Vacuum advance and pluse generator (VACUUM ADVANCE REBUILD)

[dan filipi]

Thanks again beav, good information.

I tried marking the cam pulley like that but the mark was all over the place.
It would steadily move away from the mark then repeat the cycle so I found it wasn't a reliable timing mark.
Does it stay in one spot for you?

 

[danf]

Thanks again beav, good information.

I tried marking the cam pulley like that but the mark was all over the place.
It would steadily move away from the mark then repeat the cycle so I found it wasn't a reliable timing mark.
Does it stay in one spot for you?

Mine looked steady, a friend told me about this, and I tried it, I held it on there and didn't see that moving around your talking about at idle, I will try it again to double check it ..

 

[dan filipi]

Well I'll be!

I'll have to try that again.

 

[joedrum]

it would seem that the timing was jumping around ....it all hooked together ...it would have to read right if the belts and all are hooh up right ....if not its telling you that somting is drasticly changing the timing .....weak wires , coils , ballist , cdi units and rough running cause machanical advances to stutter back and forth because of uneven centifical force..... and also vacume shutter from rough and uneven pulses :mrgreen:

 

[dan filipi]

I would think the mark would stay in one place also, that's why I tried it.
Like the 205 compression I can't explain it.

The mark doesn't jump around.
It would progressively and smoothly move away from a point then repeat the cycle from the same starting then the same ending points.

 

[danf]

Well I'll be!

I'll have to try that again.

Have you had much luck thru the site hole with the light? Can you see it thru there? ......................

 

[joedrum]

thats sounds right to me dan i thought it was wildly moving around ...that last comment sounds like the advance spread :mrgreen:

 

[dan filipi]

I did try it thru the site hole a long while back and could see my mark but it was difficult.

I had modified a oil filler cap for a site glass but now the plastic I used is foggy and impossible to see thru.

Draining the crankcase oil down to add seems to help some to reduce the oil wash.

 

[dan filipi]

thats sounds right to me dan i thought it was wildly moving around ...that last comment sounds like the advance spread :mrgreen:

If I had been revving then it would make sense but the mark moves at a steady idle.

 

[scdmarx]

If I had been revving then it would make sense but the mark moves at a steady idle.

First, make sure your idle is low enough not to be trying to activate the vacuum advance. Maybe even unplug the advance hose when checking timing.
At idle, as the timing advances, the RPM should go up.
If the RPM is not changing when this happens, I think you might try a different timing light. Sometimes it's just a simple matter of the equipment and system compatability.
I know, it sounds korny, but it happens.

You could use a 12v test light connected to the neg. side of the coil. This won't be as convenient as an inductive light, and you may have to dim the lights to see.

 

[danf]

Dan, we just double checked it again and the timing marks are right on the paint marks and didn't move around at all I watched it a good minute or two just to make sure.. steady, the pulley mark went up when I had my daughter throttle it,vacuum hose on it and all..Wow..Are your marks staying together when they move or are they separating all together and all over..?

 

[joedrum]

im not real sure yet but there is a mechanical advance on the 1100 also :mrgreen:

 

[dan filipi]

..Are your marks staying together when they move or are they separating all together and all over..?

The mark steadily moves off, strange.

I have had timing lights do strange things like this, even had one that flashed randomly putting the mark nowhere near where it should be. Maybe that's it.

 

[danf]

..Are your marks staying together when they move or are they separating all together and all over..?

The mark steadily moves off, strange.

I have had timing lights do strange things like this, even had one that flashed randomly putting the mark nowhere near where it should be. Maybe that's it.

didn't you say your vacuum advance was leaking? Dan how much is it moving or traveling away? 1/4" or what? If this thing moved on me I sure didn't see it..Sounds like yours was pretty noticeable... I still think it's best to try to read it from the site hole some how..Better that kind... :smilie_happy:

 

[slabghost]

incorrect spark timing can definitely cause a knock. Have you checked the plug wires in the dark? Running in the dark and look for stray sparks?

 

[danf]

incorrect spark timing can definitely cause a knock. Have you checked the plug wires in the dark? Running in the dark and look for stray sparks?

No the knock is gone now is what I'm saying, it was there before I fixed and cleaned up the mechanical and vacuum advance..Gone gone gone,,, cool beans man..It was a noticable knock too, I was really worried about it..I just wish I knew which one cured it..my guess is the mechanical advance...

 

[dan filipi]

didn't you say your vacuum advance was leaking? Dan how much is it moving or traveling away? 1/4" or what? If this thing moved on me I sure didn't see it..Sounds like yours was pretty noticeable..

Yes the vac advance is leaking.

The mark moves a good 3-4 inches while staying at the same rpm.
It moves just like if you were rotating a distributor, then back to it's mark then rotate it again over and over.

 

[slabghost]

Sounds like it's time for da beaver mod! :smilie_happy:

 

[joedrum]

seems like a sticky slow moving advance that stuggleing to operate at the speed it needs to ....who knows this may be the cause of a lot of the problems in its running .....im going to go outside now and try to work on mine ...maybe i can come up with something :mrgreen:

 

[danf]

didn't you say your vacuum advance was leaking? Dan how much is it moving or traveling away? 1/4" or what? If this thing moved on me I sure didn't see it..Sounds like yours was pretty noticeable..

Yes the vac advance is leaking.

The mark moves a good 3-4 inches while staying at the same rpm.
It moves just like if you were rotating a distributor, then back to it's mark then rotate it again over and over.

Oh my, I thought you were gonna say 1/8" or so..man Dan, It probably has something to do with the cam change I bet..