Glazedham42

iTrader: (4)

Well, I finally started Rosie for the first time in over a year this weekend. Things actually went really well for the first startup. Only had one small fuel leak, and some tuning to do. The car runs pretty well, even without being in tune. I rebuilt my own carburetor for the first time, and it's giving me some troubles. Here is the background information.

You can see the diagrams that I put together here. That way you know what I did when I rebuilt the carburetor. A picture is worth a thousand words.
https://www.rx7club.com/1st-gen-archive-71/intake-carb-rebuild-how-strip-nikki-down-648376/

I also have attached a picture that shows some of the symptoms I am experiencing with the carb. Here is the fuel delivery setup that I put together:

-Stock fuel pump going through stock fuel filter, into a second Russell fuel filter, to a Holley 1-4 FPR, and into the Nikki.
-Removed all the emissions crap
-Mech secondaries per your directions
-AP mod per your directions

1) When I start the car I have a small fuel leak that appears to be coming from the inlet fuel bolt (numbers 1 and 5 on the carb diagrams). I tightened the crap out of those bolts, new crush washers, and it still has a slow leak. Does the airhorn casting ever crack near that inlet fitting? That is the only thing that I can figure would cause a leak at this point. It is very slow, and just seems to seep up out of nowhere around the fitting. I guess that it could be leaking around the crush washers, but I think it very unlikely since they are all new. I'm suspecting a crack in the casting right now...

2) My second problem comes when I try to adjust my fuel pressure. I can't get it to go any higher than 0.5 psi on my gauge. Could this be attributed to my slow fuel leak? My only guess at this point is that my pump is either too weak, I have a clog in the FPR, or the slow fuel leak is keeping the system from pressurizing up to 3.5 psi. Is there a way that I can test to see if the FPR is causing my problems? It reads at 0.5 psi, but I'm trying to figure out if the pressure problem is coming from the carb or the FPR.

3) Here is the main thing that has me stumped. When I look down the carb the fuel isn't pulsing very hard into the primary venturis. It just sort of drips in at idle. I can't see any fuel going into the front primary OR secondary venturis. It's like the front half of the carburetor is starved for fuel. The back primary and secondary I can see the fuel going into, but again, it's not a very strong puff. Probably because of my low fuel pressure? Additionally, I have fuel dripping into the rear secondary venturi at all times, regardless of linkage position. It is a steady drip-drip-drip-drip as the car idles. Sometimes it will even puddle up on top of the secondary butterfly. This is obviously not right, but I don't know what is causing it.

When I punch the throttle I get a nice shot from the AP squirter nozzles on both primary venturis. It gives a visible, well dispersed shot of gasoline just like you'd expect. I don't know if I have installed a jet or air bleed wrong, or I have some kind of problem with my linkage or AP adjustment or what. I thought that I would give all this info to see if you guys could recommend anything.

Thanks,
Jamie

Kentetsu

Wow, I'll have to chew on all of this info for a bit before I get back to you.

One thing that came to mind about the fpr though, I just wanted to make sure you understood that to increase the pressure, you would tighten the adjuster bolt (not loosen it like you might think). If I think of anything else, I'll get back with you. Good luck Hammy..

Glazedham42

iTrader: (4)

Yeah, I'm adjusting the FPR right. I've tried cranking it all the way in, and all the way out. It never moves from 0.5 psi. I can set that adjuster bolt anywhere in the range and I always get 0.5 psi.

nick812

My holley FPR was going bad and doing the same thing.

Glazedham42

iTrader: (4)

The FPR is brand new, so I'd be really surprised if it is going bad already. I'm thinking that something is either clogged, or I made a mistake during the rebuild, or something needs adjusted? I sent Sterling all this same info, so hopefully he'll show up here, or else email me back...

RECollecter

iTrader: (11)

Check your fuel pump, I had that problem and ended up being my fuel pump was not performing @ 100%

IanS

iTrader: (4)

As far as the drip on the inlet bolt, I have had this same issue before and one time it was that it cracked as you suggested. Another time, the bolt went in crooked and caused it to not seat properly, even though it got tight. As far as the FPR, I would say if you can bypass it or remove it and check the pressure and see if it is reading higher. The dripping in the carb sounds like a stuck needle. I have had this issue many times and for some reason at least for me, it continues to "come back" even if I put new needles and seats in. I have had the best luck with new seat, used needle and the problem will "stay away" for longer with that setup for some reason. These are some things I have experienced and hopefully it will help you out.

Glazedham42

iTrader: (4)

Ian, thanks for those tips. That makes a lot of sense, and I think you may be right. I'll have to dive into the carb and maybe put the old needles back in there. Is there a needle/seat for the primaries and one for the secondaries or is the carb divided in half with one for the front half and one for the back half (one primary and one secondary per needle/seat)?

