carburetor problems
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carburetor problems
How do i tune my carburetors rebuilt them but the car runs but it doesnt idle and it hesitates 1.6 r16
- spl310
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Re: carburetor problems
Where are you located?
"Wow, a Roadster!" Stuart Little
1967.5 2000
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1967.5 2000
1967.5 2000
1964 1500
1964 1500
1967.5 1600
1968 chassis
2006 Acura MDX
2013 Volkswagen Jetta TDI wagon
1995 F350 Powerstroke!
More...
- notoptoy
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Re: carburetor problems
Best write-up here: http://www.datsunroadsterranch.com/
"When all else fails, force prevails!" Ummm, we're gonna need a bigger hammer here.
67.5 SPL311 H20 w/5 speed
65 Impala Convertible
2017 C43 AMG
67.5 SPL311 H20 w/5 speed
65 Impala Convertible
2017 C43 AMG
- Gregs672000
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Re: carburetor problems
Yes, do look through the carb tuning info, great stuff there by people who really know them. We are happy to help with any questions as you progress, and may be able to route some folks to you if desired, once we know where the car is located... Welcome!
Greg Burrows
'67 2000 #588
Tacoma, WA
'67 2000 #588
Tacoma, WA
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Re: carburetor problems
My front carb is pulling way too much air and the back carb is pulling almost none. Tried adjustments to no avail. What am I over looking. Mark
- keith0alan
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Re: carburetor problems
Looks like the datsunroadsterranch.com site is down. I need to fix that. The info is also on 311s.org. Air flow balance is off. Check the valve lash and then look at my carb tuning info on 311s.org.
- nismou20
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Re: carburetor problems
Pulling the pistons and domes off allows you to see roughly where the butterfly valves are in relation to fully closed throttle. This may help you get in the ballpark if you are totally off. Then use the balance screws to fine tune. Also helps to get the nozzles close.
2004 Chevy Tracker
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- RustBucket
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Re: carburetor problems
Couple questions:
1.Did you use a uni-syn or equivalent to measure flow? Adjust dog bones for open throttle, screws for idle. I think that dogbane adjustment is more important. I spend more time off-idle.
2.Check the oil in the carb pistons. I used 20wt motorcycle shock oil. This may help with acceleration hesitation. Check site for other oils that can be used (Marvel Mystery, etc...)
3.You could check the floats are still floating and that the valve is adjusted correctly too.
You can also check a multitude of other things, but start there.
The RoadsterRanch write up is awesome and really helped me. Its duplicated somewhere here on 311's.
I had to rebuild my carbs twice to get it right. Quick and dirty the first time and precision and clean the second time.
Good luck!
Rustbucket
1.Did you use a uni-syn or equivalent to measure flow? Adjust dog bones for open throttle, screws for idle. I think that dogbane adjustment is more important. I spend more time off-idle.
2.Check the oil in the carb pistons. I used 20wt motorcycle shock oil. This may help with acceleration hesitation. Check site for other oils that can be used (Marvel Mystery, etc...)
3.You could check the floats are still floating and that the valve is adjusted correctly too.
You can also check a multitude of other things, but start there.
The RoadsterRanch write up is awesome and really helped me. Its duplicated somewhere here on 311's.
I had to rebuild my carbs twice to get it right. Quick and dirty the first time and precision and clean the second time.
Good luck!
Rustbucket
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
67.5 1600
Orange County, CA
67.5 1600
Orange County, CA
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Re: carburetor problems
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67 SRL311-00279-resto project
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- bossbob
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Re: carburetor problems
I haven't worked on my carbs in a while, but I noticed the center section of the Unisyn is adjustable, how much of a gap should there be to allow enough air through the Unysin so the carb doesn't choke out?
Just curious for the next time I tune the carbs.
Just curious for the next time I tune the carbs.
