Vacuum advance

Post by **salty_monk** » Sun Apr 20, 2008 9:30 am

On the 62 falcon, the springs are buggered for the vac advance. plunger appears to work perfectly but when I opened it the springs stabilising the point plate were shot.

Here's one question... lots of misfires right now.. Would it be better to disconnect vac advance 100% rather than have it advancing at the wrong times?? If so should I try to lock it at zero advance or max advance??

Cheers,

Dan

Post by **bmcecosse** » Sun Apr 20, 2008 10:41 am

Vacuum adavance comes from a diaphragm - and a little spring on the spindle. You may be looking at the mechanical advance - which operates by weights flying out with centrifugal force, restrained by two small springs - which are not of equal strength. So while vac is important for economy and engine 'brightness', the mechanical advance is VERY important for good running. Is it a Lucas 25D dizzy ? They are normally very reliable - although sometimes the balance weights can stick. Just apply some oil and free them off - I've never known the little springs to fail!

Post by **salty_monk** » Sun Apr 20, 2008 7:10 pm

It's a strange setup... the whole plate with the points on it rotates. It has no weights on it but it does have 2 springs which appear to be equal...

I'll have to take some pics

Post by **salty_monk** » Mon Apr 21, 2008 5:57 pm

Huh... some more research, it's an "all vacuum" unit with no centrifugal advance, no wonder it looks weird!

Looks like I can get a recon one on exchange for about 40 notes.

Dan

Post by **bmcecosse** » Mon Apr 21, 2008 10:50 pm

Hmmm - very odd to have no mechanical advance. I would go with that exchange unit - especially if that's 40$ and not £40 ??

Post by **Kevin** » Tue Apr 22, 2008 11:07 am

Hmmm - very odd to have no mechanical advance

But not on a 62 Falcon perhaps.

Post by **bmcecosse** » Tue Apr 22, 2008 10:30 pm

On any engine - unless it's advanced 'electronically' of course - needs the ignition timing 'mapped' to the rpm at the very least! Consider the Minor engine - say 5 degrees at idle - but advancing mechanically by another 28 degrees or so when running. A Minor engine with the mech advance seized up is a v flat and gutless thing!