Hi guys,

The idle on my car is tad too high. It's a 74 2.0 original injection. I recently installed Tangerine ss lines (and all rubber lines) and replaced a stuck fuel regulator (yes they can go wrong).

I have 2 bar fuel pressure and the car starts right up. Idle does not surge but it was at 1800 rpm. Replaced all vacuum lines and rubbers at the injectors. Took the AAR valve out and cleaned it. On start up the line from the AAR to the airbox sucks air, after 5 minutes or so it stops so I guess the AAR works as it should. New cork gasket under the oil filler.

Then and only then I touched the idle adjustment screw and idle is now at 1100 rpm. Idle adjustment screw turned by hand and not with a screwdriver. By hand it does feel that I'm at the end... can it go any further using a screwdriver ?

What else can I check or replace to get the idle at 900 rpm ?

Gasket under the throttle body ? Also noticed I have no rubber seal under the oil filler cap. As a test I zip tied a plastic bag over the oil filler cap but that made no difference. Noticed a small pinhole in the airbox (not the lid, the underside which attaches to the throttle body) which I taped off (better use jb weld or so ?).
The flange from the throttle body to the airbox seems ok but is a quiet hard.
The car has no decel valve and the connections at the throttle body are capped off - could it leak there - did not touch/change them yet.

Any further advise is welcome

thks
Dax

You have an air leak somewhere.

If the screw for idle adjustment is all the way closed then you would not have any extra air getting to the engine to keep it running. The throttle body does not allow enough air past it to keep the engine running at idle without a controlled leak from the idle screw.

Zach

It's real easy to make a homebrew smoke machine with about $20 of materials. A peanut butter glass jar (metal lid), cheap soldering iron, some tube, 5 minute epoxy, rag, bicycle pump (optional) and minerial oil.

Look for the many "how to" vids on youtube .

Ok will check youtube

First...I'd not run a stock D-jet set up without a decel valve. It puts excess pressure on the MPS diaphram and that can lead to problems.

Second...are you running the stock dizzy and did you inspect the advance plate throughly and check the vaccum pots for leakage?

That'd be my advice.

Yes, stock dizzy but intend to change to 123 ignition. Shall I first try to find the vacuum leak or can I install it right away ? Vacuum pots ... ? Sorry you lost me...

Krgds
Dax

There is a vacuum advance and retard (on some stock distributors)diaphrams on the stock distributors. These leak sometime ....usually...and will cause the sypmtoms you are experiencing. I'd test them (with a vac guage) to see and rule them out. I'd still get the 123...it was my solution to the above problem.

Run the decel valve....it matters.

A pair of incense sticks make a quick easy smoke test but watch the ashes or catch cup.

Advanced-retard plates in the distributor.

If no, remove all vacuum lines from the plenum, cover holes with duct tape.
If still idling high, it’s plenum itself or intake gaskets at head.

thks for all the help so far but here comes the question...
How to smoke test our cars ? Where to "inject" the smoke in the vacuum system ?
The line from the mps ?


thks
Dax

you are not injecting it into the intake.

You are laying a little smoke on the outside of the engine near seams that may leak and watching to see what the smoke does. Where you have a leak you will see the smoke get sucked in. If the area is sound the smoke just sort of sits there and swirls around.

Its safer then blowing propane at the seams and waiting for the engine to pick up speed to tell where its getting sucked in.

Make sense?

Zach

Okaaay... watched too many youtube vids where they all blow smoke in the system.
For your procedure I don’t need to make a smoke tester ... can use a vapor/e cigarette