L-Jet Idle on new build with 9550 Options

[andreic]

Hello,

I am just finishing up a new engine build for a 1975 914 1.8L.

The engine is mostly stock, except for the fact that I am using 96mm cylinders (1911cc total) and a Raby 9550 cam. Using the stock L-Jet fuel injection.

I managed to get the engine started, broken in (25 minutes at 2500 RPM), all is well. I also adjusted the timing as per standard instructions (showing the L-Jet mark on the fan at 800 RPM with vacuum lines removed and plugged). The engine is accelerating smoothly and seems to have good power throughout the whole RPM curve (without a load, though, I am testing it outside the car).

The only thing not working is the fact that it will die (stall) at idle. Does not matter if it is hot or cold. I tried the idle adjustment screw on the throttle body, and while I can perhaps get the idle up to 500 RPM with the screw all the way out, I can't get it to 900. And at 500 RPM it is very shaky.

Any suggestions as to what I can do? I knew that using the 9550 cam with the L-Jet was going to give me trouble, but I hope there is some way to fix this. Tomorrow I want to check if there are any vacuum leaks, but I suspect there are none, I was quite careful with all the vacuum lines. If the problem is the cam, can the throttle be perhaps modified to let in more air at idle?

Thanks,
Andrei.

[catsltd]

The exhaust valve clearence on a 1.8 is .008 according to the late great Cap't Crusty and intake is .006.

Nope. I believe that the Cap'n retracted that. It comes from one particular source that is wrong. The 0.006" is correct for both intake and exhaust on a 1.8, as well as for a 1.7, and even the intake on the 2.0 engine. The only place for 0.008" clearance is in the sodium-cooled 2.0 exhaust valve.

--DD

I had timing issues with my 1974 1.8L and valve adjustment problems as well.

I finally timed it myself.(Red mark on fan housing line up to v grove.(800 RPM)Must use Red timing mark.

Then adjusted my valves by Captain guidelines,and now car runs perfectly,never had a better idle.Just did it today,so friggin happy.Hope you figure it out.

[pete000]

The exhaust valve clearence on a 1.8 is .008 according to the late great Cap't Crusty and intake is .006.

Nope. I believe that the Cap'n retracted that. It comes from one particular source that is wrong. The 0.006" is correct for both intake and exhaust on a 1.8, as well as for a 1.7, and even the intake on the 2.0 engine. The only place for 0.008" clearance is in the sodium-cooled 2.0 exhaust valve.

--DD

(IMG:style_emoticons/default/agree.gif)

[pete000]

After all this the engine ran better, though not perfect. I can get it now to idle at about 500 RPM (the needle on the tach barely lifts up)

My friend, this is not 500

I recommend using the tachometer on the timing light if yours has one. My 914 Tach seems to be a bit off compared to the tachometer in my timing light. (914 tachometer reads a bit fast on my car)

[Big Len]

The exhaust valve clearence on a 1.8 is .008 according to the late great Cap't Crusty and intake is .006.

Nope. I believe that the Cap'n retracted that. It comes from one particular source that is wrong. The 0.006" is correct for both intake and exhaust on a 1.8, as well as for a 1.7, and even the intake on the 2.0 engine. The only place for 0.008" clearance is in the sodium-cooled 2.0 exhaust valve.

--DD

You are correct...thanks, Dave.

[andreic]

Bump on my main question: should I increase the idle by removing the idle retard line (and capping it off) or by advancing the timing? How important is the idle retard line (I know that some L-Jets don't have them).

[914_teener]

Bump on my main question: should I increase the idle by removing the idle retard line (and capping it off) or by advancing the timing? How important is the idle retard line (I know that some L-Jets don't have them).

Have you checked the retard and advance diaphragms for leakage that are on the dizzy?

Go to HF and buy the vacuum gauge if you don't already have one and test them to make sure they are not leaking.

Otherwise you have another vacuum which could be causing the problem.

My .02