No vacuum! To drill or not to drill?

[JKY]

On checking over my plenum whilst it is off of the car, I have found that the vacuum take off has actually never been drilled through the casting and the car has never actually had vacuum advance from new!!!.
Now I know that a couple of others have found this, and infact many may be running no vacuum without realising it, but what is the concensus - should I drill this out or just leave it as is and continue to run without vacuum advance??
Was this deliberate by land rover when they made these plenums or was it a manufacturing error?

[spend]

Sounds like it may not be the original plenum, some older flappers had the vacuum take off in the trumpet base IIRC.

[Johno]

Drill it . . .attach it, see if it improves it ?

If it doesn't, then bung it and be back where you started.

So many of these are bunged and ignored anyway, what the cost, a small hole where it's supposed to be ?

[TVR Beaver]

Did you see the post the other day on this... now on page 3 ... I'll try link it but not sure if this will work?...

http://www.pistonheads.com/gassing/topic.asp?h=0&a... advance question

[spend]

If you have the pipe connector, it is likely you have a hole but it's just got gummed up - the hole is not as big as the pipe or stub id IIRC.

[JKY]

The plenum is the original and has the take off, and the vacuum pipe was always connected to it, just that the take off does nothing as it does not go all of thew way through.
Agreed, i can just drill it and plug the pipe again if no improvement. Just strange that a few seem to have been fitted like this!

[JKY]

I thought that initially but plenum is spotlessly clean and I have carefully checked, there is no hole right through.

Edited by JKY on Tuesday 16th March 17:49

[JKY]

Ok, I have drilled a very small hole through. Comes out just fractionally ahead of the butterfly, afm side, when closed
Many thanks

[GunShot (Wound)]

JKY said:

The plenum is the original and has the take off, and the vacuum pipe was always connected to it, just that the take off does nothing as it does not go all of thew way through.
Agreed, i can just drill it and plug the pipe again if no improvement. Just strange that a few seem to have been fitted like this!

Mines the same.
Even put a new vacuum advance unit on last year but made no difference.
Removed tubing and bunged up both ends.

[GunShot (Wound)]

JKY said:

The plenum is the original and has the take off, and the vacuum pipe was always connected to it, just that the take off does nothing as it does not go all of thew way through.
Agreed, i can just drill it and plug the pipe again if no improvement. Just strange that a few seem to have been fitted like this!

Mines the same.
Even put a new vacuum advance unit on last year but made no difference.
Removed tubing and bunged up both ends.