Carb / manifold icing...again

[sdoyle23]

hi,
1967 beetle, 1500. Had a problem with icing, pulled the manifold, cleaned it out. It does grt hot now, manifold neck freezing. Will only stay at idle if revving or zip tie on the step cam.
New (rebuilt german):
Distributor
Solex 30 pict 1
Fuel pump
Also installed new stock exhaust.
It has the original 67 oil bath.
Here's a pic of the engine.

Am i overlooking something?

[KTPhil]

Do you have a thermostat/flaps installed so it warms quicker?
Do the weighted flaps in the air cleaner work the way they should, pulling warmed air at idle? Do the small paper hoses connect to properly-aimed nipped drawing heated air?

[sdoyle23]

Not sure what you mean by thermostat / flaps. The flaps on the oil bath move freely, never had one of these before, but everything seems to be present. I have the small hoses running down and laying on the tin below the heads, the original tin (small pipes for those hoses) are not present.

[sdoyle23]

How i have the small hoses running.

[sdoyle23]

Just checked, no thermostat present.

[cb1990s]

The thermostat (at ‘engine cold’) keeps the flaps on the shroud closed until the engine warms up and the thermostat opens up.

The result is more cooling air when the engine is warm, but when the engine is warming up and the flaps are closed the engine is able to get to temp quicker due to lower cooling air flow. I can’t see why this would lead to carb icing; that is more likely caused by blocked pre-heat pipes on the inlet manifold (these coke up over time).

[sdoyle23]

Thanka cb, that originally what i thought the issue was. Pulled and cleaned out the manifold.

[sgmalt46]

sounds like a tuning issue. even with the pre-heat working on the manifold the manifold will still sweat under the carb. even with a blocked manifold no thermostat no air cleaner pre-heat it is hard to get icing idle problems like described. not in the middle of June anyway.
_________________
55 deluxe 23 window bus
64 crew cab
55 rag top beetle
66 beetle
71 square back (sold) ! good luck with it Henry!
46 beetle 552nd royal army service corps CCG

[sdoyle23]

Checked the points, set properly. Static timed it. Valves were done recently. Screwed in the carb all the way, backed out 1 1/2 turns. Not sure what else i should be doing. Recently changed plugs and wires as well.

[KTPhil]

Looks like you are missing some tins and hose nipples for the pair of smaller cardboard hoses. With them, air is drawn from an area near the exhaust valve in the head, and not just from cooling air exiting under the car. With them, you should have hotter intake air and maybe less icing trouble.

With a thermostat & flaps in the fan housing, the engine warms up faster. Those two 1" hoses will still draw hot air form the heads even with the thermostat closed. Faster engine warmups may help avoid icing during the warmup period.

[sdoyle23]

carb is not sweating, it's frozen. It's 24 degrees on the neck, used an ir thermometer.

[sdoyle23]

I'm not disagreeing with ANY of the advice given here, and i intend on sourcing those parts...BUT
It seems these fixes generally only help on a cold engine, after runnig for 10 minutes or so, shouldn't it be warm enough from the intake alone? Having those tins would warm it faster, but still should get sufficiently warm over time?

[brando90gl]

When you installed the new muffler and peashooters, how did you install the tail pipes? Are they shoved all the way in as far as they’ll go or are they set up to allow the flow to the heat risers? There is a specific depth for them to be installed. I experienced this first hand recently, I bought a set of new pea shooters and put ‘em all the way in, this caused my heat riser to go warm, not hot anymore. I pulled the peashooters out about a quarter of an inch or so, and my heat risers are hot again.
_________________
67 Type 1
68 Campmobile
70 Single Cab

[sdoyle23]

The heat risers are hot, 150-200 degrees on the hot side. I did put new pipes on, put them in 1.8 inches per Bentley. They are not pushed all the way in. While we're talking about mufflers, I'm not getting "thr bug noise" which is a bummer.

[brando90gl]

I’d have to agree with sgmalt46 then, sounds like a tuning issue. I have a 67 with a 1600dp in it, still have the 67 oil bath, but I do not have the preheat hooked up and I do not get icing at all. Just slight condensation depending on humidity levels.

You are a step ahead and actually have the preheat mostly correct, so I’d lean towards a carb issue.
_________________
67 Type 1
68 Campmobile
70 Single Cab

[sdoyle23]

I want to blame the carb. I just don't know what the solution is. When the butterfly is completely open, it dies. It's a 30 pict 1, there aren't alot of adjustments to make so it's frustrating.

[sgmalt46]

without being there hard to say. all I know is I have rarely seen icing trouble even with all the pre-heat stuff missing and manifold plugged soild.
no preheat to the air cleaner ect.. I never checked intake temp with a thermometer . so can't comment on that .but it always "feels" cold?
still think it is a carb adjustment issue. adjust the carb when the motor is warm. 1 1/2 turns out is a starting point. probably too lean back it out some more.
mess with the mixture to get the best idle. once warm go in till it stumbles then back off 1/2 to 1 turn. all the pre-heat advice is good but is over thinking the problem. and check the idle jet maybe plugged? engine looks nice by the way

Steve
_________________
55 deluxe 23 window bus
64 crew cab
55 rag top beetle
66 beetle
71 square back (sold) ! good luck with it Henry!
46 beetle 552nd royal army service corps CCG

[sdoyle23]

Just ran it again for about 10 minutes. Again, have to zip tie the step cam and lever to keep it running, preheats hot, manifold neck freezing. What should i be looking for with the carb?

[sdoyle23]

Thanks, steve. This is where it was a couple of weeks ago.

[sgmalt46]