General Category > Quadrajet Carb Talk and Tips

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Cliff Ruggles:
I would use a very fine punch and precisely locate the spot to drill.

Then drill it with a very small bit in a pin vise, around .030-.036".  Make another hole just to the right or left of it and drill another hole.  The factory actually did this with some baseplates when they slot wasn't used. 

If you are unsure where to drill find a baseplate already set up for ported vacuum advance and keep in mind that you are drilling at a slight angle and have to compensate slightly for it, so measure twice and drill once........Cliff

mcx:
...I think i can handle that...thx for the tip.   

Cliff Ruggles:
I think you'll be fine, a quick check with a vacuum gauge after it's placed in service will let you know how you've done.  It should have very little if any vacuum at idle, and FULL manifold vacuum with a very slightly movement of the throttle.

This is important as it basically provides the same strong vacuum signal to the advance that using manifold vacuum does, but without adding it at idle and coasting. 

Many engines don't like, want or need all that timing at idle, despite what you might read on the NET about that sort of thing......Cliff

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