Tiny hesitation on bottom end.
02-28-09, 08:32 PM
#1
Tiny hesitation on bottom end.
I'm having a small blip or hesitation at the bottom of each gear change. It kinda sounds like the engine is coughing... If you can picture that. Ot's not enough to stall the engine. It does'nt always happen, but when it does happen it is noticeable. It doesn't matter if you are over or under 2000 RPM. It seems to NOT do it when the choke is pulled out halfway.
Suggestions?
I've played with the timing and it doesn't matter where I set it at. I've played with the idle mixture, doesn't affect it. I've adjusted the TPS looking thing on the front of the carb and no change. I have also played with the accelerator pump a bit and didn't notice a change.
What else could it be? The car drives great other than the little blip here and there. Cruises smooth. Has plenty of power.
My old Nikki (79 model) did this too except it would buck when cruising at 55 MPH. Is it just how I have something hooked up that could be wrong?
Could I need a new dizzy rotor?
-79 engine with an 83 Nikki.
-Emissions removed.
-Vacuum secondaries.
-br8eq stock plugs.
-Pacesetter header to a stock exhaust.
-Holley blue fuel pump set at 4.5 PSI (Racing Beat recommended pressure).
-Racing Beat carb hat.
-Idles at 800 RPM.
-Vacuum advance is plugged into the 2nd to the left nipple on the carb spacer.
-Crank case and float bowl vents?? are plugged into the 2 nipples nearest the mixture screw. (Is this correct??) As stated in the emissions removal by Carl. Everything else is capped with an ACV block off plate with gasket.
Suggestions?
I've played with the timing and it doesn't matter where I set it at. I've played with the idle mixture, doesn't affect it. I've adjusted the TPS looking thing on the front of the carb and no change. I have also played with the accelerator pump a bit and didn't notice a change.
What else could it be? The car drives great other than the little blip here and there. Cruises smooth. Has plenty of power.
My old Nikki (79 model) did this too except it would buck when cruising at 55 MPH. Is it just how I have something hooked up that could be wrong?
Could I need a new dizzy rotor?
-79 engine with an 83 Nikki.
-Emissions removed.
-Vacuum secondaries.
-br8eq stock plugs.
-Pacesetter header to a stock exhaust.
-Holley blue fuel pump set at 4.5 PSI (Racing Beat recommended pressure).
-Racing Beat carb hat.
-Idles at 800 RPM.
-Vacuum advance is plugged into the 2nd to the left nipple on the carb spacer.
-Crank case and float bowl vents?? are plugged into the 2 nipples nearest the mixture screw. (Is this correct??) As stated in the emissions removal by Carl. Everything else is capped with an ACV block off plate with gasket.
03-01-09, 09:12 AM
#2
Nikki-Modder Rex-Rodder
Join Date: Feb 2001
Location: Trying to convince some clown not to put a Holley 600 on his 12a.
Posts: 2,890
Likes: 0
Received 14 Likes
on
6 Posts
First thought is the accelerator pump. You say you played with that a bit, but what does the squirt going into the primaries look like from the AP nozzles when you operate the shaft by hand?
I'm having a small blip or hesitation at the bottom of each gear change. It kinda sounds like the engine is coughing... If you can picture that. Ot's not enough to stall the engine. It does'nt always happen, but when it does happen it is noticeable. It doesn't matter if you are over or under 2000 RPM. It seems to NOT do it when the choke is pulled out halfway.
Suggestions?
I've played with the timing and it doesn't matter where I set it at. I've played with the idle mixture, doesn't affect it. I've adjusted the TPS looking thing on the front of the carb and no change. I have also played with the accelerator pump a bit and didn't notice a change.
What else could it be? The car drives great other than the little blip here and there. Cruises smooth. Has plenty of power.
My old Nikki (79 model) did this too except it would buck when cruising at 55 MPH. Is it just how I have something hooked up that could be wrong?
Could I need a new dizzy rotor?
