Jingkun

iTrader: (4)

Ok so a couple years ago I had a Nikki rebuild supposedly somewhat sterling style by CobraStangSVT. I've heard alot of good reports on his work for other members but I've never been able to get the thing running on my car. So I have a few questions.

First when I hook it up same as my original nikki and let the fuel pump run it pisses all the gas out the purge valve and directly into the carb as though I were flooring it constantly. Well I say first and now that I think about it this is the only problem I can get to. Basically I'm wondering if some nikkis have a different fuel in and return line from other nikkis, ie if you're looking at the carb from the driver side if one nikki will have the return on the left and the other nikki would have it on the right. If it helps the new nikki has a different angle to the fuel ports than my stock carb.

2, is that metal round thing just an fpr? If so then is it supposed to be on the return line?

3, I was thinking that with all the gas just free flowing out of the purge if maybe it's because this nikki has the return line on the other side of it from mine, but could there be anything wrong inside the carb that I might be able to check and fix this?

prophetjohn

iTrader: (1)

yes the return line is supposed to have a filter on it. feed line is the one closest to the firewall.
the FSM is your friend on this one. sounds like the carb might not be quite right to me, but im not an expert on nikkis yet.

Jeff20B

iTrader: (13)

2 The metal thing is a one way valve or a restrictor. I can't recall which it is. I actually threw one away yesterday. It is used on the stock system and is usually not needed when you do mods.

3 When you say purge valve, what are you talking about? The purge valve is a black round plastic thing with three nipples on it that sort of works like a PCV valve but it isn't. If you have gas flowing out of it you've got some things hooked up wrong.

Post some pics.

Jingkun

iTrader: (4)

Sorry running on next to no sleep at the moment. I can't remember what its called but it's the nozzle to the left of the fuel lines that, if i remember correctly, when doing a rats nest removal you typically T it with an oil breather to the charcoal canister. And I wanna say they both typically run through the purge valve.

wankel=awesome

That would be the FBV! (Fuel bowl vent) And the nifty valve its connected to is called the FBVS! Or Fuel Bowl Vent Solenoid, which is probably open 100% of the time on a "sterling'd" carb.

If it is overflowing, then your fuel pressure is too high, or floats arent set correctly.

I have one that dribbles fuel out from there on hard corners at mid ohio even with proper fuel pressure at normal float levels. Dropping the float level cures it

Jeff20B

iTrader: (13)

If your carb has factory set float levels, it's best to leave them alone. Problems start happening when people monkey around with the floats. One of my Nikkis is trying to flood itself thanks to a previous owner. The rest are fine because they were factory set and never opened until I rebuilt them last month.

wankel=awesome

Well, the OP has one of the sterling copies, im just assuming something is awry with the floats for fuel to be up that high in the carb to start with... Could be dirt causing one of the needle and seats not to close too, I suppose. I'd start with the basics: check fuel pressure, check float level on the sight glasses.

Jingkun

iTrader: (4)

Ok so the FBV aside since it seems like in the worst case i can probably just T it into the return line and even use that PCV valve thats already on my return line to make sure that each side isn't putting any unnecessary pressure on the other.

So if the floats were adjusted in such a way that the bowls would just be completely full would that make it bleed out of the jets as well? or could that be cause by something else entirely?

I still haven't gotten much of an answer as to the idea if ALL Nikkis are configured so that the fuel intake is on the firewall side and the return is on the radiator side.

To potentially bring an identifier into this, my factory nikki has the fuel rails bent like \*\ when looking from the driver side and the one that was sent to me has them bent like /*/ . With my stock one being an 83 and I have no idea what year the other one came off of. To rephrase my stock carb bends the rails to the firewall and the new one bends them to the radiator.

