Engine vacuum hose routing question - Pontiac GTO Forum
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post #1 of 7 (permalink) Old 09-23-2019, 10:51 AM Thread Starter
 
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Engine vacuum hose routing question

Hi Folks,

I have a 1970 GTO that was produced in Freemont, CA. As such, it came equipped with the Evaporative emissions package (special fuel tank and vapor canister). When I purchased it, I also bought the Service and Fisher body manuals on CD as well as the Assembly guide on CD.

The Service manual refers to this system in that it shows the special fuel tank, but only mentions the vapor canister in passing. Where the vent hose from the tank goes to on the canister is pretty clear as it's the biggest hose of the group and can only go to one of the nipples. However, the little IDs cast in the canister are no longer legible, and I don't think the previous owner had the rest of it hooked up correctly after the engine was rebuilt.

So, my question is: Does any know or have a picture of the proper vacuum hose routing between the canister and the engine with this California setup? I have scoured the Internet to no avail. Thanks.

Larry
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post #2 of 7 (permalink) Old 09-23-2019, 01:39 PM
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Here you go....this forum is so awkward trying to insert photos, I gave up a long time ago. Hope this works.
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post #3 of 7 (permalink) Old 09-23-2019, 01:42 PM
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A final attempt....[IMG]C:\users\FOJVIET\Desktop[/IMG]
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post #4 of 7 (permalink) Old 09-23-2019, 01:48 PM
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Larry, PM me and I'll try to email you a scan of the generic GM diagram. Basically, you have a line from the tank going to the charcoal canister, and a line from the canister to the carb vent, to absorb vapors from the carb. It should connect to the bottom of the air cleaner.
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post #5 of 7 (permalink) Old 09-24-2019, 02:02 AM
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Garage
Assembly Manual page 8-5.7.
Service Manual Page 6D-9


Although not entirely clear, by looking at both diagrams it appears that the center hose goes to the top of the carburetor float chamber.
The hose on the right (pass side) goes to the front of the carb at the throttle plate.

In 1970 the Evaporative Emissions system was a required option for cars sold in California or as an option elsewhere. Just because a car was built in the Fremont factory doesn't mean it had the Evaporative system, but since Fremont built the majority of cars for California it would seem that way. Other factories built cars with the Evap system if they were meant to be sold in California.

Ed


68 GTO (Thanks Mom)
70 El Camino SS
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post #6 of 7 (permalink) Old 09-30-2019, 05:45 PM Thread Starter
 
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Hi 052,

Thanks. I have both the service and assembly manuals. The 4MV section of the Fuel chapter actually has an illustration of the California QuadraJet showing the bowl vent connection. My car was originally equipped with the emissions pkg. My problem is that I know without a doubt that the carb is a non-correct, non-california carb.

I intend to do a Holley QuadraJet Sniper EFI conversion over the winter and will sort out the connections after I know what connections the throttle body gives me to work with.
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post #7 of 7 (permalink) Old 09-30-2019, 08:38 PM
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On my 70 El Camino one line taps into the PCV valve, the other goes to ported vacuum. (Small line with white stripe on the right of carburetor)
Maybe this may work for the Sniper.
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