Itinerant Air-Cooled

Randy in Maine wrote:Here is a photo on adjusting the idle speed (this is in a FI beetle though)....

Amakeptic wrote: "this spring"

Is the small amount of adjustment from sliding the screw up or down all that is available?

Tim soldiering on

Yes, but it's a controlled vacuum leak to adjust the cold idle speed. Wide open it's about 2000rpms

Bleyseng wrote:Yes, but it's a controlled vacuum leak to adjust the cold idle speed. Wide open it's about 2000rpms

Because it is all already-metered air, let's call it a bypass around the throttle plate. I have only ever gotten a 1,300 rpm idle with an open AAR.
Colin

Busboytom and I found about 2,000 RPM with his engine on over-adjusted accident. I think a lot of it has to do with drag on the transaxle and engine side, perhaps due to his engine being 19 years old…… BB, my '76 could get about 1,800 if I really cranked the opening. But I kept it around 1,400 to not wake the neighbors…

asiab3 wrote:Busboytom and I found about 2,000 RPM with his engine on over-adjusted accident. I think a lot of it has to do with drag on the transaxle and engine side, perhaps due to his engine being 19 years old…… BB, my '76 could get about 1,800 if I really cranked the opening. But I kept it around 1,400 to not wake the neighbors…

Perhaps with an already warmed-up engine . . . . ?
Was the engine overnight cold? I have never experienced an open AAR on a warm engine. The BobD and Naranja in their few winter morning starts, never got above 1,300.
Colin

Busboytom was having a cold start issue where the engine would fire a few excruciatingly slow rotations and die. The AAR was not open at all. We cranked it open and got about 2,000 RPM once the bus started. (Interestingly enough, it still had the issue. Two false starts, followed by a smooth idle at whatever we had the AAR set to, so we took it back down to something respectable.)

If you want MORE than 1,300 RPM, just warm the AAR up in the car for a few minutes to "preload" the heating element against your adjusting tool of choice. Then adjust the AAR as normal, so when the spring retracts as the element cools, it opens the aperture more than we can get with long skinny implements. Its a handy trick for "performance cam" installations, as the AAR can still close all the way even when hyper-adjusted.

Robbie

asiab3 wrote:Busboytom was having a cold start issue where the engine would fire a few excruciatingly slow rotations and die. The AAR was not open at all. We cranked it open and got about 2,000 RPM once the bus started. (Interestingly enough, it still had the issue. Two false starts, followed by a smooth idle at whatever we had the AAR set to, so we took it back down to something respectable.)

If you want MORE than 1,300 RPM, just warm the AAR up in the car for a few minutes to "preload" the heating element against your adjusting tool of choice. Then adjust the AAR as normal, so when the spring retracts as the element cools, it opens the aperture more than we can get with long skinny implements. Its a handy trick for "performance cam" installations, as the AAR can still close all the way even when hyper-adjusted.

Robbie

Would you look at THIS? I just learned something useful. Never even thought of that splendid little trick.
I am so washed up by you sharp youngsters.
Colin

I think necessity was the mother of that invention. Have you ever NEEDED to get the BobD bus to shoot right on up to 2,000 rpm at cold start?

Robbie

asiab3 wrote:I think necessity was the mother of that invention. Have you ever NEEDED to get the BobD bus to shoot right on up to 2,000 rpm at cold start?

Robbie

Never! My L-Jet buses are the model of crisp reliable instant starts with perfect drive-off manners . . . like Chloe
NaranjaWesty is getting better and better now that it is not digesting continuous varnish, starts immediately, drives off with only a slight lean gulp if I hit it too hard. Today was only 87, CHTs 407 @ 65, 17.4 mpg, one truck pass to 75 mph, engine asked for more.
ColinInTemecula
(Jim at Interstate says hello)

Did I tell you Buddy balked at me ONCE this year? Floored it for safety, fresh out of a "Pure Gas" station in Jackson Hole and I got a locked-up seatbelt for a few seconds before it sprang back to life. I'll stick to the ethanol stuff, I guess.

