Fuel Tank Vent Pipe

[Trident team]

I have just had some fuel supply issues with my mates car [June 1965 build date].
The problem started when, after the car was starting and running normally with no sign of any issues, I attempted to start it after a few days to take it for a test drive and it wouldn't start.
All the normal checks were carried out.
Plugs, points, coil, plug leads, various wiring for security and correct connection etc.
Then a fuel line to the front carbie was disconnected and it was dry.
So then the pump was checked for delivery and there was no ''spurting'' of fuel as you would expect especially when it was a new pump recently fitted and she had a full tank.
I then jacked up the rear of the car and was preparing to disconnect the fuel line from tank to pump, to check for a blockage, I thought I'll give it one more try and the pump then started ''spurting'' as I cranked it over.
All very strange I thought.
Then my wife wandered in and said are these tanks vented?
Why didn't I think of that?
Upon removal of the vent pipe it was ''blown'' out with compressed air and a fairly large amount of dirt was
collected in a plastic bag, but I also noticed that a small brass restrictor was located inside the pipe [see images] Are these normal as the Parts Catalogue doesn't show it?
Engine is now starting and running normally.

 

[David Baldock]

I'm sure it shouldn't be there but I can't imaging why it is or how it came to be there! Maybe somebody used a piece of pipe from something else to make it up and it just happened to have it in it?

Dave B

 

[Keith Halstead]

Never seen one.

 

[Trident team]

Thanks Dave and Keith
Restrictor is destined for the bin
Cheers Geoff

 

[Brian c]

Geoff
Very impressed with your wife's mechanical knowledge.

 

[Trident team]

Me too, sometimes it amazes me.
She is especially handy when I have been rebuilding steering boxes, juggling all those pesky ball bearings and shims...I never seem to have enough hands or fingers.

 

[Trident team]

For those interested in this thread, the local auto electrician near me, of many years experience made an
observation that might make some sense regarding the ''restrictor'' in the fuel tank vent pipe.
He said that the restrictor may have been fitted during its racing days to prevent or more likely, slow the
loss of fuel if the car became inverted following a racing incident/accident.
I guess the thinking behind that would be the same as the advent of foam filled fuel tanks.
Your thoughts please...
Geoff

 

[David Baldock]

Sound's plausible to me Geoff. Maybe the restrictor helped the gunge to build up.

I wonder what the minimum diameter requirment for the vent pipe might be? Maybe the small hole was suffisient.

Dave B

 

[Trident team]

Yes Dave the small hole would enough to allow venting.
But it would be a problem when dirt accumulated or a wasp was looking to build a new home.
The Australian Cortina GT 500 had twin filler caps located behind the rear windscreen and used
a pair of filler caps from a motorcycle and on the inside is a brass ring in which is a small hole.
This is the only vent [x 2] and they work perfectly.
The design of fuel storage on the GT 500 is that they have the standard tank in the boot floor
which is gravity fed from an auxiliary tank fitted behind the back seat and the original filler pipe
and vent line are deleted with the hole in the original tank for the filler pipe blanked off.
Geoff