Idle RPM's

David, it's been so quiet and peaceful around here lately. Everyone's been getting along. No disagreements. No heated exchanges.

But now, this.

This should be interesting...

The question depends on a lot of things. The setup determines a lot, cam choice in particular. Generally, people will tell you to tach it down as slow as possible, as long as it will still stay running. Something else to keep in mind is that we have no chokes, so if you set the idle for 800 when it's hot, it'll never idle at all until you've driven it for 15 minutes (unless you are pig-rich). Running closer to stoich, cold idle is pretty iffy unless hot idle is set higher than anybody would like.

A W120 or the like will idle down to 750 RPM. Something bigger will want/need more. I like about 1000 RPM with my FK8, but other guys set them a bit higher.

Your mileage may vary.

Basically, I do what Stan said.

I set my idle as low as I can, so that it will just idle from a cold start without me having to feed any gas - in the coldest weather I ever drive the Speedster in, which is about 45 degrees.

It sputters and coughs for about 30 seconds before settling down to about 700 rpm. Of course, by the time it's warm, that's risen to about 1100, but I don't care. It's not hurting anything to do that, and maybe helping the engine stay a little cooler when I'm stuck idling at a light for three minutes in really hot weather.

My engine is a 2024 - a 2110 with a slightly shorter stroke (78.8 mm vs 82 mm) and an Engle W120 cam.

By the way, any idea what the knob in this photo of a real Speedster is? Hint: It's NOT the wiper switch.

That's right, it's the hand throttle.

So, why did 356's need a hand throttle? Was it an early form of cruise control?

Well, no.

It was to keep the engine from stalling when starting from cold. From the 'A' models on (I think), there were no chokes, just like on most of our twin carb cars. If we had hand throttles, we could set our idles lower, too.

But we don't, so we can't.

I have thought about using the unused lever beside the handbrake for a hand throttle or choke.

I did not realize my question would ignite controversy. Thx for input.

cut the crap: 900.  Next??

Bottom line.. anything above stall and as long as you have decent oil pressure and  a smooth  idle that's where you want to set it.  Unless you ride a Harley then it is Law that you must have the idle 10 Rpm's above ultimate stall .

That’s for sure. I think the average Harley guy wants to hear each individual cylinder firing.

"For those who know, no explanation is necessary, for those who don't, no explanation is possible."

So cold idling at 3k on a 90° temp day is normal? I doubt it. It did kick down to 1800 RPM's after it (the engine) warmed up. 

DAVID BAYNE - BAYNIAC posted:

So cold idling at 3k on a 90° temp day is normal? I doubt it. It did kick down to 1800 RPM's after it (the engine) warmed up. 

I don't think anybody said that.

Well....no.

Are you saying you can't get the idle below 1800 with the idle screws backed out all the way? And that the idle starts out at 3000 from cold?

Something's definitely amiss.

What kind of carbs? What type of linkage? How long have you had the car? Did this behavior just start?

Sacto Mitch posted:

 

Basically, I do what Stan said.

I set my idle as low as I can, so that it will just idle from a cold start without me having to feed any gas - in the coldest weather I ever drive the Speedster in, which is about 45 degrees.

It sputters and coughs for about 30 seconds before settling down to about 700 rpm. Of course, by the time it's warm, that's risen to about 1100, but I don't care. It's not hurting anything to do that, and maybe helping the engine stay a little cooler when I'm stuck idling at a light for three minutes in really hot weather.

My engine is a 2024 - a 2110 with a slightly shorter stroke (78.8 mm vs 82 mm) and an Engle W120 cam.

By the way, any idea what the knob in this photo of a real Speedster is? Hint: It's NOT the wiper switch.

That's right, it's the hand throttle.

So, why did 356's need a hand throttle? Was it an early form of cruise control?

Well, no.

It was to keep the engine from stalling when starting from cold. From the 'A' models on (I think), there were no chokes, just like on most of our twin carb cars. If we had hand throttles, we could set our idles lower, too.

