Fast Idle. (Very fast idle)

h.beard · 06:52 PM

Great board. I'm the proud owner (new) of a 69 912 black plate CA car as of 072301. Had it tuned up and checked out by reputable shop. Ran good when returned but mechanic thinks I have a linkage problem causing a very fast idle (2000+ rpm). I replaced bushings in pedal and bell crank underneath but to no avail. Car sometimes backfires periodically them it will go away. Thought it could be a bad distributor. I heard a Bosch 009 will work and is MUCH cheaper. Does anyone have any experience with this distributor. Also thought it could be a carburator problem. I have the original solex carbs. Have most of you changed to the webers and is this a big improvement.
I live outside the Baltimore, Maryland area. Any input would be greatly appreciated.
P.S. I took my first road trip 090601 to090901 to the vintage car races at Watkins Glen, NY. Great time. Anyone who has a chance should go to this event. What a GREAT CAR. Even though I didn't have the car long or know much about it, I figured what the hell. If it had to arrive in Baltimore on a truck a second time, so be it. But it made the trip and back.

WFBowen · WFBowen's Garage

I'd first check the cent. adv. on the distributor.As you probably know, if the rotor doesn't snap back when rotated, the advance mechanism is binding or the springs are bad. Massive amounts of WD40 shot all around under the breaker plate might loosen things up.
If possible, while it's running & idling high, go back to the engine and see if forcing the carb linkage closed (both sides at once) makes a difference. If so, it's just a matter of cleaning/oiling all the ball fittings, checking the return springs, etc. Hope this helps.

josh912 · 11-09-2001, 08:38 PM

Welcome to the 912 board! It seems like there are new people joining every other day. Anyway, let talk about you car. The 009 is a BAD distributor. Get the 050, if the distributor is the problem. Check the throttle linkages and make sure they are balanced on both sides (in sync) and check that they are returning to the idle stops on the carburators. Then check the timing. It should be about 3 degrees BTDC at idle. If that doesn't solve the problem, reduce the idle with the idle speed adjustment screws on the carburetors. Also check the plugs and wires. They can give you big headaches. Check the valves and see that they are adjusted properly. Coils are known to cause problems, but I don't think a high idle would be a result of a malfunctioning coil. Good luck and congrats on your new 912!

mark 69 912 · 11-09-2001, 10:41 PM

I had the same problem with the idle running very high. If I put the clutch in and acted like I was starting off I could get the idle down. I have the origional distributor and solexs. The mechanic found a plate warped in the solexs causing the idle to stay high. Now it runs perfectly, no back fires and great idle. Wish I could remember the name of the part replaced but much cheaper than replacing everything else. Good luck.

pokemon · 11-10-2001, 12:41 AM

1. Solexes worn their throttle shafts eventually. Then air can leak past them and cause a high idle. This is costly to repair.
2. pull of both arms to the carbs. Then the carbs must go to their end stops. If not, check the return springs.
3. remove the return springs and rotate the throttle shafts by hand. They must run smooth.
4. For the distributor, go for the 050. First try to put a few drops of light oil on the advance mechanism and see if that helps.

Good luck,

klmsouth · 11-12-2001, 11:05 AM

Would you happen to be running K&N's on those solexes. Forgive me if I sound like the begginer that I am but, I have the K&N's on my solex's and I had a terrible high idle from the 912 that I bought in july. Could not figure it out. To my surprise I pulled four screws out of the carbs that had fallen in over time. They were the screws that were supposed to hold the K&N's on. Immediatley fixed my idle problem. Just a long shot But those with K&N's watch those screws. I just used a magnet to retreive them.

pokemon · 11-12-2001, 10:27 PM

You have been very lucky these screws didn't enter the engine!
Now about K&N filters. An enginetuner I spoke some time ago about these filters is not too happy about them. He finds crud in ALL carbs fitted with K&Ns! He only approves them if you use the extra cover you can pull over them. Then they are OK.
A bad filter will wear out an engine very quickly.
Personally I find K&Ns too expensive and used paper filters on my Dellorto's instead. I replace them once a year.

klmsouth · 11-13-2001, 07:20 AM

Thanks for the info on the K&N's. These filters were on the car when I got it. I am at this time just rying to keep it running, but I will consider different filters.