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Hamish

TR3A vacuum advance.

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Question. 

To test if this is working can one suck on the pipe and make it operate ?

or does it require a greater vacuum than mere man can provide ? 

H

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Hi Hamish ~

I've used the 'suck' method to test the vacuum advance. I suggest that you contact Distributor Doctor for advice.

Tom.

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If you have a timing light,first check without vacuum then with , you will see the timing change proving vac unit

is working.

                                   Harvey S. Maitland

 

                                                                  

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47 minutes ago, Hamish said:

Question. 

To test if this is working can one suck on the pipe and make it operate ?

or does it require a greater vacuum than mere man can provide ? 

H

Yes remove the dizzy cap and suck on the pipe and you should see the baseplate move. stick your tongue over the end and it should hold its position, if not the capsule is inoperative and needs replacing. Most racers tend to delete it anyway.

Stuart.

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Thanks Stuart. Tom 

Thats a no for me then !!

i’ll pretend I’m a proper racer then :blink:

Harvey. 

I am trying to work out my timing. That lead me to the vacuum.

i have the cam chain cover pointer marked up.

i also have the ali narrow belt crank pulley marked up to show tdc on piston position and rocker cover off  with 12 thou on piston one valves, 

this has been the set up for years and on a rolling road  

but the timing light strobes when running - showing the crank pulley mark to the RIGHT of the cam chain cover pointer.

car seems to run very well, I don’t understand it :wacko:

 

Edited by Hamish

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Is that standing in front of the car looking rearwards? If your seeing the TDC mark to the right of the pointer on the strobe then thats correct as you should have about 4degrees of static advance at tickover with the vacuum line disconnected.

Stuart.

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It is as you describe. 

But I don’t understand why?

(it’s me being thick)

but the crank rotates clock wise  ?

if the marker is to the right isn’t that on the downward stroke after tdc ?

 

( ooo. The forum platform has changed too !!!)

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Hamish

                  If this helps assume 10" BTDC mark on pulley (to the right viewed from front) is opposite pointer on front cover

with ignition firing, this is  before the TDC mark on pulley lines up with pointer , hence timing is set at 10" BTDC. Hope this

makes sense.

                                                           Harvey S, Maitland

 

 

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this helped me understand from about 55s in. 

I better understand how the circular motion of the front pulley translates to the piston stroke and thus the advance of the spark. 

I now have fitted my electronic ignition module. The car starts and appears to run smoothly. I need to road test it tho.

thank you for trying to help this numpty. 

h

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