But we don't, so we can't.

 

Mitch:

Did you know you have a hand throttle for cold starts?

heres how to find it:

1.  stand up

2. look straight down

3.  You will see two feet

4. Locate right foot

5. Now when you start your car from a cold start,  Apply slight downward pressure to the gas peddle using the right foot you located earlier.

6. Using this method we will call, “foot throttle control for cold starts”,  apply enough downward pressure, again using the right foot you located earlier, on the the gas peddle to run the engine between 1500 and 2000 rpm. No more!   Try to keep a contestant pressure for 2 to 3 minutes then let the car idle itself until warm.

Hope this works for you guys 

just trying to help ya know

tebs

@Tebs  Now you did it, unlocked the secret to a cold idle :~(

Sacto Mitch posted:

 

Basically, I do what Stan said.

I set my idle as low as I can, so that it will just idle from a cold start without me having to feed any gas - in the coldest weather I ever drive the Speedster in, which is about 45 degrees.

It sputters and coughs for about 30 seconds before settling down to about 700 rpm. Of course, by the time it's warm, that's risen to about 1100, but I don't care. It's not hurting anything to do that, and maybe helping the engine stay a little cooler when I'm stuck idling at a light for three minutes in really hot weather.

My engine is a 2024 - a 2110 with a slightly shorter stroke (78.8 mm vs 82 mm) and an Engle W120 cam.

By the way, any idea what the knob in this photo of a real Speedster is? Hint: It's NOT the wiper switch.

That's right, it's the hand throttle.

So, why did 356's need a hand throttle? Was it an early form of cruise control?

Well, no.

It was to keep the engine from stalling when starting from cold. From the 'A' models on (I think), there were no chokes, just like on most of our twin carb cars. If we had hand throttles, we could set our idles lower, too.

But we don't, so we can't.

 

Sure you could .... 

Alan

Yes I felt is was time the secret be revealed ..   After reading each and every super mega selling guide book written by Terry Nuckles, pen name “Terry Knuckles” 

I feel I must impart some of my wisdom obtained from those invaluable books

its just best for all In The SOC.. 

best regards

tebs

Teby S posted:

 

...Try to keep a contestant pressure for 2 to 3 minutes then let the car idle itself until warm.

 Thanks for the tips, Tebs.

Problem is, I'm not a good contestant. I want the car to warm up on its own without a struggle. I have trouble concentrating on anything for more than two minutes at a time.

I want to just turn the key, get back to my texting, and let the car take care of itself.

Do I need to phrase this in the form of a question?

Stan Galat (see above) has prompted a question: How much

is "pig rich?"

Oink!

"Pig rich" is anything richer than 12:1, gasoline washing the oil off your cylinders and scoring the crap out of them!

I had a hand throttle which works VERY well for east coast cold fall and spring morning warmup. Yes, I used to drive top-down in 32 F weather. Yes, I'm stupid, but not dumb. Although I guess that point is debatable considering what I just typed......

Anyway, sans hand throttle, 900 or so warm translates to about 500 or 600 cold. Works for me.

Now you have me worried that I may have scored my cylinders.

Sorry.....

lIving at 6500 ft qualifies as Pig Rich. Tony has my car set up so that it actually runs quite well at this altitude. Starts easily, idles perfectly, and never sputters unless it is really cold and been sitting for a long time. However I get about 12 mpg and a lot of soot on the bumper. A side benefit is it also runs well at sea level and gets considerably better gas mileage. 

Teby I have know about the secret idle control since I joined the Fraternity. I think the BOD may have to have a talk with you. What is next the secret handshake?

Per the Right Foot Technique so eloquently described above, I would add as a prologue the application of two or three rapid depressions of said foot to accel pedal before engaging the starter motor, followed by a few more during the starting procedure, as required.

As to wanting the car start with a turn of the key and take care of itself, you will have to go visit your local Honda or Porsche or _______ dealership, and drive out with one of their offerings.  The dawn of fuel injection and computer controlled everything has solved this problem for you.