I'll take the fuel inlets off the carb too and see if I've got a crack in the casting somewhere. I would guess that is the culprit.

I'm still confused about what is causing the problems with the FPR. Could I blow it out with compressed air to make sure it isn't blocked?

Jamie

Glazedham42

iTrader: (4)

Ian, just to be clear which part is actually causing the problem when the needles stick? #25 or #26 or both? I just want to know what I should be checking when I open it up, and what I might want to replace with the old used parts.

IanS

iTrader: (4)

I usually end up running an old 26, and a new 25 but sometimes it works better vice versa.

The needle/seat assemblies are split front-back so one per pri and sec.

Heres my theory on what can cause the cracking. So, you just rebuilt your carb and now the needles are sticking. What do you do? You give the top of the carb a lil smack to "unstick" them. Well, over the course of the break in you have to do it multiple times, and then deflood your engine MULTIPLE TIMES... Really, theres only one good spot to smack, and thats the top of the bolts for the inlet and outlet. Also seems to work best when smacking those for some reason. Over time, the threads get stretched out a bit an now you have a leak. Well, you can simply retighten and now problem is fixed - until next time... After a while, the threads are so stretched that you have to really tighten the **** out of them to where 1 of 2 things will happen. You either crack the top carb piece (air horn?) or the holes simply strip out.

What happens when the needles stick: The needle and seats are brand new and because they are brand new they need to be "broke in". If you look at your old set, you will most likely see a few small grooves, or rub areas. This is where the breaking in part somes into play. Your new stuff doesnt have these (obviously, they are new) so it takes time to wear in these grooves that they want to naturally ride in/against each other. Now they get hung up on each other, and the next thing you know, your eyeing the 16 pound mall in the garage thinking "that'll fix this piece of ****". Although this would make you feel better for a minute, probably not the overall best option. Anyways now Im rambling and getting pissed off at my carb (doing similar things), so I need to go work on the new FC. Good luck man!!!

Edit: SHould also mention that by loosening the bolts with a hammer, and then retightening them with a wrench aobviously deosnt end up working out the best when the crush washers are one time use only. It really sucks sometimes dealing with all the BS. BUT, once it works right and works right for longer than a month you are golden.

Glazedham42

iTrader: (4)

Is a stuck needle the same as when someone says that they have stuck floats? If I remember right, don't the needles hang on the back of those float tabs somehow?

IanS

iTrader: (4)

Yes, that is correct.

Also, if you mistakenly bent the little tab doo-hicky that the float hangs on, this may be what is causing the no fuel in the front half. BE CAREFUL adjusting this though as this is what adjusts your bowl levels. I would measure the rear one (since it seems to be working more right) and adjust the front to the same level. You have to adjust it when they are hanging, not when its all upside down in your hand like you would normally have it, when holding it, in your hand... Yeah that makes sense lol.

Jeff20B

iTrader: (13)

Holley FPRs are hit or miss. Some work ok out of the box. Others seem to have problems. Some people say it's due to burrs inside. I took the top off of mine and moved the ball in and out of its socket. Didn't see any burrs. Put it all back together and suddenly was able to adjust my fuel pressure. Yay for me. Good luck with yours.

Glazedham42

iTrader: (4)

Thanks for the idea Jeff. I'll pop the top off of that thing too and check the operation. So if I'm getting movement in there then the FPR should be doing its job? I can hear the spring inside creaking when I adjust it. I'm not sure if this is good or bad.

Glazedham42

iTrader: (4)

Anybody have a spare Nikki they'd sell me cheap if I need it? I'm really just looking for one to use as parts if I find out that my air horn is cracked and I need some old OEM float needles.

Glazedham42

iTrader: (4)

I just thought that I would update this thread since I seem to have the problem solved. The fuel leak was coming from the fuel rail somewhere. I swapped in another used one, with new crush washers and the problem disappeared. I bypassed the Holley FPR for now, and I'm just running the fuel supply straight into the carb as usual. I'll fight with the FPR after I know that I have the car running properly.

The main problem was that pesky fuel level in the carb. It appears that the float bowls were overfilling and running over into the secondaries. I pulled the needle valves back out and swapped in some different springs. The ones I was using weren't quite the same height for some reason and one of them was sagging pretty bad. I guess it was just worn out.

I also "burnished" the edges of the needle housings as instructed by Sterling. This basically amounts to polishing the corners of the brass housings to smooth them out and prevent sticking. To burnish them, Sterling suggested that I rub the corners with some sort of blunt metal object, like the back of a spoon, or the non-serrated edge of a butter knife. I did this and the edges of the needle housings got very shiny as you would expect.

I reassembled everything and the car was running very nicely. Carb problems solved for now. 10 minutes later the ignition went goofy. I think I blew an ignitor. So I'm on to troubleshooting that now.

Wish me luck,
Jamie