quadrajet vacuum line help - The 1947 - Present Chevrolet & GMC Truck Message Board Network

hobbz · 07-06-2005, 02:03 PM

please refer to the pics, do i have the vacuum line comming from the distributor in the correct place? the q-jet i took off had it on the other side of the fuel filter...

thanks for the help again

it is the middle one

71-longbed · 07-06-2005, 03:19 PM

take the hose off of the dizzy while the engines running .. if you can feel vaccum @ idle then .. that manifold vaccum ... if there no vaccum @ idle then that's ported ...

some guys run vaccum advance on manifold and some ported .. i like manifold myself

71-longbed · 07-06-2005, 08:54 PM

this might help .. although there refering to a 502

http://www.netwelding.com/ignition_timing.htm

Earl Filter · 07-06-2005, 09:36 PM

Mine is hooked to the vac line pictured above the fuel inlet, which looks capped. That one is manifold vacuum, which pulls vac even at idle. It doesn't seem to affect mine negatively.

SSC's76 · 07-06-2005, 10:39 PM

In all honesty it doesent matter. GM swiched to a ported source to lower emmisions @ idle, cheap but effective cure. Some engines run better off of a ported source usually the ones with small cams or engines that pull a good amount of vacuum @ idle. Engines with larger cams that dont pull alot of vacuum tend to run better off manifold "full" vac. Try them both and see which your setup likes.

07-06-2005, 02:03 PM	#1
hobbz Registered User Join Date: Jun 2005 Location: ashland, ky Posts: 632	quadrajet vacuum line help please refer to the pics, do i have the vacuum line comming from the distributor in the correct place? the q-jet i took off had it on the other side of the fuel filter... thanks for the help again it is the middle one

07-06-2005, 03:19 PM	#2
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	take the hose off of the dizzy while the engines running .. if you can feel vaccum @ idle then .. that manifold vaccum ... if there no vaccum @ idle then that's ported ... some guys run vaccum advance on manifold and some ported .. i like manifold myself __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

07-06-2005, 08:54 PM	#3
71-longbed Its Magically Delicious Join Date: Jan 2003 Location: oregon Posts: 2,398	this might help .. although there refering to a 502 http://www.netwelding.com/ignition_timing.htm __________________ 71 C10 LWB 350sbc -TH350 12 bolt 3.42 Posi Of all my favorite things to do, The utmost is to have a brew. My love grows for my foamy friend, with each thirst-quenching elbow bend. Beer so frosty, smooth, and cold it's paradise pure liquid gold. Yes beer means many things to me that's all for now cus I gotta pee.

07-06-2005, 09:36 PM	#4
Earl Filter Registered User Join Date: May 2005 Posts: 212	Mine is hooked to the vac line pictured above the fuel inlet, which looks capped. That one is manifold vacuum, which pulls vac even at idle. It doesn't seem to affect mine negatively. __________________ Real Name - Brandon Current Vehicles: 1977 C20 Silverado 454/TH400 3.73s 1989 Jaguar XJ6 in the middle of an LT1/4L60E swap

07-06-2005, 10:39 PM	#5
SSC's76 No No Join Date: Jun 2005 Location: Pueblo Colorado Posts: 1,781	In all honesty it doesent matter. GM swiched to a ported source to lower emmisions @ idle, cheap but effective cure. Some engines run better off of a ported source usually the ones with small cams or engines that pull a good amount of vacuum @ idle. Engines with larger cams that dont pull alot of vacuum tend to run better off manifold "full" vac. Try them both and see which your setup likes. __________________ 1976 Custom Deluxe SWB Med FMB.3/4 Drop. Gen VI 454, Muncie HD 3 speed With Modified OE Hurst Shifter, 3.73 12 bolt, GMPP HO roller cam, Hooker headers, Performer intake with modified Q-jet, Accel distributor. Best 1/4 12.3 @108. Funnest run 19.84 @88 full 1/4 mile burn out. 1997 K1500 ext cab 5.7 stock except muffler



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