What are the symptoms of carb icing? I have a Yaw carb on a stock 12A,no choke. It was around 10 degrees here this morning, the car was running ok once I got it started. It gets a little stubborn in the cold without a choke. Anyway, it was running fine until about halfway warmed up, then it started acting like it was "loading" up, it cleared out after revving it a little on the highway.
Any thoughts? It is also driving me crazy with a inconsistent idle, I have it set at 1k rpm which is about 100 rpm higher than I want to be, and sometimes it idles stable at 1k, and then sometimes it drops down to 150 to 300 rpm and usually stalls. This problem is not new though, it also happened with my stock carb. Ignition?
Thanks,
dave

 

my stock carb does the same thing, if i'm understanding you right.

starts up fine, idles a little low w/ the choke engaged for me until it warms up to about half way, at which point it likes to sputter and eventually die. it sorts itself out when the car has been fully warm for about ten minutes.


i just live with it.

 

it's been around 10F too here. But I drive my Mikuni driven 12a with out any icing occuring. Does your Yaw Nikki Carb setup have coolant going into the intake manifold? I know it tends to get icy if it is plugged to keep coolant out and if its humid out. Even on a mild day(40-60F). If you don't run the stock air cleaner that has the hose that goes to the heat shield on the exhuast, you will have little you can do to combat that. Thats why its there.

If you did not know a carb kinda works like air-conditioning evaperator, except outside air pressure is the compressed state of the system, and below the throttle plates, at crusing speed or idle, the vaccum creates a state at which water vaper in the air will freeze at a higher then 32F. The cure to this is either get some warm air going in or play with the throttle a lot and that will keep it from icying. The more varing the throttle the better.

 

Yes the manifold is plugged, no coolant running through it anymore. That is a good analogy about the a/c. I was aware that the carb worked that way, and I was also aware that I may have an icing problem. I am not absolutely sure that is the problem though. I was hoping maybe somebody who had experienced an icing problem might share some thoughts.
Thanks,
Dave

 

Dave,
My Yaw does the same thing, and I don't even have my coolant passages plugged. I have my idle set to 500, and was going to reset it to 1000 for the winter, but I just let it warm up in the driveway. I like to baby her, so for me it's just insurance that she does'nt go anywhere till she's "God-damned good 'n ready!".
But even after the temp is up, I sometimes stall out when stopping. It takes a bit longer to get the whole engine compartment warm enough.

I saw Steves reply on the other site, and I'm real curious...Think I'll have a peak to see if there is acctually ice in the venturis.

 

Yea,
I thought the same thing. I want to take a look down the barrels and see if there is really ice build up. I don't have a cold air intake though, it is just pulling engine compartment air. I am thinking about putting the deceleration (sp?) dashpot back on to see if it will help with the stalling. It's wierd, sometimes it will stall, sometimes it settles right down to idle at 900-1000 rpm. I just bought a 85 distributor and ignitors, I am going to get rid of my 80 setup. Maybe that will help. I also plan on doing an MSD upgrade, but not for a while. I have sunk too many dollars into my little black beauty for now.
Oh by the way, I would opt for sex now, then go for a ride in the RX.
just my opinion.
hanman