yetterben

So i have looked over a lot of stuff, pretty sure i don't have a vacuum leak any where.

Is this from running to rich at idle or to lean? Is this cause of my locked timing at 10L with a 10 split?

Is this to lean at idle.

Car is idling at 1,150 and fluctuates to 1,200

This is on a turbo blow through Nikki.

It will idle lower but just does the same thing with the same 50rpm lope.

I have heard one opinion just wanted some others first!

I dont mind the sound in fact i like it i just want to know why its doing it.

Oh eah its a sa carb and the lower fule mixture screw is 3.5 out if i turn it in .5 it will die. The screw above it seems to have no effect!


http://www.mp3-codes.com/upload/show.php?id=342337

yetterben

let me know if link works!

Roundabout

iTrader: (8)

Link works. I had a stock 84 S that would do that with the choke partially on. Intake obstruction maybe?

yetterben

Negative on the obstruction choke has been removed. Only obstruction is the carb hat and it does it with it off as well.

Would the timing being advanced cause this at idle? The dizzy is locked. Basically i dont really care as long as my motor is not getting harmed.

yetterben

Is this a sign of too advanced or to retarded. Regardless my dizzy is locked and i have to leave it at 10L 0 trailing which is a ten split. So i guess i could adjust it a little too see if thats it but in the end its gotta go back to where its at now.

ZAN_TUNING

iTrader: (1)

check your floats.. one side might be over filling and pushing fuel in and loading up one of the rotors. OR it's possible you have a clogged up jet

it shouldn't sound that way

yetterben

This morning i tried to eliminate all the things that could be wrong. Took gslse-addicts tt box off put ignition back to stock. Lumpy still there. Checked for vacuum leaks, none to be found. adjusted timing no change or mild change. Adjusted big fat screw on carb. This is where it gets interesting. if i back the screw out enough to make the car run at around 1,500 its steady except for a normal stumble here and there. I am assuming cause its no longer using the idle circuit. i screwed that in so car idles at 1,000 now lump still there but not as lopey. Stumbles for a few then idles smooth than back to lumpy and so on and so forth.

No from this it seems like there might be an issue with the idle circuit??????? Car runs an drives just fine no power loss no issues outside of the realm of needing some top end tuning. If this is no major cause for concern screw it i don't feel like ripping apart the carb for a rock solid idle as it dosnt bother me that much.

I also do have some exhaust leaks in the system here and there nothing has be welded yet or set in stone from down pipe back.

FirebirdSlayer666

iTrader: (3)

AFAIK, the bottom adjustment screw is fuel and op adjustment is air. Try matching them up turn for turn and see how that does

Jeff20B

iTrader: (13)

Do you happen to know the size of the 'idle' air jets at the top of the carb? You are looking at the ones adjacent to the primary air bleeds. The common sizes are 150, 160, 170 and 180. If you can't 'tune' out your bad ide, and it's not something else, you might try changing these jet bleed things to a different size. Sterling has gotten good results on certain carbs by installing a spare set of nickel plated 60 secondary air jets in the primary spot.

Be warned that this makes the idle quite a bit richer because it reduces the amount of air that can get in and mix with the fuel. If your idle is already too rich, this would be the wrong direction.

If your carb started with 150, maybe try 180? If I had a spare set I'd send you mine. I'm on the lookout for a set of 150 myself. Maybe I can fill my 180s with solder and redrill?

yetterben

yeah jeff i have 150's i cracked the carb to see if they where plugged but they arent the 60's are clear too. any other jets i should be looking at?

blwfly

iTrader: (4)

hay would you like to post some pics of your setup.

i have actually got near the same problem i think my mixture screw was dirty and i had to advance the timing.

yetterben

there is pics in my build thread you can dig up. I dunno whats causing it. The only other thing i can think of was i did the water treatment threw the brake booster line about a month ago. cant remember if it was doing it then or not. but i would not see how that would have anything to do with just the idle. Car will start right up no matter what and i can adjust the idle down to like 600 if iwant it still just lopes though. If i had a leak i would no think i could get it to idle that low. When the car is cold it does lope more like maybe 100rpms-150rpms when warm its only like a 50-75 variance.

stranger

check the float levels. sounds like a float might be filling up the bowl with too much fuel causing it to flood.

yetterben

i did start the car with the airhorn off and fuel pump off it sprang to life and idled about 1,100 rpms didnt seem to lope but i only let it run for about 5 seconds or so. No exhaust and late here lol. will fill bowls up tomorrow and see how it does. Out side of the floats being out of wack what else would cause it run decent with airhorn off.

with my adjustable fpr i had backed the pressure down before to get the levels to go below half to try and see if it was floats and it was the same deal. Unless there was a tiny spec of **** in the jets i pulled tonight. When i pulled the jets i held tem up to the light and i could see threw them so i blew threw them and screwed them back in. Does the carb suck more air when the airhorn is off? I have also doene my prior testing with and without the carb hat on the carb!

yetterben

ok so i thought about the airhorn thing. i have killed my pump many times with the car running and the idle didnt improve. The car was running fine before so floats just don't go out of wack. HOw does the idle circuit get fuel? I noticed at the bottom of the bowl below jets there is a hole down there there was some crap in there i blew out. Is that where the idle circuit gets it feed?

yetterben

well it does the same thing with the airhorn off. if i set the idle to like 1,300 it sounds normal so i guess thats where its gonna be

tallbozo

iTrader: (5)

I had a crazy idle (which sounded sick) but found out i had a clogged fuel filter. I ran the tank too low and got some crap in the line...

yetterben

Fuel level/flow is not the issue here. If it was it would have showed when i was filling the bowls with the airhorn off and letting it idle. The car runs and drives and boosts just fine its just the idle. i have it set now at 1,300 and its livable just sucks more gas is all.

Jeff20B

iTrader: (13)

The idle circuit might have a chunk of junk in it. Or you still have a vacuum leak that hasn't revealed itself to you yet. Either way the engine must run on the primary circuit from your description.

Do you see gas spurting from the primary venturis while 'idling'? It's not supposed to.

yetterben

negative on the gas squirting. the last know possible leak could be the intake i guess. everything else is fine as i said its weird that i can get the car to idle down to like 600 but its lopes big time down there. Keep in mind as well this is a SA carb

Adjustments on carb are throttle stop screw air idle screw fuel mixture screw!

Jeff20B

iTrader: (13)

Those carbs do tend to run richer at idle because they were intended for thermal reactors which need a richer mixture to keep the fire lit inside. I'm not sure how to set these carbs for a leaner idle because I've never ran one but it might have something to do with the idle air bleed (or 'jet' as Sterling calls them). Sterling once told me that he sometimes has to install 60 air bleeds (nickel plated - always found next to the secondaries but never near the primaries) in the primary idle air position because that is the only way to get the carb to idle right. He cautioned me that the idle will be very rich if I try it.

Wait, your carb was modified for boost, right? Perhaps none of this applies to your situation.

yetterben

correct. i have the car idling right at like 1,200 and it seems good when there is an electrical load it is almost rock solid its weird!

stranger

having the air horn will let the carb suck in more air, thus leaning it out causing it to run better. did you make sure the floats are full of gas? and there could be a little piece of dirt somewhere in your idle circuit or the accelerator pump is bad just above the idle screw.

StumpDrummer

get your fuel lines blown out and see if that helps i had a problem like that a few months back and it cured mine totally

Sterling

That means it's too rich.
Who prepped the Nikki?