Vac timing

Hi all,

Searched but couldnt find what I was after.

Someone has had a fiddle with my breating system and hoses (last owner),
what Im wanting to know is the one way valve on the pipe to the dizzy for advanced timing, what way arround should it be if there at all.

I ask this as when I have the pipe completley off the car and try sucking and blowing it only allows one way air travel and I think its the wrong way as it wont allow any vac past the valve to the dizzy, thus not allowing the advanced timing.

Thanks all

Since the vacuum is created in the manifold/plenum I'd expect the valve to allow air to travel from the vacuum unit to the plenum, thereby creating the vacuum.

First thing I'd test though is whether there is any vacuum, with the engine running just stick your finger over the end of the pipe.

It is also possible that the vacuum unit is faulty or stuck. You can test this by sucking on a length of pipe and seeing if the base plate in the dizzy moves.

Thanks Wookie, thats the thing tho, is with this 'one way valve' inline is its not allowing a vac at the dizzy end but it is at the inline valve inlet, so I knoe this thing is stopping the vac.

Its a black disk like thing with one end of it brown, and the brown end is closest to the dizzy.

If I suck the pipe from the other end it allows flow tho.

:nopics: need pics to be sure !!

Brown end is closest to distributor on mine also.

I think you'll find it a vacuum damper. Which means it will be free flowing one way but limiting the other way.

There is far too much vacuum at the plenum so the damper reduces it. The reason you can't suck through it one way is simply because you can't suck hard enough!

If you suck on the advance unit you can move it just by mouth. A big engine sucks harder than you can, so the damper reduces the level down to a suitable level.

Sorted?

Thankyou Mr Noisy, so if i was to get a vac pump on it I should be able to pull though the damper?

Is the damper there on all of the vac advanced units? As I read alot of people able to just suck down the pipe and move the timing?

This one?

Hi mate

I don't know what sort of vacuum the RV8 makes in its plenum of tickover but in theory of you replicate this then it should suck through it yes.

Mine is definitely impossible to suck through one way, but afaik my advance works just fine!

I assume the unit is there on all RV8s yes, but I don't know for sure. I know that you should be able to move the advance by mouth, but it's not clear as to whether this should be through the damper or direct into the advance unit...

Sorry I can't be of more help!

Cheers

Thanks again mate, just going though everything at the mo as it feels low for the 'power' it should have and then vibrates and runs of of steam as I get higher up the rpm past 3500k.

I know its only there for part throttle crusing to advanced the timing but just going though everything I can.

Thanks once again.