rough idle with SPICA

2024 Views 3 Replies 2 Participants Last post by Andrew, Oct 2, 2007

Rumi Faizer

Discussion Starter · Oct 2, 2007

I have recently replaced my thermostatic actuator on a 1969 spider. THe car was set up to run essentially with a non-functioning actuator. Once I put the working unit in I adjusted it to give a near non-existent gap when hot. WHen cold there is quite a large gap. With the long rod adjusted appropirately (when the engine is hot it slightly widens the gap (0.40 mm), and the short rod to just close the air intake, the car ran with a warm idle that was smooth, but around 1100 rpm. I decided to back of on the fuel mixture screw (there is no solenoid on the '69 SPICA). This lead to a lower idle speed, but the idle is definitely rough, with intermittent sputtering. What should I do? Should I be adjusting the air intake somehow? On this car the usual valve to adjust air intake that is on newer SPICA cars is not present. I have no idea how to lower the idle air mixture. Could this be a spark plug issue (the car had clearly been running rich until I got the new actuator in). Could this be a timing issue?

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Andrew

· #2 · Oct 2, 2007

The 69 cars have four "dashpots" on the side of the airbox, one per cylinder, to adjust the idle air.

Can you get the gap adjusted to .019" hot with the long rod removed? How is the TA extension hot and cold?

Have you checked the distributor to make sure your ignition timing is dialed in first?

Andrew

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Rumi Faizer

Discussion Starter · #3 · Oct 2, 2007

Andrew said:
The 69 cars have four "dashpots" on the side of the airbox, one per cylinder, to adjust the idle air.

Can you get the gap adjusted to .019" hot with the long rod removed? How is the TA extension hot and cold?

Have you checked the distributor to make sure your ignition timing is dialed in first?

Andrew

Found the "dashpots". Turning the valves counterclockwise looks like it's supposed to close the space between the covers for these "dashpots" and thereby limit air in. The covers inside material is messed up, so I can't really get a flush fit. Ended up covering all valves with 3M double sided tape (it fills the gap between the cover and the valves perfectly). The car now idles at 750 rpm really smooth when hot and still revs and runs strong on the road. I'll see if this affects cold start on my way home today! I'm hoping, other than the "unprofessional" element to this fix, that it's not bad for the car. Let me know. I suppose this is what people hate about former owners when they discover things about their recently bought alfa...

Thanks

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Andrew

· #4 · Oct 2, 2007

Well if you've covered the four dashpots completely, then the engine is getting its idle air from somewhere else, probably past the throttle butterflies. At idle, the butterflies are supposed to be fully closed, and all the air is supposed to be coming through the idle circuit.

On the other hand, if it now ain't broke, don't fix it.

Andrew

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