Progressive carb freezing up?

[johnny27030]

I just got my car together last night and I drove home when it was about 40 degrees out. And on my way home the car started losing power and backfiring occasionally. I got home and checked the valve train (still warm) and it looked good. By the time I got done checking clearances it had cooled a bit and I started the car and it run fine no more skipping and backfiring. Could this be the carb freezing up? I have no heat risers to the carb. Any help would be greatly appreciated.

[Matt Wilson]

even when a carb is not totally frozen up, it can have some icy buildup on it and on the manifold. If it is humid where you live, I would assume carb icing would be more of an issue. I would put in those heat risers, as the manifold heat actually helps keep the fuel atomized and helps keep it from going back into reversion.

Was it lean backfire? or is there too much gas?
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1972 Standard Beetle
1969 Baja Beetle

[Randy in Maine]

It is a problem with all centermounted carbs and why VW went with heat risers.

Thought about dual carbs?

[johnny27030]

Im not sure if it was a lean or rich backfire it was dark and I didnt pull any plugs. I will check this afternoon. Can anyone tell me where to get the riser tubes at?
Thanks
Johnny

[Matt Wilson]

I see the whole manifol with tubes on cip1, for like 85 bucks, but I'll bet if you call redline weber they might have the parts you need.

www.redlineweber.com
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1972 Standard Beetle
1969 Baja Beetle

[johnny27030]

OK I pulled the plugs yesterday. One plug was fouled and they all were black from running to rich. So I changed plugs and wires and went for a ride. The car ran like crap for a couple of miles so I turned around and went home. On the way back the car ran like a top. I havent took another plug reading yet b/c I was about frooze in the 25 degree weather with the wind blowing. The car also has a bit of a flat spot around 3000rpm. Is that from the idle jets or the mains or is it where they are in transistion between each other that is causing that. Any way I am going to tinker with the car a bit tomorrow and see what happens. I have a set of main jets a little smaller I may put in it to see how it does after I take another plug reading. I dont know if the carb was running rich where the carb may have frooze up? or if that is just the jets im running. Any input from you guys is greatly appreciated with any logical suggestions.

[propflux01]

sounds to me like a combination choke and icing problem. Those proggys really need the manifold heat to work right, especially with an 'open' air cleaner..which brings me to question #2, did it rain in days previous? iahve seen air filters get watersoaked and richen the mix.

[johnny27030]

I adjusted the carb float up a bit changed back over to points to see if the pertronix may have been skipping and installed a new coil. Went for a ride of about 10 miles. The car ran ok but sometimes had a little hesitation. So I decided to take a plug reading. Cylinders 1 3 & 4 looked good, maybe a little rich but pretty good. No. 2 was black and ashy. Im wondering if I am having an ignition problem or a fuel problem or could it be the valves not seating off properly. The motor is freshly rebuilt with aproximatly 50 miles on it. Im going to change the cap and button just b/c it is the only thing not been changed since the rebuild. So I will post later as to how that works out. Any advice would be appreciated.

PS There has been no rain here in a while it has actually been pretty dry.

[Gary Massin-Ball]

You need a wrm air intake box. You can mcgiver one out of a "danish cookie can". and some OE vew bits. Just attatch the lid of the cookie can upside down under the air filter bottom bracket then reassemble the air filter back on. Then take the base of the can and add a 2" nozzel ( i use the connector pipes from the stock beetle muffler) and just pop rivet it to the cookie can base. Then place the bottom part of the can onto the inverted lid attached to the carb add the 2" fresh air hose down to a hot air intake elbow through the tin to the cylinder head and the progressive will run perfectly in cold wheather. In the summer just remove the bottom end of the can.

[Loopole]

your problem is icing. the hot air box is a good idea, but also how is your heat riser working? i believe aircooled net seels the trick intake for the progressive, the heat goes all the way up to the carb base. also, are you running an aftermarket exhaust? if you are, the heat riser will not function worth a crap, the stock system picks up the exhaust from number 2, right at the exhaust port, routs through the manifold, then down to the muffler, the result is a high pressure at the exhaust port, and al low pressure at the muffler, the result is much great flow through the heat riser and is why the stock system works so well, even the complete functioning stock system is inadequate in certain conditions, such as 35 degress and raining hard and light throttle, mine would ice up every time in certain conditions, and behave just as you explained, the solution? dual carbs. you will never go back.

[LD]

Just pour in a bottle of gas anti-freeze like Heet or STP gas treatment. Used it for years.
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'62 2276 Sedan

www.bkcruizers.com

[jamestwo]

Hey LD
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hEY, lOOK, i'M WRONG HALF THE TIME, AND THE OTHER HALF i'M NOT SURE WHAT THE HECK i'M TALKING ABOUT. MY POST ARE FOR MY OWN ENTERTAINMENT VALUE ONLY.