Frank75

I don't have any way to post a picture, but on my Q-Jet ('75) I can push the secondary air valves wide open at idle. The rod attached to the front vacuum-break diaphragm (that looks like it should hold the valves closed) does not do so. I don't think this is right! :confused: You can push on the rod and the spring slowly pushs the rod out again. There's a bleed hole mentioned somewhere and quite honestly I don't know if I'm putting vacuum to the right place to pull the thing closed. The carb's been rebuilt and I put everything back after replacing hoses. A lot of the emission equipment has been removed from the car by previous owners.

It's hard to find out which vacuum lines are supposed to go where and this particular valve is currently fed from a port that's near the top of the carb. Where's the best source of info on this? Can't find it in Doug Roe's book, any of Lars' excellent papers, etc. Does the AIM show this (I don't have one unfortunately)?

Thanks for any help. :D

Frank75

Anyone?

comp

bump ya' up

Frank75

Thanks Comp. I bit the bullet yesterday p.m. and ordered one from the local Chevy dealer ($34). I know it's got to be wrong but was looking for someone to hold my hand before shelling out for the part. I'm just a natural tightwad I guess. :rolleyes:

comp

i can't get outside right now, but i'm pretty sure in needs to be connected to manifold vac. source.. hey new ,shiny parts :thumbs: :hurray:

sjr1971

I downloaded a pix from either corvette forum or faq a while ago. Any way you have 2 ports on the Q-jet that are ambiguous. Same size. I had my carb re-built by the last folks that still do it in my area. The driver's side port [viewed from the front of the car}is a metered vacuum port and goes to the distributer, the port on the passenger side goes to the vacuum tank. Don't think this is your problem but these are the hook ups

Frank75

Thanks for the info. This carb has some ports on the passenger side near the top of the carb body. They have some vacuum on them at idle; I haven't put my vacuum gage on it yet but I think it's from the manifold. One of those went to some emission stuff I think and the other to this knockoff diaphragm.

Last Place

This may be of some help: https://www.corvetteforum.com/techti...D=86&TopicID=3

Frank75

Excellent! Thank you so much! That shows exactly what I need. The choke pulloff was hooked up OK but now I can verify the other lines as well.


[Modified by Frank75, 1:08 PM 2/15/2004]

duntovlives

after you get your new pull off installed, be sure and check to ensure your secondaries open at your preferred time. you can adjust it w/ a 3/32 allen wrench and a pocket screwdriver. there is a spring around top set of flaps (the ones that raise the metering rods) u can adjust the tension and get it "just right" .... if they open too soon, u get a dead spot.... too late, and u dont get the full cfm when u want it. check it w/ your breather installed while making adjustments.

also, check to ensure there is vaccuum present at the port that feeds the pull-off. make sure it is not blocked.

good luck, and happy four-barreling :thumbs:

Frank75

Thanks for the tips. I've already made sure I know how to get to that adjustment and tweaked the secondary opening per Lars' recommendations. I also rejetted during a rebuild to allow for headers and dual exhausts. This is the last of the ****ling problems (I hope). I'm starting to get excited as the car has been off the road for almost 4 years while I rebuilt suspension, brakes, fixed the frame, painted, new interior, did household projects, etc. etc. It had sat for about 3 months before I went out last week: gas pedal to the floor (I got the cold air door working too!) it cranked about 3 times and fired right up! :cheers:

Come April I'm going to be on the road again, fer sure. :yesnod:

comp

:cheers: let us know when you air it out :thumbs: