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Sat Nov 07, 2009 4:42 pm

After 15 minutes of run time my intake manifold starts to ice up, is this normal for a Bug ?

Sat Nov 07, 2009 4:49 pm

I just posted about a clogged heat riser. Sounds like that might be your problem. Mine was JAM PACKED!! Might want to take a look and see.

Sat Nov 07, 2009 5:01 pm

No it is not normal. plugged heat riser, no warm air into the carb if it still has all of the stock piping.

Sun Nov 08, 2009 4:06 am

The intake manifold heat riser is clear, I just put this motor back in and the riser was packed solid with carbon but I cleaned it out real good. Running a new Bocar 34 pict carb , oil bath air cleaner with heat tubing and 009 dizzy, seems to run good however it has not yet been out of the driveway so with a nice coat of frost on the intake after 15 minutes in the drive I have to wonder what it will do with higher rpm's at road speed.

Sun Nov 08, 2009 6:31 am

By chance is it a Baja?

Sun Nov 08, 2009 7:14 am

No Baja just all stock 73 SB 1600 DP.

Sun Nov 08, 2009 7:30 am

Do those heat risers get hot to touch with your gloved hand after a 10 minute ride?

They should. Lots of times the after market exhausts are not properly drilled out to allow the heated exhaust into the risers.

Sun Nov 08, 2009 9:33 am

Randy in Maine wrote: Do those heat risers get hot to touch with your gloved hand after a 10 minute ride?

They should. Lots of times the after market exhausts are not properly drilled out to allow the heated exhaust into the risers.

The left "feed" side the heat riser on my 1600DP gets hot pretty quickly but the right "receiver" side just gets lukewarm. I checked the heat riser with an old clutch cable and found no clogs. I even replaced the muffler with a good German aftermarket (it's correctly drilled out) and nothings changed.

I don't have any icing but I'm sure the car will run better, especially when cold if both sides were hot. Anyone else have this problem?

Sun Nov 08, 2009 8:35 pm

Randy in Maine wrote: Do those heat risers get hot to touch with your gloved hand after a 10 minute ride?

They should. Lots of times the after market exhausts are not properly drilled out to allow the heated exhaust into the risers.

They get warm but the ice is center manfold by the vacuum port, todays temperatures were warmer than yesterdays and it did not ice up , insurance and reggie later this week so I;ll drive it and see what happens......

Mon Nov 09, 2009 4:31 am

Just doin it in the drive? It will be running rich w/choke on. Rich condition will run colder. Get it out & drive the hell out of it, let us know then.............JP

Mon Nov 09, 2009 6:34 am

Heat risers work great with a stock muffler. Exhaust is 'sucked' from one side to the other. After market 'pipes' not so much. Some gasket kits come with heat riser gaskets that have a 'regular' hole and a small hole. This was to help with the 'flow' of hot exhaust thru the riser. You can have a clear unclogged riser pipe but if you can't get a flow thru it it won't work right.

Mon Nov 09, 2009 6:39 am

runamoc wrote: Heat risers work great with a stock muffler. Exhaust is 'sucked' from one side to the other. After market 'pipes' not so much. Some gasket kits come with heat riser gaskets that have a 'regular' hole and a small hole. This was to help with the 'flow' of hot exhaust thru the riser. You can have a clear unclogged riser pipe but if you can't get a flow thru it it won't work right.

My muffler is stock and I tried the large and small hole gasket on the receiver side of the heat riser. Is that the correct side for the small holed gasket?

Tue Nov 10, 2009 5:26 am

You might also check your peashooters. As I recall the peashooters are supposed to be a certain depth in the muffler in order to create vacuum so to make the hot gasses flow across from one side to the other. I don't remember the details but there is a certain dimension required.

Fred

Tue Nov 10, 2009 7:22 am

fmartin_gila wrote: You might also check your peashooters. As I recall the peashooters are supposed to be a certain depth in the muffler in order to create vacuum so to make the hot gasses flow across from one side to the other. I don't remember the details but there is a certain dimension required.

Fred

I have adjusted them according to the book but I'm not sure if it matters with my particular muffler. I've read that the original design has a heat riser exit pipe in the vicinity of one peashooter. My two mufflers just dump the exit gasses in the main body of the muffler, there is no extention into the peashooter. I'm not sure if this was ommitted for cost reasons or that the design is different.

Tue Nov 17, 2009 1:03 pm

I am having problems with the carb on my '69 Baja sweating since it turned cold. It has a aftermarket exhaust on it and I do not know if the heat riser tubes are open or not. I will check the next time I drive it and see if they are getting hot.

Tue Nov 17, 2009 9:39 pm

I had one do that one time turned out to be the seat valve in the carb vibrated loose.

Thu Nov 19, 2009 4:52 pm

I checked my '69 Baja after I was at work today and the intake was iced up. I am going to check the heat tubes this weekend.

Sat Nov 21, 2009 5:14 pm

I checked my heat riser today and it is not clogged. Is there supposed to be opening for the exhaust to go through the tube from the exhaust tubes? I have a after market exhaust on my Baja and no holes go into the exhaust tubes.

Sun Nov 22, 2009 5:00 am

On rt side u have a hose going down to the flat engine tin,is the '90 degree bend elbow' installed and hose attached,it curves around to the cylinder and warm air goes to air filter. Most of these get removed in a repair etc.

Sun Nov 22, 2009 6:24 am

When I bought the Baja it had a small after market air filter on it. I will look and see if the 90* degree elbow is still on it. If not, what can I do to get some warm air to the air filter?