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Fine tuning new carb
https://slantsix.org/forum/viewtopic.php?t=12103		 Page 1 of 1
Author:  NewLancerMan [ Sun Mar 06, 2005 3:45 pm ]
Post subject:  Fine tuning new carb
Hey everyone,

Ok I just put a carb on that I have rebuilt, and it seems to run pretty well. I started its initial adjustment by screwing the mixture all the way closed, then opened it two full turns. I let it warm up, unscrewed until it was at its fastest, then went until it slowed down and got rough again. I chose the spot in between and left it there. Throttle response seems good, all is ok.

BUT, when its at idle in neutral, there's a little sputtering, like its missing every once and a while. You can hear it in the exhaust as well. I was going to have a go at it tomorrow to figure out what the problem might be. Too rich/lean? Timing? Just wanted to get some advice from folks here first.

Thanks!
Author:  Dennis Weaver [ Sun Mar 06, 2005 4:09 pm ]
Post subject: 
...adjust the mixture screw until it just gets the most RPM (or highest vacuum if you're using a gauge like your supposed to) then leave it there. Adjust idle speed to spec using the curb idle (throttle stop) screw. Then check the mixture once again, going for max RPM/vac. Adjust curb idle again if necessary.

D/W
Author:  Rust collector [ Sun Mar 06, 2005 4:59 pm ]
Post subject: 
Just make adjustments to all the other things, before you do the carb, Then listen to someone else for the rest.
I welded in a o2 sensor, and I guess that gives you some idea how the mixture is, but don´t look too much at it.
Author:  NewLancerMan [ Sun Mar 06, 2005 5:04 pm ]
Post subject: 
Ah Dennis, you forgot my birthday last week--I asked for the vacuum gauge! :D Its on my ever-lengthening list to buy.....any recommendations? One with all de attachments?

MJ
Author:  Rust collector [ Sun Mar 06, 2005 5:14 pm ]
Post subject: 
Oooops! I forgot too.
Do you want an inflatable one?
Author:  NewLancerMan [ Sun Mar 06, 2005 5:18 pm ]
Post subject: 
Nah just one that tests suction! I'm good to go in the other dept ;-)

MJ
Author:  NewLancerMan [ Fri Mar 11, 2005 7:11 pm ]
Post subject:  Update: Warmup idling then no-runny!
So I was warming the car up, checking the idle speed at the various settings on the idle cam, and was getting ready to disconnect the vacuum line and adjust the carb, when blam, car died. Tried to start it several times, I get nothing. Things I noticed while warming up:

1--small amount of smoke coming out of the valve cover through the oil breather cap

2--slight knocking noise from the engine

3--carb appears to be leaking a little gas from the accelerator pump or possible around the gasket (tightened the screws just to be sure but they felt good).

here's what the carb looks like:

Image

thanks in advance

MJ
Author:  Doctor Dodge [ Sat Mar 12, 2005 8:53 am ]
Post subject: 
Check for spark, check for gas and check to see if the distributor rotor is still turning 'round and round'. (check that little plastic distributor gear)
DD
Author:  NewLancerMan [ Sat Mar 12, 2005 10:59 am ]
Post subject: 
yeah had spark, thought I had gas. Well lo and behold, it was completely empty. Strange since I haven't driven it all that far since I got it, but I have done a lot of idling and tuning. Guess its time to elevate fixing the gas gauge on the todo list ;-)

Thanks for the help--I feel dumb!

BUT, I have another problem with the carb!

When I screw the idle mixture screw all the way in, the car still runs. I've sprayed around for air getting in, but I didn't get any increase in idle speed when doing so. Any particular hot spots on BBS carbs to check for?

Other things to look at?

Thanks!

MJ
Author:  Reed [ Sat Mar 12, 2005 11:21 am ]
Post subject: 
If the car still runs with the mixture screw turned all the way in I would suspect that you have a bad gasket or a cracked carb body that is allowing gas to still enter the intake manifold. Time for a good and thorough rebuild of the carb.
Author:  NewLancerMan [ Sat Mar 12, 2005 11:47 am ]
Post subject: 
ok i'll keep looking and but a rebuild kit.

thanks!

MJ
Author:  SlantSixDan [ Sat Mar 12, 2005 12:20 pm ]
Post subject: 
Quote:
yeah had spark, thought I had gas. Well lo and behold, it was completely empty.
Under certain circumstances, that'll sometimes cause the car to stall.
Image
Quote:
When I screw the idle mixture screw all the way in, the car still runs. I've sprayed around for air getting in, but I didn't get any increase in idle speed when doing so. Any particular hot spots on BBS carbs to check for?
If the throttle plate is open wider than factory spec, closing the idle circuit won't necessarily stall the engine. Remember, factory spec on these early applications was WAY low (550rpm in Neutral with the high beams on!). Usually 550rpm is not a realistic idle speed. 650 starts getting more realistic.

Next thing to try is pulling the PCV valve off the valve cover and plugging it with your thumb, with the mixture screw all the way seated. Engine stalls? OK, time to look at what's coming through that PCV pipe (excessive blowby? Engines can and will idle on oil fumes).
Author:  NewLancerMan [ Sat Mar 12, 2005 12:41 pm ]
Post subject: 
Quote:
Next thing to try is pulling the PCV valve off the valve cover and plugging it with your thumb, with the mixture screw all the way seated. Engine stalls? OK, time to look at what's coming through that PCV pipe (excessive blowby? Engines can and will idle on oil fumes).
Just to make sure I'm not confusing terminology and chasing windmills. On *this* valve cover (vs. my 225) I have a blowby tube. It just dumps to the ground and the large port on the carb that I assume would be fed by a PCV valve has a cap over it. I tried spraying this cap and nothing went through.

I'm going to adjust the idle to 650 in Park with headlights on WARM and see what happens ;-)

I'll be back!

MJ
Author:  SlantSixDan [ Sat Mar 12, 2005 12:52 pm ]
Post subject: 
Quote:
Just to make sure I'm not confusing terminology and chasing windmills. On *this* valve cover (vs. my 225) I have a blowby tube. It just dumps to the ground
Oh yeah, sorry, only California and New York cars got PCV in '61 and '62. 48-state and Canada cars didn't get it as standard equipment til '63. So, disregard that bit.
Author:  Eric W [ Sat Mar 12, 2005 11:21 pm ]
Post subject: 
Quote:


Image


Classic. :mrgreen:
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