-79 engine with an 83 Nikki.
-Emissions removed.
-Vacuum secondaries.
-br8eq stock plugs.
-Pacesetter header to a stock exhaust.
-Holley blue fuel pump set at 4.5 PSI (Racing Beat recommended pressure).
-Racing Beat carb hat.
-Idles at 800 RPM.
-Vacuum advance is plugged into the 2nd to the left nipple on the carb spacer.
-Crank case and float bowl vents?? are plugged into the 2 nipples nearest the mixture screw. (Is this correct??) As stated in the emissions removal by Carl. Everything else is capped with an ACV block off plate with gasket.
Suggestions?
I've played with the timing and it doesn't matter where I set it at. I've played with the idle mixture, doesn't affect it. I've adjusted the TPS looking thing on the front of the carb and no change. I have also played with the accelerator pump a bit and didn't notice a change.
What else could it be? The car drives great other than the little blip here and there. Cruises smooth. Has plenty of power.
My old Nikki (79 model) did this too except it would buck when cruising at 55 MPH. Is it just how I have something hooked up that could be wrong?
Could I need a new dizzy rotor?
-79 engine with an 83 Nikki.
-Emissions removed.
-Vacuum secondaries.
-br8eq stock plugs.
-Pacesetter header to a stock exhaust.
-Holley blue fuel pump set at 4.5 PSI (Racing Beat recommended pressure).
-Racing Beat carb hat.
-Idles at 800 RPM.
-Vacuum advance is plugged into the 2nd to the left nipple on the carb spacer.
-Crank case and float bowl vents?? are plugged into the 2 nipples nearest the mixture screw. (Is this correct??) As stated in the emissions removal by Carl. Everything else is capped with an ACV block off plate with gasket.
03-01-09, 11:28 AM
#3
The 2 squirts looks pretty steady. Is my emissions removal and vacuum routing setup correctly?
I noticed 2 vacuum nipples on top of the carb on the exhaust side under the hat. It was like this when I got the carb. I just capped them. What are they for? Cruise control, AC, or something?
On another note. (Could be related) ...
I'm having hot start problems with this carb. It didn't do this with the 79 carb. The car starts great when it's cold, puffs out a little smoke for 20 seconds or so with the choke pulled. After you've been driving for awhile and you go into a store for 10 or more minutes it takes it a bit to start. You have to push the throttle all the way down and start it. Takes 10-15 seconds sometimes, but it has never NOT started.
I have read about the float bowl vent and I need to know if I have it hooked up correctly and if that could be the problem.
I guess I should post pictures of my setup and connections.
I noticed 2 vacuum nipples on top of the carb on the exhaust side under the hat. It was like this when I got the carb. I just capped them. What are they for? Cruise control, AC, or something?
On another note. (Could be related) ...
I'm having hot start problems with this carb. It didn't do this with the 79 carb. The car starts great when it's cold, puffs out a little smoke for 20 seconds or so with the choke pulled. After you've been driving for awhile and you go into a store for 10 or more minutes it takes it a bit to start. You have to push the throttle all the way down and start it. Takes 10-15 seconds sometimes, but it has never NOT started.
I have read about the float bowl vent and I need to know if I have it hooked up correctly and if that could be the problem.
I guess I should post pictures of my setup and connections.
03-01-09, 12:01 PM
#4
Nikki-Modder Rex-Rodder
Join Date: Feb 2001
Location: Trying to convince some clown not to put a Holley 600 on his 12a.
Posts: 2,890
Likes: 0
Received 14 Likes
on
6 Posts
The two nipples on the exhaust side of the air horn were for the altitude idle compensation valve. They do need to be capped.
The hot start issue is indicative of a venting problem that causes slight flooding. Next time you anticipate this happening, don't try to start it. Instead, pop the gas cap & see if it "whooshes".
I think you'll know for sure if you actually get it to start without depressing the pedal.
