General Category > Quadrajet Carb Talk and Tips

Modify 17080423 Quadrajet for use on 350 Buick?

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Cliff Ruggles:
Look at the gasket used between the baseplate and main casting.  On the non-CCC units the hole will show you where you need to drill to supply vacuum to the Power Piston.....

Jpn_Skylark:
With the gasket lined up as you say, simply drill straight through? I think I'm overthinking again but if I'm understanding correctly if drill straight through using the gasket as a guide the hole for the PP will be drilled on the edge of the manifold vacuum channel? Or would I have to drill at a slight angle?

Kenth:
I would keep the carb original since it´s a Turbo specific unit and simply place a hose as in my picture. No need at all for drilling.

Jpn_Skylark:
I hope Cliff clears up my confusion, but if I still have trepidation about drilling I'll likely go your route. Thanks

Cliff Ruggles:
Coincidentally I'm building the exact same carburetor in the shop for a FAST Class application.  It's going to end up on a 520CID Buick engine with ported Stage 1 heads and 13.6 to 1 compression.  Those carbs are easily up to that task and make excellent high performance street/strip carburetors.

I removed the vacuum fitting coming in from the front and melted some lead from a wheel weight into the hole instead then gently swaged it with a flat punch instead of permanently blocking it.   I then drilled the baseplate to supply vacuum directly to the power piston.  That hole could be easily blocked later, the lead removed and the stock vacuum fitting put back in place if the carb needed to be returned to the stock configuration. 

The picture Kenth shows is a quick and easy way to supply vacuum to the power piston without modifying anything if you don't mind using rubber vacuum hose across the front of the carburetor.......Cliff

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