I wish our carbureted rigs had the adjustability of the AAR for cold idle. Really Cold Mornings don't have the verve of a mild summer day's cold start… I want the speed but I don't need the enrichment of "more choke." But now we're splitting hairs…

Robbie
(Jim better not sell the business while I'm gone)

asiab3 wrote:Did I tell you Buddy balked at me ONCE this year? Floored it for safety, fresh out of a "Pure Gas" station in Jackson Hole and I got a locked-up seatbelt for a few seconds before it sprang back to life. I'll stick to the ethanol stuff, I guess.

I wish our carbureted rigs had the adjustability of the AAR for cold idle. Really Cold Mornings don't have the verve of a mild summer day's cold start… I want the speed but I don't need the enrichment of "more choke." But now we're splitting hairs…

Robbie
(Jim better not sell the business while I'm gone)

He's hanging on to it with a move in the works.

Chokes are adjustable both for interval and rpm. You don't HAVE to follow the directions. In the summer, Chloe's fast idle screw is about a half turn off the fast idle cam. In the fall and spring, that sucker is a good 1/2 turn out and I steal a little big brass screw air flow. Remember that the VWs with the vacuum retard also had a massive 12* timing advance any time the chokes had the throttle plates tipped. They were calibrated with correct distributors functioning correctly . . .
Colin

asiab3 wrote:just warm the AAR up in the car for a few minutes to "preload" the heating element against your adjusting tool of choice. Then adjust the AAR as normal, so when the spring retracts as the element cools, it opens the aperture more than we can get with long skinny implements.

Hey Robbie, I'm hoping you can clarify this a little more for me. I'm not sure where I'm going wrong. I tried putting a screwdriver in through the gateway opening up the aperture and then held a heat gun to the unit to preload that bi-metal piece. I then loosened the 7mm screw and retightened. The first Time I tried it the screw was already in the up position (bigger aperture). The second time I tried it with the screw starting in the lower position (smaller aperture) and then after the heat was applied I loosened the adjusting screw and slid it up to the top position and tightened it. The third time I tried it I loosened the adjusting screw, applied the heat and then tightened the adjusting screw. All three attempts were with the screw driver inserted holding the aperture open. I didn't achieve any results that were different than simply adjusting the screw as normal. Any ideas of what I may be missing?

I found this picture over on an Alfa Romeo Site and not sure if they work exactly the same, i.e. the spring at 2 is what closes the aperture and the bi-metal strip at 1 is moved to the right with more heat and left with less heat. It seems the adjustment screw adjusts the entire plate represented by 4,5 and 7 which I affirmed by watching the oval move slightly on mine as I adjusted the screw up and down. Do you know how the adjustment affects the aperture plate? Is it just a stop of some kind? I originally thought that the piece to the right of 4 was a stop, but on closer examination it appears to be a ribbed part of the 4,5 and 7 Plate and sits completely behind the aperture plate.

Hoping to get some dissection of this and learn what I can here

Tim

I'm not sure your heat gun "trick" is going to work here; I've never tried it. I physically ran the can until the AAR allowed the idle to return to sub-1000 RPM when I pulled Tom's AAR and performed the adjustment as follows:

Ensure (by sight) that the AAR is closed (from running the car, or 12v applied for five minutes on the workbench)
Operate the flap with small screwdriver to check for binding
Open the flap as far as you can
Loosen the 6mm nut
Tighten the 6mm nut

I'm not sure if that is even the correct procedure, but it has worked for me on two separate occasions. That's enough for me to consider it "almost scientifically validated."

Robbie

MountainPrana wrote:
Hoping to get some dissection of this and learn what I can here

Tim

As per the Alfa photo, could you bend #1 to arc the disc more open. Problem is partially solved just by breaking the orientation of the parts to access the internals. You would have to index the parts at disassembly, and you might have a chance to optimize the opening just by the location of the nipples as you orient things at reassembly.
Colin