When the temp is around the freezing mark and there is rain/drizzle/fog or even wet snow, the base of my carb ices up and she starts chugging and missing and black smoke pours out of the exhaust. The only thing to do when this happens is to pull off the highway and turn the engine off. The heat from the engine compartment rises and thaws out the carb. This takes about 5 minutes. But this gets dangerous at times when it happens during rush hour traffic.

I'm pretty sure this happens because of the EGR valve being removed and also i recall a small tube that also rotted off from under the carb base that went to the EGR valve. When the tube rotted off it sounded like a major exhaust leak. I plugged the leak with a pipe plug from the hardware store.

I'm guessing that this rotten tube carried exhaust gasses under the carb base providing heat.

Question is this: How do i provide some other means of heat to keep the ice from forming. I took the flexible heat riser pipe (that runs to the air cleaner snorkle) and routed it to the carb's base....this doesn't seem to send enough heat though.

give me some ideas....i can't wait for summer to get here and it looks like a long wet winter ahead!

 

I forgot to say this is happening on my 81 F150 4.9L 1BBL carb.

 

You may have to hook up the original plumbing if the heat pipe isnt keeping the ice away . Whenever the air temp & dewpoint are close to one another icing will occur . What you might try as a cheaper solution is install a higher temp thermostat to keep the engine temps up .

 

By the design of the I-6 manifolds the intake is mounted directly above the exhaust and there is a passage between them. This keeps heat in the carb base and in the manifold. Is the old egr base still intact below the carb? I live in VT where the weather NEVER gets decent and I run my truck with an I-6 in all sub zero weather w/o the problem. Do you have a preheater hose connected from the shield to the intake? That also helps heat the carb.

 

Hello Bob_vt

As Paul mentioned in his post, it is the dew point factor thats iceing me up. I can drive all day long in sub zero temps because the air is so DRY the carb doesn't ice up. But warm the temperature up to around 30 to 40 degrees, add ALOT of moisture and here comes the ice problems on the carb. Seems that if i could keep damp air from hitting the carb i wouldn't get any iceing.

Moist wind-chilled, air slapping a cold metal, fuel filled carb and the result is Frosty the Carberator. Heard of Bud Ice....i have Carb Ice!

The EGR valve is gone. There is a metal plate in its place. I have routed the pre-heat tube from the exhaust manifold shield to the base of the carb. I replaced the thin-wall aluminum aftermarket preheat tubing with a thicker fiberglass one this past weekend.

I'm also thinking of going to Home Depot to buy some water pipe insulation. Maybe by wrapping some of this on the new preheat tube and possibly placeing some around the carb base i might just get lucky and put an end to the iceing problem. I'll keep you posted on how it goes. Thanks for the ideas.