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Discussion Starter · #1 ·
I did a search, but for some reason couldn't find it. I have a mid-70's 2L transplanted into my '69 spider.

Thanks for the help!!
Eric
 

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If SPICA, pull the big hose off the 'can of worms' between #2 and #3 that has a small hose going to each cylinder intake runner.
The large hose goes directly to the air filter housing. IOW, the thing right there that has 4 small and 1 large hose going to it.

The nipple where the hose goes onto that distribution block screws in and out and compresses/expands a rubber o-ring to alter idle speed. (well, if the o-ring isn't all dry rotted or stone hard anyway)

'Course if it IS SPICA you'll mabe wanna paruse the SPICA setup info too as an idle issue might not neccisarily be due to the idle setting if I understand some of the tricks the pump does correctly.

Carbs :shrug: could be a lot of places depending on type, brand, # of units.


EDIT:
Not a SPICA engine, but a SPICA idle air distribution block it be.
The nipple where the braided hose goes is what yer after.
 

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First of all I'll tell you what is NOT the idle speed adjustment. It's NOT the screw on the manifold that adjusts the throttle butterflies, like you would a carb engine. Both the idle and wide-open throttle stop screws are adjusted to precise angles using a factory tool. They should not be changed once set. On a Spica engine the throttle butterflies are closed completely at idle, and all idle air comes through the idle air distribution tower (the thing with the black tubes going to it) from the air box.

Inside the tower is a rubber o-ring that gets squeezed as you screw in the hose fitting that leads to the air box. Theoretically, that makes the air passage smaller or larger. The idle fuel delivery doesn't change, just the amount of air.

Now, that said, the idle adjustment on Spica is Rube-Golberg at best and does not modulate well. It seems regardless of the position of the o-ring that the engine will idle at 600-900 rpm if the system is tuned properly. That's the key. Make sure you go through the tuning process in lock step and verbatim.

If you have a high idle, it's likely that you have a failing Thermostatic Actuator (T/A), a mal-adjusted idle stop screw, or a mal-adjusted short rod. between the relay crank and the throttle butterflies. If this is the case, you need to do a soup-to-nuts tuneup. When tuning a Spica system each step depends upon the previous step being done correctly.

If you would like some Spica tech/tuneup material, PM me a email address.
 

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Semi-related question about the "can of worms" junction. SHould it "hiss" at all like it has an air leak. Not sure if it is a sucking air leak or an over pressure air leak but mine hisses. Is that right or does it need to be tightened, gasketed, or otherwise readjusted to stop that.

Thanks
 

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@Roadtrip: having read much of your and others' online writings, isn't the idle stop screw position critical only for setting the initial (baseline) relationship between the fuel pump long rod and throttle butterflies? After it is set with the "tool" or equivalent device, isn't changing its protrusion just akin to nudging the gas pedal or pulling the throttle lever? I.e., a tweaked idle screw should do no harm as the air fuel ratio will still be valid for the given throttle opening. With a larger than "baseline" protrusion, it may help nudge the idle speed higher to accommodate, say, use of an A/C compressor.
 

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Discussion Starter · #6 ·
Thanks for the info...

Also, my "can of worms" hisses quite loudly.
 

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Semi-related question about the "can of worms" junction. SHould it "hiss" at all like it has an air leak. Not sure if it is a sucking air leak or an over pressure air leak but mine hisses. Is that right or does it need to be tightened, gasketed, or otherwise readjusted to stop that.

Thanks
With all other adjustments properly set up it will make a hiss as you describe. Crank the adjuster in - the hiss will get louder and you will end up with a low, lumpy idle. Crank it out to wide open - the hiss goes away and you end up with a high, hunting idle. In the mid range you should have a smooth 650-700 rpm idle with some hissing which will not be heard when you connect the feed line from the air box to the idle air manifold.

The importance of the bellcrank stops, and especially the closed stop is that the throttle plates are slightly larger than the bores so you want them completely closed but not jamming in the bores and wearing them out every time you step on the gas. There's also a balance adjustment between forward and aft throttle bodies. When all is set up correct it works perfect.
 

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@Roadtrip: having read much of your and others' online writings, isn't the idle stop screw position critical only for setting the initial (baseline) relationship between the fuel pump long rod and throttle butterflies? After it is set with the "tool" or equivalent device, isn't changing its protrusion just akin to nudging the gas pedal or pulling the throttle lever? I.e., a tweaked idle screw should do no harm as the air fuel ratio will still be valid for the given throttle opening. With a larger than "baseline" protrusion, it may help nudge the idle speed higher to accommodate, say, use of an A/C compressor.
In essence, yes. But the stop screw must be at factory specs to get the "delta" correct between the short and long rods for tuning purposes. For an AC compressor load, I suppose you could install a high-idle solenoid like some carb'd cars had back in the 70s.
 

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This is a timely question for me. I have a '79 with its original SPICA, and it seems to me it's been idling a bit low lately. The car gets driven quite frequently, so its hard to tell for sure -- the frog in the water thing.

My SPICA hasn't been monkeyed with, and the car drives fine, so is this an indication that I now need a SPICA tuning?
 

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What do you call "low?" 600-900 rpm is the spec.

You might check the timing. Also, check the plug color for mixture.
 

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What do you call "low?" 600-900 rpm is the spec.

You might check the timing. Also, check the plug color for mixture.
Well, I guess it's mainly that it feels lower than it used to be. I get some vibration when I sit at idle, which I didn't used to.

My memory is suspect as to what the actual idle speed used to be, but if I slowly give it some throttle, the vibes disappear as it gets into the 600+ range.

Current idle is unknown, as it sits on the needle rest, but isn't that at the 500 mark?

Edit: Timing is probably a good place to look, as I'm still on points, and they haven't been adjusted or replaced in the last 3 years at least. Thanks for the tip.
 
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