Okay guys, I've owned my fb for 6 years now, and I'm finally removing the factory emissions and intake equipment to install the mikuni sidedraft I've always wanted. So far, I have purchased this: https://www.rx7club.com/1st-generati...ntake-1004411/ - Mikuni 44 and intake from wrongwayracing, and I bought the necessary yoohoo belt from Pineapple Racing, as well as a racing beat header. I bought most of the items on the removing your rats nest write-up list found on the FAQ (minus the aluminum block off plate because I won't be using the stock intake obviously) and I'm ready to get my hands dirty. (I hope).

The only thing I don't have is a fuel pump. I did some searching and it looks like everyone with the Mikuni is running 3.5 to 4.5 psi. My friend works at a parts store and suggested a Mr. Gasket pump with a regulator and guage, all of which he sells. Is this adequate, or should I spend the extra coin on the Mallory from Racing Beat? The motor is stock but will be street ported later.

I'm excited to get started and at least wanted to get all the emissions stuff removed tonight, but does anyone see where I might have missed something? My only engine experience is a 2 stroke motorcycle top-end rebuild, so I'll probably have a lot of questions. I'm going to try and take my time and label everything, my only worry is that some of the pictures on the rat's nest write-up leave me a little confused as to what the writers were referring. Any help is greatly appreciated in advance, I promise pictures and hopefully a video when the deed is done!

 

Thats a great intake for a weber sidedraft. Don't lose it The 44 Mikuni will be ok for a stock
port or mild street port but it may run out of steam at the top end. Don't sweat it tho, because
at first it will be a hellava lot better than the stock nikki.

Stay away from the Mr. Gaskest crap. Get a decent FPR (minimally the holley 1-4 psi one) and a
decent fuel pump like Carter or Mallory. The Carter is a bit noisy but is cheaper. Get the pump in
the 6-7 psi range. It will be good for any mods you do later.

Repeat, friends don't let friends buy Mr. Gasket crap.

 

I'm glad these becoming popular but regardless.

1. is your 1st gen EFI or carb'd normally? I would just get an aeromotive FPR that can regulate an EFI system down to 3-5psi range.

2. I run 5psi but I have an s5 streetport 13b

3. piercemanifolds is a great place to get filters and horns, etc.

4. wolf creek racing has good parts as far as jets (popular carb among datsun guys) but the guy isn't very nice or polite to deal with.

5. premix

6. the mr gasket gauge is crap, as well as the rest of the parts go find a hydraulic shop by you and pick up an accurate and inexpensive gauge.

 

The car has the stock nikki currently, I'll look into the carter pump, if isn't much cheaper I'll just get the mallory with the regulator and a gauge. Tonight I got the air pump off, and twisted up the yoohoo belt trying to get it on so I took the first one off (I bought three). I'll try another one tomorrow with hopefully better results. Did the air pump run the OMP? I'll definitely premix, already bought some Castor 927... Do I need to find a gasket for my intake or can I use some kind of sealer from a parts store?

 

Once you get the pump and regulator sorted out then you will proably be faced with an off idle stumble, at least I did when I was sorting out my Mikuni 44 pph setup. The problem was in the accelerator pump circuit. You will need it to deliver the maximun amount of fuel possible immediately upon application of the gas pedal (to the extreme). I had to tweak it quite a bit to get rid of any free play in the linkage and adjust it to give maximum output. Had to adjust it to a different spec than the Mikuni book called for in order to see the improvement. I also had to install a very large accelerator pump jet. I believe that the long intake runner contributes to this issue.

and btw, if no one has mentioned it a wideband 02 sensor will really make tuning much easier. a bit pricey but will save money on unneccessary jet purchases.

 

i'm running the holley regulator and the carter pump and they work but i don't like the way they fit, if i had to do it again i'd buy the walbro external low pressure pump, which should almost fit like stock, and the mallory regulator racing beat sells.

 

aaaand correct pilot jetting, that was alot of my off idle issue.

 

I can get a walbro 255 from a friend new in the box for 50$, even with a regulator is that still way too much pump? Sounds like I'm in for some head scratching tune sessions, but that's the way it goes with side drafts right? What's the price of a wideband? 300 doll-hairs?

 

Don't use a pump for FI systems and try to limit down with a regulator to use with a carb. It
won't work well and will burn up the pump unless you use a return fuel line from the carb or
regulator. Also most regulators that can regulate to the psi for a carb cannot handle the output
from a FI pump. This is why we keep saying Mallory or Carter. I use the Carter 4070 for example.

 

What regulator do you use with the carter? I found that same pump on Jegs for $81, that's probably what I'll go with.

 

I use t he holley 1-4 psi regulator, deadheaded for now. They run like $20 or something like that.

