QJet Help!
Thread Starter
Team Owner
Joined: Mar 2002
Posts: 24,160
Likes: 78
QJet Help!
Can someone please tell me the correct routing for the three circled and numbered ports here? When I got the car, one of them was routed out to the port in the waterneck (for the heat riser system I think?) and the other two were routed to each other (choke?). But I can't remember which was which, and I don't even know if it was right when I got this thing. (the hoses were rotted and fell apart in my hands)
TIA :flag
TIA :flag
Tech Contributor
Joined: Aug 1999
Posts: 14,379
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: QJet Help! (wcsinx)
Your choke pullof has been disconnected - you're missing a hose. This must be creating a horrible rich condition on startup (if your choke is working), and it will produce a bog going into the secondaries. Pull the cap off the choke pulloff and attach a hose to it: Suck on the hose and verify that the pulloff retracts correctly and that it holds vacuum. If not, replace it. If it works, run a hose from the pulloff to the one vacuum port that is closest to it (you have it circled). The vacuum port on the front of the carb is manifold vacuum, and can be used for emissions accessories.
Pro
Joined: Nov 2002
Posts: 599
Likes: 16
From: vista CA
Re: QJet Help! (lars)
Your choke pullof has been disconnected - you're missing a hose. This must be creating a horrible rich condition on startup (if your choke is working), and it will produce a bog going into the secondaries. Pull the cap off the choke pulloff and attach a hose to it: Suck on the hose and verify that the pulloff retracts correctly and that it holds vacuum. If not, replace it. If it works, run a hose from the pulloff to the one vacuum port that is closest to it (you have it circled). The vacuum port on the front of the carb is manifold vacuum, and can be used for emissions accessories.
just get several inches of hose from your local auto parts store - short one to connect the two on the left. one on right goes to the smog pump diverter valve and EFE on my 79...
Team Owner
Joined: Jun 2001
Posts: 23,375
Likes: 1,067
From: Virginia USA
Re: QJet Help! (martinsw)
Pictures are worth a thousand words....check here https://www.corvetteforum.com/techti...D=86&TopicID=3
Burning Brakes
Joined: Feb 2004
Posts: 958
Likes: 1
From: In the Beautiful Shenandoah Valley of VA
Re: QJet Help! (wcsinx)
Maybe. As pointed out above, the primary choke pull off also controls the opening rate of the secondary air valve (the big one on top of the secondary barrels). Without the pull off working properly, you could also have a serious bog problem when stomping on it. If you aren't having any cold running or hard acceleration problems, you can leave it alone. Before you connect a (short) vacuum hose between the port and the pull off though, verify that the pull off holds vacuum. Note that some of these pull offs are controlled bleed-off style, which means they won't hold a vacuum unless you cover the bleed hole (in the front) with a piece of tape. If no hole, it's not a bleed-off type.
Burning Brakes
Joined: Oct 2001
Posts: 842
Likes: 3
From: Woodruff SC
St. Jude Donor '10
Re: QJet Help! (wcsinx)
I've been told if you plug the two on the left of your pic, the carb will react like mechanical secondaries rather than vacuum. Don't know how true but, you can tell a difference.
I'd like to know what LARS thinks about what I've said. True or not??
But, IMO, run a hose between them, runs a little smoother plus better gas mileage.
I'd like to know what LARS thinks about what I've said. True or not??
But, IMO, run a hose between them, runs a little smoother plus better gas mileage.
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