Vacuum Readings
Turbo Mini Forums

Hi all,

last week i was playing with the car and noticed that my vacuum readings on my boost/vacuum gauge at idle dropped right off and site just below 0 (0 being Atmosphere) where previously the readings were around 15 to 20 inches or merc.

i checked the readings on the megajolt unit and it had the same readings i checked over the lines and blocked some off and still the same.

i have them connected to the little nipple at the front of the carb just in front of the done/bell.

when i drive the car and back of throttle at above 2000rpm the vacuum readings go donw to 20 or so but then straighjt back to just below 0, same thing if i bring the revs up to around 1500 the vacuum readings go to 10 to 15 as soon as i take foot off the reading goes to just beow 0 again.

any ideas? should i take the readings off the manifold instead off that nipple? but then again this is where i have always used.

thanks

Grant

Edited by RED850 on 24th Jun, 2007.

179hp on 12psi 1293cc of pure A series
14.0et @101 mph

you will have a leak ....some where ?

inlet gasket ?
maniflod area ?
carb maybe?

find it!

yeah i thought i might but cant seem to see it, does that port have vacuum all the time? it doesnt close off at idel does it?.
can someone check theirs and tell me?

thanks

179hp on 12psi 1293cc of pure A series
14.0et @101 mph

maybe your on a ported vacuum take off ,and its not giving vac at tickover , try another place eg the manifold servo point ?

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Hi,
You've got it connected to the vacuum advance port on the carb.
This shuts off at idle.
Tee it into the vac connection for your MJ
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

the megajolt uses the same port, so i guess i will change them all.
where should i take blow off valve from too? i guess all from the manifold...but there is so much from there then, boost gauge,blow off valve, MJLJ and booster.

Grant

179hp on 12psi 1293cc of pure A series
14.0et @101 mph

Hi,.
Yes, best bet is to take everything off the manifold.
My idea is to drill a hole or 2 in the manifold and fit a couple of pieces of copper/nickle brake pipe in, with the end slightly flared to help hold the pipe on.
Put a windscreen washer tee piece on each one, gives you 4 outlets
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

Don't share vac signals... a vac guage will effect the signal getting to the MJ etc etc.

Alex

AlexF

Hi,
You'll need more holes then!
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary

cool, well i might put a T in the booster line for the blow off valve and gauge and then drill and tap a small nipple for the MJLJ vac reading as its the most important.

so does anyone use the vac port off the carb for anything?

thanks guys

179hp on 12psi 1293cc of pure A series
14.0et @101 mph

Hi,
It's useless for anything other than the clockwork dizzy :(
Cheers,
Gavin :)

VEMs Authorised Installer / Re-seller. K head kits now available!

WB/EGT gauges. Click here for customers write-up

Visit www.doyouneedabrain.co.uk

My Mini build diary