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914World.com _ 914World Garage _ Vacuum Hose Layout

Posted by: gfg3 Jul 13 2016, 10:42 AM

I was checking through the layout of the vacuum hoses on my '75 1.8 and discovered that the PO had changed one of the connections from the decel valve. Picture below compares Jeff Bowlsby's standard diagram with my current setup. I have no EGR valve, no charcoal canister and no vacuum advance on the distributor, which is all fine. And, except for a minor cold idle problem, the car runs great.

Just curious whether the way the PO hooked things up makes any difference, or should I reconnect back to "normal"? Hey, if it's running fine I'm inclined to leave it the way it is. Thoughts?

Posted by: Mark Henry Jul 13 2016, 11:42 AM

How come no vac lines too the dizzy?

Posted by: gfg3 Jul 13 2016, 12:31 PM

QUOTE(Mark Henry @ Jul 13 2016, 12:42 PM)

How come no vac lines too the dizzy?

Not necessary. My dizzy is mechanical advance only. Car runs fine without vacuum advance.

Posted by: Mark Henry Jul 13 2016, 07:04 PM

Which dizzy?

Posted by: gfg3 Jul 14 2016, 07:19 AM

QUOTE(Mark Henry @ Jul 13 2016, 08:04 PM)

Which dizzy?

Dizzy is a Bosch 009.

But we're getting off track here. I have no problem with the dizzy. My question was whether I should change the vacuum line between the decel valve and the throttle body (bottom picture, the way the PO installed it) back to "standard", between the decal valve and the manifold (top picture). If it makes no difference, I'll keep it where it is since the car runs just fine. I don't know how all the vacuum taps look inside the throttle body and manifold.

Posted by: Dave_Darling Jul 14 2016, 05:25 PM

I believe that the way yours is set up now is that "ported" vacuum goes to the decel valve. What you want is manifold vacuum, from downstream of the throttle body.

--DD

Posted by: gfg3 Jul 15 2016, 06:01 AM

QUOTE(Dave_Darling @ Jul 14 2016, 06:25 PM)

I believe that the way yours is set up now is that "ported" vacuum goes to the decel valve. What you want is manifold vacuum, from downstream of the throttle body.

--DD

Thanks Dave. I'm not sure what the difference is as it would affect the decl valve, but I'll switch things back to the standard arrangement to see how the engine reacts. As I said, car seems to be running fine the way it is......maybe even better with the switch.

Posted by: gfg3 Jul 15 2016, 07:55 AM

OK, I found a chart that explains the difference. Thanks again Dave.