68 Roadster 1600
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63.5 Galaxy Conv. 427 Dual Carb, 4 spd
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70 Boss 302
65 K-Code Fastback
69 Mach 1 393 Stroker 5 spd
63.5 Galaxy Conv. 427 Dual Carb, 4 spd
72 Ranchero
65 GT Coupe
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- bossbob
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Re: carburetor problems
This is what I was pointing at, found it on another site.
The Unisyn has a "dial" adjustment in its throat. It is a little adjustable
disc dial. Turn the disc dial one way and it lets more air in. Turn it the
other way and it lets less air in. You'll see the air gap increase and
decrease ( a little) in the throat of the Unisyn as you adjust this disc
dial. With carbs so badly out of sync, as yours undoubtly are, you will have
to start with a dissimilar adjustment of this "dial" for each carb. Adjust
the Unisyn for each carb so that the engine stays running, sllllooooowly
adjust the idle speed bringing them into a state where both carbs allow the
engine to run with the Unisyn in place. Unless the mixture adjustment is
really out of adjustment bad or unless you have a mechanical issue, this
should be fairly easy to accomplish. If the mixture is that badly out
causing a no idle condition on one of the carbs, this will have to be
corrected first. Usually I'll turn the mixture in till it misses and the
idle roughens, and then out until it smoothes out enough to stay running.
The Unisyn has a "dial" adjustment in its throat. It is a little adjustable
disc dial. Turn the disc dial one way and it lets more air in. Turn it the
other way and it lets less air in. You'll see the air gap increase and
decrease ( a little) in the throat of the Unisyn as you adjust this disc
dial. With carbs so badly out of sync, as yours undoubtly are, you will have
to start with a dissimilar adjustment of this "dial" for each carb. Adjust
the Unisyn for each carb so that the engine stays running, sllllooooowly
adjust the idle speed bringing them into a state where both carbs allow the
engine to run with the Unisyn in place. Unless the mixture adjustment is
really out of adjustment bad or unless you have a mechanical issue, this
should be fairly easy to accomplish. If the mixture is that badly out
causing a no idle condition on one of the carbs, this will have to be
corrected first. Usually I'll turn the mixture in till it misses and the
idle roughens, and then out until it smoothes out enough to stay running.
68 Roadster 1600
70 Boss 302
65 K-Code Fastback
69 Mach 1 393 Stroker 5 spd
63.5 Galaxy Conv. 427 Dual Carb, 4 spd
72 Ranchero
65 GT Coupe
70 Boss 302
65 K-Code Fastback
69 Mach 1 393 Stroker 5 spd
63.5 Galaxy Conv. 427 Dual Carb, 4 spd
72 Ranchero
65 GT Coupe
- GeoffM
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Re: carburetor problems
Don't know where you got that info but you want the unisyn to have as little effect on the air flow as possible while still being able to read vacuum. hence the ball in the middle of the clear tube is a good rule of thumb.
Geoff
1969 SPL-311
1969 SPL-311
- Gregs672000
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Re: carburetor problems
The advantage of the "snail" version of the carb balancing tool is that you can hold the snail over the throat without changing flow much, allowing you to read it carefully, take your time and make minor adjustments. My car is very sensitive to different flow, and the Dellortos allow for balancing all 4 throats individually of needed, so the snail has been a must have tool.
Greg Burrows
'67 2000 #588
Tacoma, WA
'67 2000 #588
Tacoma, WA
- spl310
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Re: carburetor problems
Do y'all realize that the OP posted once 4 months ago - his first post - and never responded to anything else?
"Wow, a Roadster!" Stuart Little
1967.5 2000
1967.5 2000
1964 1500
1964 1500
1967.5 1600
1968 chassis
2006 Acura MDX
2013 Volkswagen Jetta TDI wagon
1995 F350 Powerstroke!
More...
1967.5 2000
1967.5 2000
1964 1500
1964 1500
1967.5 1600
1968 chassis
2006 Acura MDX
2013 Volkswagen Jetta TDI wagon
1995 F350 Powerstroke!
More...