Weird fast idle problem? Urgent!

[Catalyst07]

Hi everyone - recently picked up an early 912 with Webers-- was driving the other day and all of a sudden the idle started to raise up when in neutral/clutch in. My tach doesn't work but probably to the 3000-4000 rpm range.

I pulled over, shut off the car and inspected the linkage from the gas pedal to the carb linkage - everything is tight and looks good. I can fire it up, walk back to the engine and watch the RPM's increase to 4k while the throttle levers are fully pegged to the idle adjustment screws on both Webers.

Upon further inspection, the rear most passenger-side Weber jet doesn't squirt any fuel when I move the throttle lever with my hand. The other 3 do and look good. Could this be the idle problem?

What's the best way to approach this? I just want it to run properly... Located in Palo Alto

[Jaems]

First of all you will need to clean the jet so they are all working.

Since you have just purchased the car. You may have not done a tune up on the engine. You first need to adjust the valves. 912's do not run well unless the valves are adjusted. Check and if needed, replace the points and set the dwell. Then set the timing a static time to start and then 30-35 degrees at 3100rpms.

Once you have do this, then adjust and sync the carburetors. The linage has to be off the carburetors while doing this. Once the carburetors are synced and adjusted. Then you adjust the linage by screwing the ball caps so they will fit the carburetors without changing the carburetor adjustments.

If'n any of the adjustments are off, especially the valves. The 912 engine will not be very happy and not give you a smooth performance.

Most people that have had problems with the Webers are the ones that have never had them sorted out for the 912 engine. If'n you are still having idle problems. Then the carburetors will need to be rebuilt. Or your Webers may have never been sorted out for your engine. They came originally sorted for the VW engine. If you still have the 28 venturi's. Then it is a good chance that they have never been sorted for your engine. The 32 venturi's are needed for the 912 also stacks are needed for a engine running under 6000 RPMs. They only work on racing engines that are turning 6000+ RPMs on the race course.

[Peter Graham]

+1 for Jaems. You should also look at the distributor advance mechanism: the advance can stick or in combination with a high idle, start to advance where it keeps driving up the RPMs. It would also be helpful to know which distributor you have on the car. The 009 is definitely the wrong curve for the 616 motor.

Peter

[JT912]

If you pop off the linkage at each carb, does the idle drop? I once had a car that had the same problem, I backed off the idle screw and it still screamed. I popped of the linkage and found there was a bent throttle linkage which was preventing the carbs from returning to idle.

[Jaems]

There are only 4 distributors that will work with the 912. The 022 which originally came with the car. The 031 which is for high performance. The 061 which was original for the 68 with a vacuum retard advance. The RS0012 which is a recurved 009 to best fit the 912 advance. You only want the original German made 022, 031, and 061. The Chinese versions of these are crap.

The stock 009 and the 050 are designed and curved for the VW. They will work in a pinch, if they are the old German ones, but not with good performance. The newer Chinese and Brazilian ones are crap.

[JT912]

Keep in mind the distributor type will not inherently cause this problem. Fast idle can be sticking advance as mentioned or even possibly the entire distributor has turned just enough to raise the idle, but not so much as to cause a problem. Have you tried to rotate your distributor? You shouldn't be able to turn it by hand.
I doubt your fuel issue is related to an increase idle problem, especially since it appears to be a lack of fuel.

[Catalyst07]

Thanks for the responses guys - dug into it a bit more today and this is what I found:

I don't think the passenger side cylinders are firing? In addition to the passenger side fuel jet not squirting when the throttle is opened, I can take my hand and cover the passenger carb and it doesn't stall or choke out at all. I can't feel any vacuum from the rear most port, and only a little from the front one. The drivers side has a very strong suction when I put my hand over the carb.

Checked the dist and it's stamped 009.

The motor was rebuilt about 4 years ago, and I think it was a bigger bore/performance rebuild because even as it is, the car feels like I has a lot of power (I've had many 500hp cars and this 912 is not as anemic as I imagined, even how it's running now).

I think the safe way to handle this is to have someone rebuild the carbs, adjust the valves, go through dist/timing, and then reinstall/sync the carbs.

I would do this myself but I don't have a garage/tools right now. How much would something like this run? I really need to get it drivable again

[Catalyst07]

Forgot to see if I can turn the dist by hand- will try that tomorrow

[Jaems]

The 009 can be recurved to fit the 912 engine. It is done by John Benton. It will then be a RS0012 and one of the best replacement Distributors for a 912 engine the only better one is the 031. However the cost difference is about three times. The 009 is only good at 5000+ RPMs. Your low end will be poorer.

