Author Topic: Vacuum tap via manifold?  (Read 527 times)

Offline thebluepotato

Vacuum tap via manifold?
« on: January 28, 2019, 08:34:55 AM »
All - been looking for correct thread/pitch brass bung that will allow a small vac line tap...will be a reducer in nature, but not finding right thread pitch that reduces down to say a 1/8" barb.  Will look something like this.

Anyone have a suggestion?


Offline MPlayle

Re: Vacuum tap via manifold?
« Reply #1 on: January 28, 2019, 10:49:57 AM »
For that size, are you looking for where to connect a distributor vacuum advance line?

The manifold port is usually used for a brake booster when attached.

Most of the dual carb sets I have seen have the distributor vacuum advance going to just one of the carbs at the nipple just above the butterfly valve of the carb.


Offline drmini

Re: Vacuum tap via manifold?
« Reply #2 on: January 28, 2019, 03:38:16 PM »
Do they have a Royal Brass & Hose company in your town?  They're a national chain of hydrolic hose suppliers.  They seem to have all kinds of fittings and hoses for just about any application you can think of.  Check out your phone book or Google them. 


Offline jeff10049

Re: Vacuum tap via manifold?
« Reply #4 on: January 28, 2019, 11:39:01 PM »
amazon has it too. https://www.amazon.com/MettleAir-Male-Tubing-Fitting-Connector/dp/B00S8CUJTY


(edit) Just thought of something if that's some odd thread I don't think it is...but if so drill a hole in that plug you have and solder in a short length of copper oil line for an oil pressure gauge and you'll have what you want to connect a hose to.
« Last Edit: January 28, 2019, 11:43:52 PM by jeff10049 »

Offline thebluepotato

Re: Vacuum tap via manifold?
« Reply #5 on: January 29, 2019, 07:57:08 AM »
Thanks chaps for the replys...just to clarify, this tap is simply for vac gauge only and wanted something easy to tap into.  This seemed to be the right spot from all he older articles I have seen.  But open to suggestions.

Looking at some of the links posted above now.  Many thanks.

Offline Jimini II

Re: Vacuum tap via manifold?
« Reply #6 on: January 29, 2019, 11:18:52 AM »
That thread pitch is hard to find this side of the pond. I have heard that the cv joint has the same thread so you can maybe go from that or the nut that is used.
If it were mine i would consider drilling and tapping the current blank/plug you have and installing the nipple you need or you could drill and tap the other boss on your twin set up as that is where i have seen a number of them done, of course this will require removing the intake which the previous thought would not.
« Last Edit: January 29, 2019, 11:21:08 AM by Jimini II »

Offline jeff10049

Re: Vacuum tap via manifold?
« Reply #7 on: February 09, 2019, 11:05:29 PM »
if it's 1/8" pipe it should not be that hard to get you might end up with 1/8" BSP a straight rather than tapered version but it will still work ok just put some teflon tape on it. What part of a CV joint has that? Not saying some don't just not seen any NPT or BSP threads that size on a CV is it for a grease fitting?

Offline Jimini II

Re: Vacuum tap via manifold?
« Reply #8 on: February 12, 2019, 01:53:57 PM »
Don't know what part of the cv was used as i only heard about it but i imagine the outer stub that the castle nut tightens down on to.
Maybe it was not even the right thread just a "get me home fix".

EDIT: To be clear i was referencing the brake servo take off hole but from looking at the picture the plug he is using is not that big.
« Last Edit: February 14, 2019, 06:09:46 PM by Jimini II »