The hot start issue is indicative of a venting problem that causes slight flooding. Next time you anticipate this happening, don't try to start it. Instead, pop the gas cap & see if it "whooshes".
I think you'll know for sure if you actually get it to start without depressing the pedal.
03-01-09, 12:26 PM
#5
I know that the crank vent is less than optimal... I plan on putting a barb on the hole on the RB hat and running a hose from the purge valve and crankcase nipple. I plan on putting actual vac caps on those nipples with screws... Ran out of caps.
I just want to make sure the rest of this is connected right...
From the left...
1st hose is the vac advance.
2nd hose is the small bottom vac line from the purge valve.
3rd hose is the top vac line from the purge valve.
Bottom hose of the purge valve is dangling loose (venting to atmosphere?)
Gas tank breather line is dangling loose.
The screw in piece in the center of the carb... what us that? It had a vacuum cap on it when I got it. Should it be uncapped?
I have also read mixed opinions on whether the small nipple on the shutter valve should be capped. I capped it, but many say leave it uncapped. Could this cause a small bottom end blip? Maybe too much airflow at once and the valve is supposed to control it?
I just want to make sure the rest of this is connected right...
From the left...
1st hose is the vac advance.
2nd hose is the small bottom vac line from the purge valve.
3rd hose is the top vac line from the purge valve.
Bottom hose of the purge valve is dangling loose (venting to atmosphere?)
Gas tank breather line is dangling loose.
The screw in piece in the center of the carb... what us that? It had a vacuum cap on it when I got it. Should it be uncapped?
I have also read mixed opinions on whether the small nipple on the shutter valve should be capped. I capped it, but many say leave it uncapped. Could this cause a small bottom end blip? Maybe too much airflow at once and the valve is supposed to control it?
03-17-09, 09:48 PM
#6
Well I figured it out... Both the cause of my hesitation and hot start problem...
To recap... The car was having a blip on the bottom end of every gear. After 5 minutes or more of sitting after being driven it would always flood and be hard to start back up (although it always did restart). After cooling all the way down it would always start great, but smoke for a couple minutes.
First of all today I went out for a spirited drive. I came back popped the hood to have a gander at the fluid levels etc a few minutes after I got home. I smelled gasoline as usual coming from the engine area so after not seeing any line leaks I immediately removed the carb hat and I see 1/2 an inch of gasoline inside the carb and more was dribbling out of the jets. I just thought the constant fuel smell was a carburetor thing.
I got some cleaner and wiped off the dirty float bowl glass on the back and front so I could actually see it for once. After sitting for 5 minutes the float glass was empty. I restarted it and I noticed that the float glass reading was way too high. Racing Beat recommended that I run 4.5 PSI on my Nikki... Ok, well something isn't right about that because the bowl level was to the top of the glass with the car running. I lowered it down to 2 PSI and it evened out to the middle of the glass.
When I first spotted the gasoline I noticed that it was dribbling out of the jets and settling on top of the throttle plates. On this go around I noticed that none was leaking out at all. So in conclusion the fuel level being too high and the fuel pressure being too high seemed to have been causing it to seep out of the bowl and flood the engine.
I rerouted some vacuum lines on the carb spacer and eliminated the purge valve. I looped the two bowl vent barbs together and swapped the vacuum advance line over the the 2nd from the left. I also put real vacuum caps where I used screws...
There must be something to running lower pressure on a Nikki...
The car idles better, starts better, has better bottom end as well as top end, and no more annoying hesitation!
To recap... The car was having a blip on the bottom end of every gear. After 5 minutes or more of sitting after being driven it would always flood and be hard to start back up (although it always did restart). After cooling all the way down it would always start great, but smoke for a couple minutes.
First of all today I went out for a spirited drive. I came back popped the hood to have a gander at the fluid levels etc a few minutes after I got home. I smelled gasoline as usual coming from the engine area so after not seeing any line leaks I immediately removed the carb hat and I see 1/2 an inch of gasoline inside the carb and more was dribbling out of the jets. I just thought the constant fuel smell was a carburetor thing.