Find someone, in your area, that really knows Webbers. Once they are sorted out, they will really surprise you. The 912 will not dump you in the back seat, from a standing start, like a Mustang, 911, or etc. Their acceleration is very subtle. Without realizing it you can be doing 80mph. The cams don't come on until 4K rpm, and they love it there. Keep the engine above 3K rpm anything below that will be lugging it. This is with a stock 912 engine.

A passing note: I had my Webbers rebuilt in 2000, my engine rebuilt in 2004. I have had one adjustment on the Webbers in 2008 when they change the gas in my State to 10% alcohol. I lost the idle. Since then and before that date. I had not had to touch them.

I can let my car sit for 6 months. Jump in and turn the electric fuel pump on hit the starter a few short times to get some oil around the engine. let the fuel fill up the bowls and pump the gas a couple of time and it will start, saves wear and tare on the battery and the starter. I have a pointless 031 distributor and have not had to do a tune up for 14 years. I just check the valves when I change oil and filters.

Good luck and enjoy sorting your engine out. Once it is done, you will love driving the most forgiving Classic Porsche ever made. It may not be as quick as a 911. However, you can do every thing a 911 can do, except you don't have to do it as fast.

[Kaizer]

Been dealing with the same issues on my 912.

Between Jaems, JT and Peter - You're in good hands with three of the best here offering advice.

I've found their tips/advice/insight to be invaluable as I work to get mine back in line too.

Good luck!

[JT912]

Can you post any pictures of your carb linkage setup? I understand Webers have some modifications to the stock Solex linkage. Maybe Jaems can spot your hang up.
So to get this straight. Your car ran fine in the short time you've owned it.
Out of the blue, it began idling much faster than normal. (Does it seem to level off at some point or does it seem like it will continue until engine failure speeds are achieved?)
This idle situation occurs both with the clutch in and when the car is in neutral and the clutch is out.
Have you tried oiling the felt in the top of the distributor shaft?

[Catalyst07]

John, sure - I will take some pics later today and post them up.

It seemed to run fine in the short period I had it, but bear in mind that I've never driven another 912 to compare it to.

While driving on the highway, and entering stop and go traffic, I noticed the idle suddenly wanted to idle really high, so I pulled over, looked over the linkage, etc and couldn't find the issue so I just drove it home by downshifting through the gears and double clutching a lot for stops.

Once home I discovered the one squirter was clogged, and the throttle return springs weren't bringing the levers to the throttle stops, so I adjusted the linkage. But, even with the linkage disconnected, it still idles high when I peg the levers to the idle screws...

I haven't removed/cleaned the fuel jets yet but at this point, since it's my only car, I'm of the inclination to just have it towed to a porsche expert and gone through valves, timing, carbs.

I'm hoping I can get this squared away for less than $500, or even better, that it's something simple I can do with my hand tools

[WFBowen]

As JT and Peter suggest above, a good starting point for this problem is the distributor advance mechanism. First make sure the dist. is firmly clamped in position. Then pull the dist. cap and twist the rotor against the tension. It should snap back repeatedly to its starting position. If it feels mushy or seems to hang-up then the advance is causing the problem. Sometimes one of the small springs breaks or comes off of the weights or the whole mechanism is just clogged with dirt and old grease. Either way, shoot a little carb cleaner through the advance plate while moving the rotor shaft. Then spray some WD40 in there and put some oil on the fiber material under the rotor on the shaft.
If all of this checks out, look for a vacuum leak on the "dead" side.

[Jaems]

There will not be any Vacuum leaks on a 022, 031, 009, 050 or RS0012. They are mechanical not vacuum advance distributors. Only the 061 had a vacuum retard advance.

[Jaems]

A tuneup can be done in a couple of hours. oil and filter, valve adjustment, replace points, rotor and cap, and set the timing.












The linage on Webers

[Scott Douglas]

I think he (WF) means look for leaks around the carbs/cylinder bank that isn't firing Jaems.

How are you my friend?

[WFBowen]

Scott :
That's exactly what I was referring to ... I should have been more specific.
Bill.

[Catalyst07]

Ok, didn't get a chance until it was dark out, but I popped the cap off the dist and here's what it looks like:

Does it look normal to you? Looks like it's touching to me, and not sure what springs you're talking about (if you mean timing advance springs like my old mustang, I didn't see any?)

[JT912]

If you pull off the rotor, there should be a little felt pad in the center of the shaft. Put a few drops of oil on it. Put the rotor back on and try to turn the rotor clockwise. It should rotate just a bit then snap back. There are a set of plates, weights and springs that control the advance. If it is sluggish to return, that might be a reason for your idle problem.

[JT912]

009 distribtutor