fishhouse

Hey guys I'm a total noob so hopefully someone can help me out here. Been a looking here for a while as I've done basic stuff but am now having a problem I need some expert advise on.

Little background:
I inherited a 79' from my mother-in-law last year that she purchased when new and has been tossed around between several members of her family since. It was last driven around 2000 and was then stored under an outdoor garage. All-and-all it's in decent shape considering it's age - no major visible rust, etc. She knew I liked to tinker with cars and I've wanted to restore a 78ish Z or Rx-7 for a few years - just never been serious enough to commit. So, she asked me if I'd take it and get it running again.

Again, since I got it last summer I've done the usual first step stuff - as recommended from my research here: plugs, wires, all fluids, filters, dist cap/rotor, belts, removed and cleaned the carb then reinstalled, and cleaned fuel tank (think that's everything so far).

Finally got it to the point where I could try to give it a start this weekend. Amazingly, it fired up almost immediately.

But, my problem is this:

After starting it idles SUPER HIGH - immediately revs up to around 5,000 RPMs and seems to slowly continue to climb. I've only left it on for about 30 seconds at a time. During this it's got a lot of smoke coming out the rear. Seems to be more bluish oil sort of smoke then a sweet white coolant smoke/steam.

I've checked all the obvious hoses and all seem good. Linkage cables seem good. Not that I totally know the difference! Tried adjusting both idle and mixture screws - both with no really noticeable effect one way or another.

Vacuum leak? Something with the carb? Coolant seal? I'm pretty new to all this stuff so any advice on what might be going on would be much appreciated.

tasty danish

iTrader: (5)

this may sound dumb, but have you checked to make sure the throttle plates are actually closed at idle? I know you said you checked the linkage, but how?

Is the throttle cable pulling the butterflies open? I don''t know what else could really do this, but then again my car's injected.

Always check the smallest, stupidest stuff first. good luck!

OneRotor

iTrader: (3)

check your idle screw. I *think* it's under the air cleaner, with the head pointing toward the driver's strut tower.

Kentetsu

To go along with what has already been stated, pull off the air cleaner and look down into the carb throats. Are the throttle plates fully closed (keep in mind that the primary/smaller plates will still be open about 1/16" normally)?

Don't worry about the smoke for now, that is not related to this issue and we probably won't be able to figure it out until the car idles correctly. However, make damn sure that the oil is not overfilled...

.

DivinDriver

iTrader: (15)

Make sure the hot-start assist isn't activating (if it shorts, it can stay pulled in)

Go carefully thru the linkages and cables, make sure nothing is out of place.

Choke cable adjustment is important, too, since the choke pulling in both closes the choke and advances the throttle.

Sterling

Don't adjust ANYTHING!
If the car wasn't put away like that years ago, then the carb didn't just magically adjust itself out of sheer boredom.
You have a cracked hose or a stuck solenoid.

fishhouse

thanks a ton for the responses so far - you guys rock!

something else i should probably mention:

the engine in this was replaced in 82 - not sure if that makes a difference or not as far as what i have.

i mention this because i've been reading several post about vacuum leaks and this infamous Anti-Afterburn hose and where the idle air and mixture screws are that are in different locations then on mine.

fishhouse

i knew you where going to say that.


Ok, so i can't really test leaks the typical way - taking carb cleaner and spraying around the hoses. i mean the engine already sounds like it's going to lift off at 5k-6k RPMs - not sure i'd be able to hear any difference.

that would leave pulling off all the hoses and doing a blow test on them for leaks?

now, my next question is WHICH hoses exactly? are all the non-fuel or coolant lines in the engine bay "vacuum hoses" that might be causing this or just the ones going into the carb?

next, you mention a stuck solenoid. can you explain this more. which are those specifically and is that a repair or replace sort of deal?

thanks again!

fishhouse

i think these are correct. the 4 smaller brass looking plates deep inside the carb are only slightly open - maybe 1/8" (one is marked in red in the attached pic). now the larger single plate is open all the way (marked in green) - is that correct?

blackdeath647

iTrader: (2)

either your throttle is sticking, idle is set extremely high which has to do with a vacuum leak. check your intake gasket, that would probably be your culprit if you haven't checked yet.

fishhouse

is this a gasket directly under the carb - where it mounts?

Der Kraut

Hola,
I'm the guy that was helping Fish this weekend with his car. We checked all the hoses that we could see and checked the linkages. They seemed to move freely with the exception of the choke cable. It seemed to bind but would move if we coaxed it. we got it started using starter fluid though because of the choke.

