New vacuum gauge

Discuss mechanical problems here.

Moderator: Moderators

alanworland
Minor Legend
Posts: 1257
Joined: Tue Jan 30, 2007 10:09 pm
MMOC Member: No

New vacuum gauge

Postby alanworland » Fri May 10, 2019 11:28 am

Sometime ago I made inlet manifolds for my sidevalve and these accommodate a pair of the original carburetors. This seems to work well enough giving unfathomable horsepower!
However I connected the manifold stubs together with a small ID pipe with a 'T' take off for a vacuum gauge which results in a pulsing gauge needle - it wrecked the gauge.
I picked up another gauge at an autojumble to replace the busted one but I am planning on fitting some sort of damper/chamber in the pipework before the gauge in an effort to smooth out the pulses, has anyone gone this route or is there a better way?
High accuracy is not required, I just don't want to wreck another gauge!

Image

Alan
Image

Declan_Burns
Minor Legend
Posts: 1733
Joined: Wed Apr 18, 2007 7:32 am
MMOC Member: No

Re: New vacuum gauge

Postby Declan_Burns » Fri May 10, 2019 2:31 pm

Alan,
When I did the testing with the PCV valve on the MG, I had the same issue with the needle wanting do go into orbit. Just stick a cigarette filter in the tubing as a damper and the problem is solved and the needle us steady. You can find them everywhere for free - even on the side of the road :D
Regards
Declan


Regards
Declan

Monty-4
Minor Fan
Posts: 394
Joined: Sun Oct 26, 2014 7:17 pm
MMOC Member: Yes

Re: New vacuum gauge

Postby Monty-4 » Fri May 10, 2019 8:34 pm

Interesting, I have a vacuum gauge that is connected to a manifold/carb spacer on one side of a twin carb setup - no pulsing whatsoever. Perhaps it is more exposed to the turbulence when plugged directly to the manifold?
68' 4-door Saloon, another 'Monty'.

alanworland
Minor Legend
Posts: 1257
Joined: Tue Jan 30, 2007 10:09 pm
MMOC Member: No

Re: New vacuum gauge

Postby alanworland » Fri May 10, 2019 10:06 pm

Thanks for your replies, don't really understand why it should pulse and did consider just connecting it up to just one pair of cylinders but as both intake stubs are tapped it seemed a good idea to tap off of both?
I shall get hold of the nearest cigarette filter and give it a try! Not really bothered if it makes the gauge sluggish as long as it stops it getting broke.

Alan
Image

RobThomas
Minor Legend
Posts: 2520
Joined: Thu May 11, 2006 10:34 am
MMOC Member: Yes

Re: New vacuum gauge

Postby RobThomas » Sat May 11, 2019 6:28 am

Jet out of the carb of an old Fiat etc. Tiny little drilling in it removes the pulsing. I just shove it down the vac hose after filing it down to fit.
Cardiff, UK


Who is online

Users browsing this forum: No registered users and 11 guests