Fitting a vacuum gauge

[daverclasper]

Hi. Thinking of fitting one to Vitesse (I know its probably is an unnecessary "must have"). I only want to do this if it's relatively straightforward and simplistic ?.

Car has the standard PCV arrangement and would like to use a period Smiths gauge . Would it be possible and work out, to put a T piece in the middle of the S shape hose that's between the valve and inlet manifold.

If so, what other bits would I need, eg, type/size of hose, hose size reducers, etc

Ta

[Iain T]

Honestly fit a Lambda sensor and air/fuel ratio meter before a vacuum gauge. 

I bought a stand alone vacuum gauge with fittings and plugged it in from the rocker cover to manifold and bypassed the pcv. Used to see what the vacuum was but didn't really aid me to tune the engine anywhere near as much as an afr meter. It aids ignition setting but if you have pancake filters it can muck up the reading. 

Iain 

[Colin Lindsay]

51 minutes ago, Iain T said:

Honestly fit a Lambda sensor and air/fuel ratio meter before a vacuum gauge. 

I bought a stand alone vacuum gauge with fittings and plugged it in from the rocker cover to manifold and bypassed the pcv. Used to see what the vacuum was but didn't really aid me to tune the engine anywhere near as much as an afr meter. It aids ignition setting but if you have pancake filters it can muck up the reading. 

Iain 

I think it's more likely one of the Redex Robot gauges or the small multi-coloured vacuum gauges, the trick is to drive with the needle always in the green.

It just needs a manifold takeoff, but I think putting one into the S-hose at the PCV wouldn't give an accurate reading as you're getting the reading from the rocker cap end, not the intake manifold via the carbs. I'm always open to reeducation but I think you'll have to drill and tap the manifold.

 

[Iain T]

16 minutes ago, Colin Lindsay said:

just needs a manifold takeoff, but I think putting one into the S-hose at the PCV wouldn't give an accurate reading as you're getting the reading from the rocker cap end, not the intake manifold via the carbs. I'm always open to reeducation but I think you'll have to drill and tap the manifold.

I might have misremembered and only fitted to the manifold? 

Anyway drive like you've stolen it, it's more fun! 

😁

[daverclasper]

Thanks Guys. I did wonder about its accuracy, as even though the S hose is downstream from the valve and does go to manifold, will not maybe as accurate as direct from the manifold?

[dougbgt6]

I have a vacuum gauge off a "T" piece to my servo. It exactly mirrors the "by ear" method of setting the timing. Turn the dizzy for the highest revs, OR highest vacuum, it's the same thing. Then turn back a gnats OR ! bar, . And you got it. I love the vacuum gauge whizzing about, impresses the ladies. 

Doug

[Pete Lewis]

i would drill and tap the manifold (use a well greased drill to collect swarf)  

you will need a restrictor in the supply pipe  many add a short bit of brake pipe and squash it with pliers till you get a steady reading or the needle will flutter a lot 

then driving with the highest vacuum is no fun at all 

Pete

[dougbgt6]

Dave has a Vitesse, I think, do they not have a tapped hole in the manifold already? Dunno, I only know about very late MK3 GT6s! 

My vacuum gauge came with a restrictor fitted. 

Doug

[Peter Truman]

54 minutes ago, Pete Lewis said:

 

you will need a restrictor in the supply pipe  many add a short bit of brake pipe and squash 

Pete

In my youth when writing telex's from the phone from dads UK Co' to his Aus Co. esp on a Sat morning (UK 11hrs behind) they used to be called snubbers, we had a box of them in our home workshop here for process control equipment think they were brass 1/4 in barrell unions with a very small hole/orifice in a disc in them, Also used in PC equipment on my own water supply pressure monitoring equipment. Nothing as crude as a crimped pipe but kiss always works!