69 GMC 402 Carb Vacuum Diagram?
 

Anyone have pics or a diagram for a 1969 GMC 402 Quadrajet 4Brrl with the vacuum lines? There is a vacuum port on the left side under the choke... trying to figure what that connects to? Thanks

Re: 69 GMC 402 Carb Vacuum Diagram?
 

Welcome to the forum!!
Take a pic of your carb.
Much easier for us to figure it out.

Re: 69 GMC 402 Carb Vacuum Diagram?
 

Usaly there are 2 small vacuum ports one for the transmissions vacuum modulator , the other for the ignitions vacuum advance , the last stock Rochester quadrajet I worked on , on a stock 69 c10 with a 350 , the one forward or closest to the radiator was hooked to the transmission , that is opposite of the way most holleys attach theirs , not positive that it came that way

Re: 69 GMC 402 Carb Vacuum Diagram?
 

Any advice on how to post a pic? Tried and it wants a URL. I took it w my phone. You must be able to upload somehow? Thanks

Re: 69 GMC 402 Carb Vacuum Diagram?
 

Re: 69 GMC 402 Carb Vacuum Diagram?
 

Here is a pic of the vacuum line under the choke. Thank youAttachment 1242475

Re: 69 GMC 402 Carb Vacuum Diagram?
 

That vac line is for vacuum to your charcoal canister which is located under your battery on the passenger side.
Here's a video that shows it. It's on a 71. I think your truck had one too.

Re: 69 GMC 402 Carb Vacuum Diagram?
 

I've looked through everything and all the lmc / classic industry parts and i do not believe my 69 2500 came with a charcoal canister. Any other ideas? I do believe this to be the original carb. Is it possible that line just had a plug on it?

Re: 69 GMC 402 Carb Vacuum Diagram?
 

Does your air cleaner have port for vacuum? If your truck is 69 it should be a 396.

Re: 69 GMC 402 Carb Vacuum Diagram?
 

What's the number on your carb?
First pic on here tells you where to look.
http://www.crankshaftcoalition.com/w...4MV_carburetor

Re: 69 GMC 402 Carb Vacuum Diagram?
 

Thanks everyone... I believe it is fur the vent on the air cleaner. I'm about 80% through the restoration and my air cleaner is missing the vent. Will post pics soon..this is going to be a sweet 69 resto mod.