you'll see some articles on the topic. Dyno Jets, for example tend to provide higher HP numbers than Mustangs --> http://s14.zetaboards.com/RaceJax/topic/6611584/1/ (see post #7).

The real test is how well the car accelerates under the conditions that matter to you. The dyno is a good tool for comparative tests on the same car. For example, you change the exhaust and make a dyno pull -- did the numbers increase? The absolute number the dyno provides, however, should be taken as just an "estimate".

That is true. I just would like a rough estimate of what my car will do.Time will tell. I made up my mind and i am going with the Weber 48 with Racing Beat Race header with dual 2 1/4 back and Stage 1 clutch:icon_tup:

pm me with an email, and i'll send you the easy weber tuning guide, it'll actually work for any carb, but it is weber specific

Why would you want to use such big primaries?

What do you mean by big primaries ?:scratch: Are you meaning the Weber 48?

No, you said you want to use 2.25" uncollected exhaust. Why? It's usually not recommended to go larger than about 1.8" ID for a stockport or streetport. Even peripheral ports only want 1.9-2" ID according to Racing Beat's chart. Go too big and you risk killing your torque at the low-end.

If you are thinking about running true duals, be forewarned they sound horrible. :)

the header should just be the 1.75" ID (inside diameter) stuff RB sells. which is 2" O.D. (outside diameter)

the MUFFLERS can be 2.25 though, that is a legal move. the concern with mufflers is flow, and noise absorption, not pipe size.

old school setup is

1. run the RB header, into 2x2 (or 2.25")x 31" long thrush glass packs, http://www.jegs.com/i/Dynomax/289/24...rentProductId= these are straight thru, no louvers. into 2x2.5" rear mufflers of your choice. dynomax makes the super turbo which flows enough.

its actually surprisingly quiet, even on bridge or PP engines. the bridge/PP motor will want the bigger glasspacks, and maybe 2.25" pipe after the header.

When after reading the replys, i remeber when i first bought my car it had the stock exhaust with the Racing Beat carb setup.It would take off like a bat ou of hell, and go sideways in 2nd gear. I put on my header and ran 2 1/2all the way back and it lost that low end power. But up higher rpms it screamed. So from what you guys are saying 2 or 2 1/4 with some kind of muffler in between is what i need? Also duals all the way back wont sound right?

Just collect to a single 2.5", use at least one presilencer and a large-bodied straight-through main muffler. Alternatively, a long-primary system with a presilencer in each primary, again collecting to 2.5". like a clone of the RB "streetport" system. In either case, use only RB .120" wall pipe, especially before the collector. These are setups proven to work well.