Mystery Screw on Quadrajet! - The 1947 - Present Chevrolet & GMC Truck Message Board Network

savatreatabvr · 02-09-2012, 06:04 PM

Can anyone tell me what this screw does? Its a Quadrajet 17057213.

rs72z · 02-09-2012, 06:43 PM

I could be wrong but it looks someone plugged a vacuum port.

**Corts60** · 02-09-2012, 07:13 PM

I agree with rs72z. There is definitely nothing to adjust there.

savatreatabvr · 02-09-2012, 07:13 PM

You may be right because I tried turning it and it wouldn't budge!

Quote:

Originally Posted by rs72z

I could be wrong but it looks someone plugged a vacuum port.

ray_mcavoy · 02-09-2012, 07:39 PM

According to the Rochester Carburetor book by Doug Roe, that's the early form of the APT (adjustable part throttle). The screw adjusts the lower stop for the power piston. That screw was normally adjusted at the factory and then covered with a little press-in plug. The later Q-Jets have the APT system in the fuel bowl.

02-09-2012, 06:04 PM	#1
savatreatabvr Registered User Join Date: Oct 2011 Location: phoenix, az Posts: 508	Mystery Screw on Quadrajet! Can anyone tell me what this screw does? Its a Quadrajet 17057213.

02-09-2012, 06:43 PM	#2
rs72z Registered User Join Date: Oct 2011 Location: Emory TX Posts: 900	Re: Mystery Screw on Quadrajet! I could be wrong but it looks someone plugged a vacuum port.

02-09-2012, 07:13 PM	#3
Corts60 Just here to tinker Join Date: Jun 2008 Location: Holland, MI Posts: 3,697	Re: Mystery Screw on Quadrajet! I agree with rs72z. There is definitely nothing to adjust there. __________________ 78 C10 SWB Diesel #1 (wrecked)http://67-72chevytrucks.com/vboard/s...1978+silverado 78 C10 SWB Diesel #2 (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=650751 60 GMC Suburban (sold)http://67-72chevytrucks.com/vboard/s...d.php?t=445526 60 GMC 1000 (sold)http://67-72chevytrucks.com/vboard/showthread.php?t=298235 67 GMC 1500 (sold) http://67-72chevytrucks.com/vboard/s...d.php?t=803695 73 Chevy C20(Daily)http://67-72chevytrucks.com/vboard/s...d.php?t=852767 86 Suburban(summer unit) http://67-72chevytrucks.com/vboard/s...d.php?t=810697 88 Suburban 4x4(sold)

02-09-2012, 07:39 PM	#5
ray_mcavoy Registered User Join Date: Nov 2009 Location: Sherman, ME Posts: 2,366	Re: Mystery Screw on Quadrajet! According to the Rochester Carburetor book by Doug Roe, that's the early form of the APT (adjustable part throttle). The screw adjusts the lower stop for the power piston. That screw was normally adjusted at the factory and then covered with a little press-in plug. The later Q-Jets have the APT system in the fuel bowl.

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode



Register or Log In To remove these advertisements.

Register or Log In To remove these advertisements.