Carb icing symptoms???

[2002Targa]

Hey all,

I've seen a lot of posts on icing, but it’s pretty much just reasons to keep the water tube on the manifold.  I’ve been having a weird cutout lately in the mornings similar to running out of gas or water in the tank (checked both) 

Particulars: 74’, pertronix, stock fuel pump with a switchable electric pump inline, new fuel filters, 32/36 with a water bypassed Cannon manifold, 35º-40º outside temp.

I have about a 45min commute fm Wasilla to Anchorage, usually around 25-30min into the drive it starts bucking/cutting out.  If I pull over for 10-15 min the car works normally and no problems in the afternoon.

I’ve seen lots of info for icing for airplanes, but couldn’t find anything 02 specific.  Sooo, does this sound like icing?  

 

Thanks,

TK

PS, I've also swapped the pertronix with points, problem still there.

[jireland2002]

When it begins cutting out check the coil.  The coil should be warm but if it is too hot to leave your hand on it that is a bad coil.  Probably not but it will eliminate one variable.

[TobyB]

When it does it, are you in a particularly damp part of your commute?

I used to get it on the bridge across Lake Washington, when the bridge 

dropped down onto the lake itself.

 

The only real way to check is to pop the cover off the air cleaner- you'll see the white

furball in the venturi.  Sometimes the outside of the carb ices up, too, but that's

not always the case.  If you gas the hell out of it, will it run wide- open?  On a 

32-36, the secondary probably wouldn't ice....

 

Icing's quite possible.  As is a plugged fuel tank vent- in hotter temps, the fuel 

will vaporize to fill the space in the tank more readily.  That one you rule out

by listening for airflow when you pull the gas cap.

 

What do you have for an air cleaner?  The stock setup with the 

flapper box preheats the air off the exhaust manifold for a reason...

 

hth

t

 

 

Edited May 1, 2019 by TobyB

[2002Targa]

Didn't think about the coil, will check in the AM.  It keeps chugging along, but just sputters at 60-70 like it's going down to two cylinders.  Best I can tell, ignition wiring is good.  K&N air filter and the tank is just vented straight out underneath the trunk.

[TobyB]

Next time it does it, pull over, pop the aircleaner top off, and see if there's an iceberg in there!

 

in for pix,

t

[tzei]

Sure i could happen. Bypassing intake warming (water and air) doesn't help. There are also some fuel additives that supposedly helps to reduce icing. Might wanna give those a try? Do you have any preheating system like Defa or alike? Also blocking some of the radiator area helps in winter. Hotter thermostat is one thing too.

[Lorin]

My old car would ice the carb pretty consistently in light rain/drizzle, 30's to 40's temp at highway speeds. On a road trip once, i didn't want to stop so i fashioned cardboard shield for the entire front of the carb attached with zip ties and that solved the problem. I kept that cardboard in the trunk and used it a few more times over the years.

 

 

I bet it would solve your issue or at least ID your problem.

 

[Hans]

The wind chill is going to get the carb below freezing at speed. Back in the day, part of the winterization ritual was to move the snorkel lever to the winter setting. Since you don't have that , perhaps the shield would help a bit. A good dose of methyl hydrate gas line anti freeze might help, but the problem is very cold air blasting by and thru the carb.

['76mintgrün'02]

The intake tube under the carburetor is dark rust-brown, but white with frost in this photo.

 

 

[2002Targa]

6 hours ago, TobyB said:

Next time it does it, pull over, pop the aircleaner top off, and see if there's an iceberg in there!

 

Sho-nuff, as soon as it started cutting out this morning, I pulled over and popped the air cleaner off.  Nice little frost icicle going from the venturi all the way down to the throttle plate.  Held it wide open with my hand for a minute and the engine heat melted it all away.  Good to go!!!

I tried to get a pic, but couldn't get my phone out before it mostly melted.

[TobyB]

I'm going to beat Tom to this punch-

 

get thee a stock air intake, and hook up the preheat

to the exhaust manifold!

 

Bet that fixes ya!

 

Airplanes have this problem on a regular basis.

 

t

 

[2002Targa]

That would do it,  but I'd have to mickey mouse something, I have a stahl header on it.  . 

Or I could just get off my lazy ass and install the megasquirt that I've had sitting in the garage for the last 2 years...

[Mike G]

I vote mega squirt but reeve’s will have everything you need for a super simple carb heat set up. 

[2002Targa]

Ooooh I like that!