I got some cleaner and wiped off the dirty float bowl glass on the back and front so I could actually see it for once. After sitting for 5 minutes the float glass was empty. I restarted it and I noticed that the float glass reading was way too high. Racing Beat recommended that I run 4.5 PSI on my Nikki... Ok, well something isn't right about that because the bowl level was to the top of the glass with the car running. I lowered it down to 2 PSI and it evened out to the middle of the glass.
When I first spotted the gasoline I noticed that it was dribbling out of the jets and settling on top of the throttle plates. On this go around I noticed that none was leaking out at all. So in conclusion the fuel level being too high and the fuel pressure being too high seemed to have been causing it to seep out of the bowl and flood the engine.
I rerouted some vacuum lines on the carb spacer and eliminated the purge valve. I looped the two bowl vent barbs together and swapped the vacuum advance line over the the 2nd from the left. I also put real vacuum caps where I used screws...
There must be something to running lower pressure on a Nikki...
The car idles better, starts better, has better bottom end as well as top end, and no more annoying hesitation!
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03-18-09, 08:06 AM
#10
Lives on the Forum
That's funny. Today was the first time that I took a good look at your little list on your first post. I was just scrolling downt to reply, and ask why you were trying to run 4.5 on a Nikki. Sorry I didn't catch that sooner, or I could have save you a bit of trouble... 
03-18-09, 09:17 PM
#12
I need to install my Exedy clutch first! The stocker slips like a bitch. I noticed that I had the bowl vent nipple caped too for some dumb reason I can't remember... (DOH!) That helped out a lot too... I just ran a vac line from it under the car to dribble. BTW I installed my new OEM replacement fuel pump and ditched the regulator. Runs a lot better and simpler.
The Holley pump is up for sale!
Anyone know why RB recommends 4,5 PSI on a Nikki?
The Holley pump is up for sale!
Anyone know why RB recommends 4,5 PSI on a Nikki?
03-19-09, 08:45 AM
#13
Waffles - hmmm good
iTrader: (1)
So they can sell fuel pumps 
Also if you hear a hiss whenever you open your gas cap, then your venting from the tank is either not working or you have it plugged up at the engine bay somewhere. Ask me how I know.
Also if you hear a hiss whenever you open your gas cap, then your venting from the tank is either not working or you have it plugged up at the engine bay somewhere. Ask me how I know.
03-19-09, 07:49 PM
#15
It would always overflow the bowl and end up boiling inside the TB. I finally noticed it was doing that a while back when I popped the hood 5 minutes after a drive. Sounded like a coffee pot peculating.
The Holley kit is only a $1300 fix though... It's way more affordable than a Nikki!
The Holley kit is only a $1300 fix though... It's way more affordable than a Nikki!
07-15-09, 02:28 PM
#17
Lives on the Forum
It would always overflow the bowl and end up boiling inside the TB. I finally noticed it was doing that a while back when I popped the hood 5 minutes after a drive. Sounded like a coffee pot peculating.
The Holley kit is only a $1300 fix though... It's way more affordable than a Nikki!
The Holley kit is only a $1300 fix though... It's way more affordable than a Nikki!
07-15-09, 04:35 PM
#18
I need to install my Exedy clutch first! The stocker slips like a bitch. I noticed that I had the bowl vent nipple caped too for some dumb reason I can't remember... (DOH!) That helped out a lot too... I just ran a vac line from it under the car to dribble. BTW I installed my new OEM replacement fuel pump and ditched the regulator. Runs a lot better and simpler.
The Holley pump is up for sale!
Anyone know why RB recommends 4,5 PSI on a Nikki?
The Holley pump is up for sale!
Anyone know why RB recommends 4,5 PSI on a Nikki?
This thread has been resurrected from the dead?
Turns out my bogging issue was caused by the old points. Cleared up when I went with 2dgfis.
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