Wrapping up a full tear down on my 1275 and cant remember what these two hoses do. I have tried searching but couldn't fund exactly what i needed.
1&2 in the picture. Thanks in advance.

 

On my HIF6 #1 is not connected to anything and #2 is the distributor vacuum advance.

Jeff

 

So is your plugged or vented to air via a small filter?

 

My book on SU's, on a diagram for HIF models calls your #1 "vent tube", like Jeff on my 6 I have this just open. I tried plugging it originally but there was a noticable problem when I did that. A filter wouldn't hurt but mine's been open for 7 years with no ill effects. As noted #2 is the vac' advance to the dizzy.

 

Regarding my the vent tube. It is not connected to anything ... not plugged ... not filtered. At least on my 1275 block w/ HIF6 carb.

Jeff

 

1 is fuel overflow pipe this just attaches to a 1/4"dia metal tube that goes down the clutch casing and past the subframe, 2 is vacun advance tube that goes to dizzy............

 

I ran a hose to the front right side so if there is an overflow it doesn't come anywhwere near the manifold or engine. It's more of a fire precation. Like MK1Leg said , usually there's a tube draining it off just in front of the clutch case. near the subframe.
The only time it will overflow is if your float sticks in the open position and doesn't stop the fuel from overfilling the float bowl or the float itself is set to low.

 

Ok - I now have first hand experience with this vent tube.

During last weekend's track event I started smelling fuel while driving. Once I got out of the car I opened the bonnet and the entire RHS of the bonnet area was covered in sprayed fuel. Luckily for me there was no drama, just a problem that I had to fix.

So it turns out that if, like in my case, the brass tang that's attached to the carb float breaks away from the float that vent line will dump raw fuel directly out of the carb into the engine area just above the exhaust manifold.

Words of advice - if you have one of these carbs do yourself a favor and run some 1/4" fuel line from that vent line (1 in above picture) to somewhere under the engine so that it'll dump the fuel away from the hot exhaust.

 

ahhhhhh

a vent - yes - an OVERFLOW vent

yes MK1 you said that, but not in the words that clicked with me . . .

I think I'll make a note in my book

and run a hose this weekend