Vacum hook up for carb and smog pump

Tiny
BRAD G
  • MEMBER
  • 1976 GMC SIERRA
  • 90,000 MILES
Can you direct me to or provide the diagrams I need to re tube the vacuum correctly? Smog test tech told me I was missing two hoses for smog pump and carb was hooked up to vacuum wrong and didn't do the smog test. The Chilton book does not have a very good diagram for either 1976 carb or smog system and I don't know how to determine what the lines should connect to what ports. The carb is the Rochester Quadrajet 4MV on a 350 engine with HEI Distributor. Timing is set to 6 BTDC and it idles about 800 rpm until I disconnect the vacuum advance and plug it, then idle drops and it runs rougher. I need it to pass California smog. There is no emission sticker in the engine compartment that I can find. Any help or direction would be appreciated. Your site was recommended to me by my son in law who got help with his 68 Impala. Thanks
Monday, November 18th, 2013 AT 5:36 PM

1 Reply

Tiny
HMAC300
  • MECHANIC
  • 48,601 POSTS
I am going to assume this is a 350 youneed to know if it's a federal or California and if you have a diverter valve or not. Diverter valve is for an air pump there will also be a vacuum valve leading ot exhaust manifold on rh bank.
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Tuesday, November 19th, 2013 AT 6:20 AM

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