 

81 bucks? the carter i used was like 60. and its very quiet. GP60430 i used the holley low psi regulator as well, it works great until it doesnt lol

 

It may be cheaper but it only flows 30 gph (rated) at 6 psi. Thats barely enough for a stock
nikki and will not keep up with a weber or weber clone carburator. The 4070 flows
72 gph (rated). We all know the psi and gph you will see at the carb will be
measurably less, so choose wisely.

Maybe its not the regulator thats the problem, you may not be getting enough flow at WOT.

 

walbro makes an external low pressure pump, i can't find it right this second, their website sucks, but its 15psi not 60psi.

i tested my 4070 thru the lines and filters and it does about half what its rated at, which is just under Mazda's spec for the P port, so its enough, but there's no margin

 

my stock nikki runs at less than 3 psi? what nikki are you running that you need anywhere near 6 psi? over pressuring the regulator will cause it to fail, thats was what i meant about the Holley FPR ive killed two of those already running that pump. so i think it pumps more than enough. racing beat recommends around 4.5 PSI for a weber... so that pump will work fine at 6 PSI.. just my .02 why not save a buck or two if possible and not overspend on unused PSI youll never need.. IF were talking about a stock ported 12A here which i assume we are.

i never had any problems, at PSI at the carb... but i dont run the stock hard lines, so maybe that has something to do with it... i dont trust 27 year old parts but maybe im just weird...

 

As I said, 6 psi RATED. That means your not going to see 6 psi at the carb.
Theres losses due to turns and diameter of the supply line, filtration and friction.
J9 documented his 72 gph Carter really only flows 30+ gph. Losses. I know for a
fact that with my 4070 I only see about 4.5 psi at the regulator. Losses. Your only
seeing about 4.5 psi and probaly close to half the flow which is barely enough
for a nikki much less the Mikuni we are discussing here.

You saving a buck is fine, just realize your not getting the performance you could
get, but with a stock nikki maybe its not an apparent issue for you. That pump will
fail big time with a large 2 barrel carby.

I don't have a nikki, see my sig for details.

 

not trying to argue here or debate whoevers findings that your referring too im just saying with my own experience. i never had any "loss" to the psi fairies. i have whats called a gauge at my carb, and its pretty accurate at least thats what Re-Speed says.

but as i said im running a SS braided fuel line all the way to the tank with -AN fittings tapped into the pickup. not sure of the Diameter. with a filter before the pump, and before the FPR.

same setup on my rx2 thats ported and i run a mikuni 48. now im not debating that there isnt some "loss", but more than half the PSI? with that thinking youd need a pump that puts out enough pressure to ruin your regulator.

but i digress...

 

Update!

The rat's nest and emissions stuff are gone! However, still struggling with the yoohoo belt, I twisted the second one trying to get it in place, does anyone have any tricks for this? There is just no flex in the belt, I can't get it to go on without corkscrewing down near the lower pulley. I'm thinking about finding a v-belt that flexes more.... Waiting on intake and exhaust gaskets to arrive before I can continue, thanks everyone for the advice!

 

works great for me but then again the FC has a return line. I run a walbro 255lph to this FPR: Aeromotive 13301
Aeromotive 13301 - Aeromotive Universal Bypass Regulators - Overview - SummitRacing.com

I have used a holley blue pump, hated it.

I have used a holley regulator, hated it.

This setup has been working flawlessly for me, but you gotta run a return. I'm not familiar with the FB or SA stock fuel system.

Yoohoo belt is stupid and useless, all they do is slip, just spend the extra money buy the double alt pulley and then buy 2 new belts.

 

Your regulator alone costs more than my fuel pump and regilator Like I said, as
long as you run a return and the regulator can handle the pressure, a Walpro or
any FI pump can work. Yours is setup correctly so it works.

+1 on the double pulleys, the yoohoo belt is a hack and will be unreliable over time.

 

i actually tested my cater pump, installed in the car (with the stock lines/filters) and i'm glad i did. i found the pump installed in the car, actually does about 4.2psi and 30gph, which is way off its 6psi/72gph rating.

since i'm looking for 4.3psi and i think 35gph, i'm fine, and i actually get to ditch the regulator.

the key here being that i KNOW what my fuel system delivers

 

I thought the dual pulley put added stress on the alternator and the yoohoo was the remedy? Perhaps I got them mixed up, I'll gladly get the pulley from re-speed..

 

Updates soon! My intake and exhaust gaskets came in and I'm ordering a dual pulley from racing beat tonight, as soon as payday comes I'll have a fuel pump..

 

What size/part number belt does everyone use with the dual alt pulley? The carb intake and header are all installed, now I just have to hook up all the lines to the carb, set up the fuel pump, and stir up some premix! Making it run and tuning the carb coming soon!

 

i have a mallory fpr with the gslse fuel pump...and hard lines including the return line..it works great...i basically swapped the gslse fuel tank, pump and hard lines...