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| Cause of goo on the intake https://slantsix.org/forum/viewtopic.php?t=30250 |
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| Author: | Reed [ Mon Jul 28, 2008 7:25 am ] |
| Post subject: | Cause of goo on the intake |
I am working on my brother's van again and I have a question. The van has been converted toa Super Six using a Carter BBD. The front of the carb obviously has a leak somewhere because it is covered with crud but the rest of the carb is clean (since I rebuilt the carb before installing it). Also, the intake manifold and throttle linkage is covered with a sticky black goo that appears to be dribbling out of a port on the bottom of the float bowl directly above and between the mixture screws. It looks lke this port leaks and the leak has blown back over the throttle linkage. When I last gave the van to my brother I got 18 MPG highway with it and did not notice any fuel leaks. My brother reports that the van gets about 10 MPG and now I see an obvious fuel leak from somewhere on the carb. The van pulls 19-20 inches of vacuum at idle, so I don't think the throttle shaft bushings are bad. However, this carb was supposed to be used with a charcoal cannister and the van no longer has one. My question is what are the possible causes ad cures for this leak? I suspect that this is the cause of the poor gas mileage my brother is getting. Italso looks like this s more than just a float bowl gasket leaking. Is the fuel coming from the port on the bottom of the float bowl? Should I cap this port on a carb meant to be used with a charcoal cannister where the vehicle does not have a charcoal cannister? Thanks for the input! |
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| Author: | Aggressive Ted [ Mon Jul 28, 2008 9:32 am ] |
| Post subject: | |
I would cap it, sounds like it is boiling over from heat soak or a high float level. I would do Dan's heat soak mod or mine with the 3/8" phenolic spacers and some sort of heat deflector. Is it a 1920? or 1945 Holley? |
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| Author: | Reed [ Mon Jul 28, 2008 10:04 am ] |
| Post subject: | |
Nope, it is a BBD. I am thinkning I will try reconnecting it to the charcoal cannister since the port that appears to be leaking is the cannister purge port. I found the charcoal cannister tucked down by the frame rail underneath the passenger seat. I need to check if it is still functional though. At least a new filter... |
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| Author: | Joshie225 [ Mon Jul 28, 2008 10:09 am ] |
| Post subject: | |
It really sounds like the float got heavy and it causing a little flooding. You'd have to be leaking an awful amount of fuel to lose that much economy. I say you're in the market for a good carb kit and float. |
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| Author: | Reed [ Mon Jul 28, 2008 10:34 am ] |
| Post subject: | |
Thanks. I will tear the carb down and give it a look-see. I can't remember if this carb has a brass or nitrophyl float. It does appear to be a rather large leak. I will post pictures later. |
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| Author: | Aggressive Ted [ Mon Jul 28, 2008 12:11 pm ] |
| Post subject: | |
Hopefully it isn't oil blowing out of the dipstick! and just fuel spillage mixed with dirt and grim. |
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| Author: | SlantSixDan [ Mon Jul 28, 2008 12:40 pm ] |
| Post subject: | |
All BBDs (and BBSs) have brass floats. This kind of overflow problem can be caused by a too-high float setting, a leaky inlet needle and seat, excessive fuel pressure, and/or pressure buildup related to heat soak. Occasionally the brass float can develop a leak and take on fuel internally, but it's not at all common. Definitely do the fuel line mod, and check the float level. On a vehicle equipped with evaporative emission control (via charcoal cannister '72+, crankcase '71 and '70 California) there should be no ports open to the air. See the Carter BBD operation and repair manual (pdf) |
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| Author: | Reed [ Mon Jul 28, 2008 4:13 pm ] |
| Post subject: | |
Thanks Dan! I already ordered in a new float, and I will buy some hose when I pick it up at the parts store. I already re-routed the fuel line over the valve cover (mid 80s slant vans come that way from the factory). I need to guard against heat soak and buildup becaue vans are notorious for temperature buildup in the doghouse. |
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| Author: | Joshie225 [ Mon Jul 28, 2008 4:38 pm ] |
| Post subject: | |
On the heat soak issue... I'm thinking junk yard electric fan, relay and a bathroom fan timer. Dial in 5-minutes or so when you park and walk away. |
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| Author: | Aggressive Ted [ Mon Jul 28, 2008 8:59 pm ] |
| Post subject: | |
Joshie, That's pretty close......give or take 30 seconds....  After doing the electric fan mod, and the heat shield mod, and the fuel line mod, when I go shopping I leave the system armed so if it starts to heat soak the fan kicks on and cools everything down. Bye the time I come back on hot 90 degree plus days it starts right up! Sweet 
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