For some reason I really feel like the choke is stuck open or it could be the intake manifold gasket under the carb. Is there a way to check and see if its stuck open?

fishhouse

another quick question - maybe related:

i've got one lone nipple that i see that has no cap or hose connected to it. is that correct?

it's located just to the rear of the two idle adjust screws. see attached pics (circled in red) - both standing over driver side front wheel. one is zoomed out and another close up.

Kentetsu

Well, Sterling is here now so you're going to be just fine. Do whatever he says. Don't ask any questions, just do it.......

Sterling

The solenoids I was referring to are on the rat's nest.
If there is a vacuum leak, it's happening well below the throttle body to give an idle that high. Generally speaking an idle that high is due to linkage binding, so check that first.
Is ther slack in the throttle cable? While it's running, can you close the throttle by hand any further? (Don't tweeak the thing, just give it a little "help".)
Don't forget to check the secondary throttle shaft to make sure it's not hanging up.

Sterling

Yeah right. That's not pressure.

blackdeath647

iTrader: (2)

gasket between engine and intake manifold. also i believe that nipple shown in those last 2 pics needs to be plugged

Sterling

Yup.

fishhouse

LOL well i'm going to try. he's still talking a bit Greek to me on some of this stuff...so bare with me.

DivinDriver

iTrader: (15)

The four smaller brass-looking plates down inside are your throttle plates, the larger square one up top is the choke plate.

The smaller bores are your primaries, and manage pretty much all of the air-fuel control under idle and light load; the larger ones are your secondaries, and under normal conditions they only open when the engine is under heavy load; they are operated by vacuum unless they have been previously modified.

When the car is just sitting unstarted, the choke plate should be fully open and the lower throttle plates should appear closed (the static openeing on the primaries is only a thousandth of an inch, normally can't even see it.)

When you pull the choke **** out to start the engine, the choke closes most of the way, and the primaries open slightly.

Stirling can check me on this, but your secondaries shouldn't be open at all, and your primaries at idle shouldn't be open enough to see well.

If both primaries and secondaries are open, no wonder it's revving so high.

Trick will be to figure out why.

DivinDriver

iTrader: (15)

That is supposed to be the connection point for the Altitude Compensator, I believe - - a plastic and metal gizmo that screws into the manifold just below and slightly aft of there.

That would be a Big Vacuum Leak if it's not connected or broken off. The plastic part is known to frequently break, especially when the carb is removed/reinstalled, since the hose is shrt, stiff, and a bit of a bastard to get on and off.

Looking to see if I have a decent picture of it.

ADD: You can see just the top of the hose, here.



Here's a good shot of the altitude compensator and the hose that connects to that nipple:

fishhouse

ok, just checked out the throttle plates in more detail. they are in fact closed - both primary and secondary (thank you for that explanation, btw).

also confirmed choke **** does close the choke plate when pulled - when released the **** draws itself back in and the plate opens fully again.

so, sounds like we ruled that possible issue out.

fishhouse

hot damn you might be on to something!!! i noticed that plastic round tip just below the carb and thought it sort of looked like it was broken but wasn't sure - so didn't want to make a big deal of it and mention it.

when i popped the hood for the first time last year there was a small random hose just sitting in the bay. now it makes total sense where it came from - it's this hose you're referring to!

now, it's broken. the plastic nipple is snapped off and stuck up in the hose. see attached pic.

is this a readily available part - is there a specific name for the plastic end piece that's my broken connection point?

DivinDriver

iTrader: (15)

Yes, that's it. That's where they always seem to break, too.

The plastic part, and it's metal base, is called an Altitude Compensator. I've no idea how readily available it may be; I haven't needed one in a lot of years.

You may be able to epoxy the nipple back on it, if the guts are intact. I'll try to get you a photo tonight of what it should look like, whole.

One of the key tricks to putting a stock carb back on an SA is to ease that hose on at the same time you sit the carb on the studs. The hose has to be rigid because of the angle of bend, but it makes getting the carb on and off without busting the AC very hard, until you get the trick of it. I always put just a tiny smear of Hylomar on both fittings, so the hose will slide easier later, but still seal.

Next to getting that left rear nut on the carb tightened right, it's the meanest part of dealing with an unstripped Nikki, IMO.

Be glad you found the little formed hose. They may be hard to get, too.

Kentetsu

Is this part something he could just eliminate? Would it be easier to go that route?