I guess other potential fix is if one of yall have a Mikuni laying around or some other carb that doesn't get much fuel starvation on turns, and would happen to be will to let go of it lol

Edit: I did just replace the needles valves and seats because I know the ones it shipped to me with were "burnished" and I thought well if they were burnished too much then the floats wont stop the fuel flow anyway. My fuel pressure is at least good enough for my car to run right now with my factory carb. Idk if the pressure changed from year to year with different nikkis, which is kinda why I'm bringing up the direction of my fuel "rails" as a potential identifier. Not gonna lie I'm pretty carb stupid so outside of those rails these nikkis look identical to me. If you have a list or a link to a list of physical differences I could pick out between the carbs then by all means if you think it will help diagnose the problem. I have tried to adjust the float levels in such a way that it would flood the carb and also in a way where it would be almost dry and I'm still getting the "full throttle effect" as well as the vent flow.

Edit2: god sleep is amazing

Jeff20B

iTrader: (13)

Here is a quick thing to check. The float bowl vent solenoid as wankel=awesome mentioned. Do you still have one and is the wire hooked up to 12V+ when the key and thus the fuel pump are ON? This can easily cause fuel to gush out of places it's not supposed to when not powered.

Jeff20B

iTrader: (13)

As for the direction of the Nikki fuel lines, perhaps the guy who built your modded one is dyslexic, or the carb was previously installed in a car that had its fuel lines going the other direction.

Post some pics. I want to see this thing.

wankel=awesome

+1 on posting pics too, a picture is worth a thousand words. In this case probably several diagnosis' as well haha.

Jingkun

iTrader: (4)

Ok pics coming up. I just need to ford the river of my apartment complex and brave this rain and I'll be right back.

Jingkun

iTrader: (4)

Thats all the pics I took. I'm not sure if I was wrong or if I bent the fuel rails toward the fire wall since it made for a really awkward fuel line position. I did see some plier marks on the rails so I think I bent them.

I guess another question is with the rats nest delete how necessary is the spacer plate since I'm not using any of the vac bungs on it?

Jeff20B

iTrader: (13)

I can give you some good news. The fuel lines are pointing the correct direction at least. The paint scheme though? Puke worthy. Glad I don't paint my carbs. That looks like ***.

So, what was actually done to this thing? Did the guy hog out the venturis at all? Did he trim or thin the throttle shafts? Any jetting and air bleed tuning performed? I'm starting to doubt it at this point. Looks like a ham fisted approach to Nikki mods.

I can see some glaring omissions. He didn't touch the accel pump, did he. The vacuum secondary housing is still installed, so probably doesn't have mechanical secondaries. It's also missing a throttle return spring and the bracket. Looks like a 79 throttle lever, not a correct FB style (but I do like the 79 style a bit better due to its simplicty but the FB type works well enough).

Over all, without knowing anything else about the carb and just seeing the pictures, I'd rate this carb very poor on the modded Nikki scale, where Yaw and Sterling are up near the perfect 10 range. Kentetsu's Sterling would be a perfect 10 for example while others vary as some had unsolvable idle problems etc. He races it and it does awesome and runs perfectly. I hope you didn't have to pay very much for your red and black thing.

Yeah, I see the plier marks too. Why are they there is my main question about that. There is no reason at all the grab the tube with pliers like that.

As for the phenolic carb spacer, it is a good idea to keep. Just block off all five nipples with short pieces of vacuum hose and a piece of a broken drill bit (not the twisting drill part but the round shaft) shoved in. Or anything the will prevent a vacuum leak. The phenolic material is a heat insulator. I somehow doubt you've blocked off your ACV port and/or the coolant ports in the engine which let heat into the manifold. You also have long studs that will run out of threads before the nuts are contacting the cast iron carb base.

Jingkun

iTrader: (4)

I can always replace the nuts, if the acv port is that thing I had to shove jbweld into to block it off then that is gone, but so far my attempt at freeze plugging the coolant ports has been a failure.

$400 is what I paid. Vac housing is still there so I can always switch between the vac and manual secondaries but it is currently set for manual. The return spring and bracket are on the bottom of the cart I took the pictures on. I'm fairly certain he honed out the venturis, and that throttle lever is the same as what is on my stock 83 carb mind that this has been stripped of choke and everything that isn't the pedal and idle control.

