School me on L-Jet, 2 questions for an L-Jet newby Options

[ClayPerrine]

Here is the simple answer:

If your L-Jet throttle body has two vacuum fittings, hook them both up to the distributor as the diagram shows.

If your L-Jet throttle body has only one vacuum fitting, hook it up to the retard port.

['73-914kid]

Thank you.. the throttle body has a plugged port on it. Hooked it up, and the idle dropped to about 750 RPM at idle, and now doesn't stick on it's way down once it's hot either.

[Cap'n Krusty]

I guess I failed in my attempt to clarify the port thing. Yes, all 1.8 L-jet 914s use vacuum retard. Some, especially early models, also use vacuum advance. If the TB has no vacuum advance port, then it doesn't use it. If it's there and plugged, unplug the sucker and connect it as it was meant to be. If there's a way to misinterpret what I say, someone will find it. BTW, you not only remove the vacuum line(s) to set the timing, you also plug them for the duration of the process.

The Cap'n

[Porschef]

My throttle body has no provision for an advance hose to the dizzy.

I'm wondering if'n it would behoove me to drill out the body downstream of the plate and run the line (purple in diagram)

This may allow for a small retard in static timing ?

Still trying to balance mixture and head temps. AFR gauge and manual diddling of the static arm in the AFM says engine wants to be more lean. Head temp says "I wanna be rich"

[nihil44]

So, if you remove the decel valve, where does the vacuum plumbing go?

The decel valve has 3 ports with lines to:-

- to fuel pressure regulator

-to air distributor (also called plenum chamber?)

-to rubber intake boot between air flow meter and throttle body

How does one manage each of these lines?

Would appreciate an authoritative response. My 1.8 is demonstrating petulant behaviour at present and needs some firm parenting

Thanks

David

[timothy_nd28]

Buy some of these and have at it

[nihil44]

Timothy,

Thanks for your response but I couldn't see what the product was from your photo and what is its purpose.

Would appreciate more info, particularly how the lines from the decel valve are dealt with

Thanks

David

[Tom]

Rubber nipples to cap off vacuum line you don't want to use anymore.
Tom

[nihil44]

Which ones are no longer in the vacuum circuit?

Does fuel pressure regulator require vacuum? etc

Would appreciate some clear explanation


David

[Dave_Darling]

The L-jet fuel pressure is referenced to manifold pressure. So the FPR does need a vacuum line to it from the manifold.

The Decel Valve is an intentional way to let air go from in front of the throttle valve to after it under some circumstances. (In the D-jet world we call it an "intentional vacuum leak", but in L-jet it lets air that has been measured by the Air Flow Meter go in, so it's not really a leak.) If you remove the DV, then you just plug the fittings that used to be hooked to it.

What exactly are you asking for a clear explanation of? Everything in the vacuum system? Just a few specific bits?

--DD

[nihil44]

Dave,

Thank you for your reply and satisfactory explanation. I will bypass the valve and hope there is a resolution of the misbehaviour

David