Advance/retard ?

[tractor]

_{plenum now been claimed by snapper paul}

[Guest coops222]

No worries, got one I made myself... thamks for the generous offer. I dont think that was my problem anyway.

[Guest coops222]

hi guys,

i decided to empty my tank by pumping petrol out via the fuel pump and i noticed air bubbles being pumped through the inline fuel filter.... surely this is not normal... or is it?

[sj-bradley]

It could be caused by cavitation from the pump mechanism itself. It's probably just fuel vapour you can see and should pose no problems so long as they are relatively small.

 

(Cavitation - bubbles formed when high speed objects move through a liquid. Something that submariners need to avoid ... )

 

Simon.

[Longboarder]

No it's not normal. It means that the suck at the pump is being resisted by a partial blockage and drawing air into the system between pick-up and pump. There should be virtually no resistance to the pump sucking! Is there a filter pre pump that could be blocked? Is there crud blocking the pick-up? Are the pre pump pipes all open?

 

Nigel

[Snapperpaul]

A thought on disconnection of vac to dizzy

The whole points plate is rotated by vacuum if disconnected perhaps plate is moving, you may need to pin it

I sort of remember talk of this problem when racing

[Snapperpaul]

And another thought

If you pin the plate you may fix the advance to 1 point so best to look further into my ramblings

[Guest coops222]

hi guy, well ive sorted it, cleaned out my tank and filters, and plumbing... even made a cage filter thingy for around my fuel pick-up pipe. there was a bit of gunk in the tank, think that may have been the problem.

took her out yesterday and she performed perfectly...

 

so again i say thanks to all that commented and gave me the advice i needed

 

ps im not going to mess with my advance/retard, it all seems ok and if it aint broke why try to fix it?

[Longboarder]

Having a loose vacuum advance plate will increase spark scatter from a dizzy, lucas or bosch. The mechanical advance is on the dizzy shaft. The two mechanisms are separate so fixing the plate shouldn't affect the mechanical advance. You are better with no vacuum advance than using vacuum from one runner only.

 

Nigel

[Bob Tucker]

isnt the A/R plate spring loaded in one direction?

[Longboarder]

Not always. Some are free to rotate and held only by the vacuum advance unit. When the operating arm of that begins to wear the plate can rattle. Long time since I examined a dizzy! Maybe I have forgotten the baseplate spring.

 

Nigel

Edited June 3, 2014 by Longboarder

[Guest coops222]

mine is held with a spring via the operating arm so its always held back untill vacuum is applied.

 

bloke from bogg bros has advised me that if im going to fit a plenum, only fit it to two inlet manifolds as four will make the vacuum too strong and will affect performance.