Here is a link to the thread with all the stuff he was doing in it https://www.rx7club.com/1st-generati...update-972809/

Supposedly all that paint on the carb was supposed to be powder coated on but I'm pretty sure based on the fact that its just flaking off that its rattle canned.

Jeff20B

iTrader: (13)

400 and it doesn't run right?

Can you take a pic down into the carb so we can see the work he did? I should be able to tell whether he hogged the venturis or not just from a picture.

wankel=awesome

Naw, that looks like powder coat. It does flake, if not fired (baked) correctly.

Jeff20B

iTrader: (13)

That does look like an FB throttle lever after all. I wasn't looking at it too closely as I was blinded by the powder coating.

Too bad it's powder coated. That makes it much harder to remove while leaving the underlying metal intact.

Wow, I realize I'm being very negative, which I'm sure is not helping you. I'll try something positive. I'd like to see a picture down through the top of the carb so I can offer some encouragement.

wankel=awesome

Pretty sure thats just a stripped Nikki with minor mods, as I think the guy that sold you that one was building legal carbs for some type of racing class. I remember his posts, because he was restricted to the vac secondaries, and I have always liked the vac secondaries so I tried to buy one too lol

Arcolithe

this guy worked wonders when I posted pics of my rebuild.

obvious things like "hey that's not X but is actually Y"

which made me feel very derpy, but now my nikki is running (and my edelbrock is coming in june 5th =))

Jingkun

iTrader: (4)

Yeah I'm about to head into work, I'll nab some pics and get them uploaded when I get to work. Don't worry about being negative, it usually winds up being more constructive I think.

Jingkun

iTrader: (4)

Hope that works



Also with this last picture, does any of this denote the idea of mech secondaries?

wankel=awesome

Well the good news is, it DOES have some visible airflow mods. Cant tell exactly how extensive without studying it really closely alongside a stock nikki in terms of booster size and acc pump nozzle size.


Still looks like a vac secondary carb to me too, btw.

Jeff20B

iTrader: (13)

My take on it is stock size secondary venturis with reprofiled cut, and booster mods. The primaries are harder to see but they look reprofiled too with booster mods. He did a straight cut on the supports instead of the more time consuming but better flowing angled cut. He must have started doing them in batches and needed to speed up production. I was tempted to do this myself, but didn't. As for primary venturi size, I can't see in there well enough to guess accurately but maybe 22mm.

I don't like the retracted OMP tubes. Why? Because it makes that part of the carb oily and the oil gets down, soaks into the base gasket then seeps out and starts to collect dust and debris. The carb is a dust and dirt magnet now making it ugly years sooner than a stocker. Of course with that color scheme, the job was accomplished before assembly heheh.

Think of it this way. When you enlarge the venturis, is a little OMP nipple tube really that much of a restriction anymore? I think not. You also miss out on some engineering Mazda did when they had them in as far in as they did (about a razor blade's thickness away from the booster). Having them close lets more oil get into the engine more effectivly. Having them far out like yours lets the oil kind of go where ever it wants. It will run down the venturis and you'll get really oily throttle shafts too now I suspect.

We can't see the accel pump nozzle holes or the business end of the banjo bolt, but having looked at that guy's thread link you posted, I'm sure he drilled them out. Couldn't tell you what size, but if he followed Sterling to a T, he used a .050" drill bit. Might be a bit large for your application. They looked really big in the pictures.

Looking at the other picture, looks like Sterling's flip-o-matic that the svt guy was messing around with. So yes I'd say that picture does denote mechanical secondaries.

Oh yeah one more thing. He did the Sterling Holley jet mod on the air bleeds. That's cool... but you'll need a selection of these jets or air bleeds to do any tuning. I prefer to use stock air bleeds and swap them around until the desired tune is achieved. You can only go so far up or down in size anyway.

Jingkun

iTrader: (4)

Well all that is cool and all, but I pulled my omp a long time ago so no worries about the oil drip and it still doesn't tell me why its pissing gas out the jets without any throttle. None of yall would happen to know anyone near Austin that knows a lick about these things would you? Just that it would probably be easier than me parting the carb down, taking pics of everything, and then putting it back together wrong.