1959 Fuel Injection Idle speed

[Jerry C.]

What should be the fast idle speed at startup? I know it will increase after startup but just when you first start it and as it comes off fast idle what is the warm idle speed? Thanks in advance.

[Jim L.]

Re: 1959 Fuel Injection Idle speed

My '60 starts around 1100 RPM. As the engine warms, and if I don't tap the accelerator pedal, it will increase to around 1500 RPM.

Note, though, that I've disabled the actual cold enrichment that makes the ratio lever stay on the power stop. All that's going on with my FI is fast idle. I've done this to get rid of the annoying rich condition that invariably happens when the cold enrichment is on.

Jim

[John D.]

Re: 1959 Fuel Injection Idle speed

Jerry, Fast idle should be 1800 RPM. Now this depends on the temperature outside and if the sun is hitting the hood of a 57 to 61 and maybe a 62 also.
On page 1 of the JM it says, "FI cars will increase in RPM slights as idle enrichment valve in choke housing switches to normal rung". Rung is a typo?
Anyhow normal idle should be in the 800 RPM range for HHP. Low HP should be in the 500-550 range. It would be helpful if the manuals spelled this out. Check the owners manual and see what it says as I don't have yours. My numbers came from Rochester Products& also the Corvette Servicing guide. See page 6-3. I quickly spotted that a 58-59 290HP should idle at 800. I personally like my fuel cars to idle a tad higher but for PV you better listen to the general.
Ask Tim Mickey what idle speed he likes to see. Let us know his answer Jerry. Thanks, John

[John D.]

Re: 1959 Fuel Injection Idle speed

Hi Jim, The condition of the bi-metallic spring in the "choke can" has a lot to do with your problem. Repros of the choke can assembly are tough to come by at this time but look for them in the near future.
Another thing I do is completely disasemble the choke housing on the 57 to 61`s. I remove all the lead shot, welsh or welch plugs and clean out all the carbon and crap. This helps the primitive cold enrichment work a lot better although it's very time consuming.
Then came the 62 with a bubba choke assembly but it does work a lot better than the 61 down. John

[Tom P.]

Re: 1959 Fuel Injection Idle speed

Hi Jim, The condition of the bi-metallic spring in the "choke can" has a lot to do with your problem. Repros of the choke can assembly are tough to come by at this time but look for them in the near future.
Another thing I do is completely disasemble the choke housing on the 57 to 61`s. I remove all the lead shot, welsh or welch plugs and clean out all the carbon and crap. This helps the primitive cold enrichment work a lot better although it's very time consuming.
Then came the 62 with a bubba choke assembly but it does work a lot better than the 61 down. John

"--------------62 with a bubba choke"???????????????????
OK John, I don't get that one???? The 62 choke on the 7011956 unit on my 56 works "as advertised"!

[Jim L.]

Re: 1959 Fuel Injection Idle speed

"--------------62 with a bubba choke"???????????????????
OK John, I don't get that one???? The 62 choke on the 7011956 unit on my 56 works "as advertised"!

Ah, yes, but Tom, back in '62 there was no requirement for truth in advertising.

Jim

[Michael H.]

Re: 1959 Fuel Injection Idle speed

Jerry, Fast idle should be 1800 RPM.

I think there's more to the story on "fast idle speed". There's no such thing as a "correct cold engine fast idle speed" spec.

[Jim L.]

Re: 1959 Fuel Injection Idle speed

Hi Jim, The condition of the bi-metallic spring in the "choke can" has a lot to do with your problem.

Hi John,

Dunno if this is a problem or not. The engine in my '60 simply needs no cold enrichment at all down to a starting ambient of 40 degrees. (Any colder than that, I'm staying inside by the woodstove.) Fast idle is adequate to keep the engine running and it turns off after a couple of minutes.

Repros of the choke can assembly are tough to come by at this time but look for them in the near future.

Now that's good news!


Jim

[John D.]

Re: 1959 Fuel Injection Idle speed

Fast idle speeds are typically in the range of 1500 to 1800 depending on many variable factors. I talked to a team leader today and he said he doesn't look at the tach at all doing PV. He just listens to the sound of the engine to see if it has a decent fast idle. Then he uses the same approach on the regular idle. But the manuals call out for a certain fixed fast idle. My 63 fast idle when the engine is ice cold is set at about 1800-1900. Then when it heats up it's 850-900 plus.

[Michael H.]

Re: 1959 Fuel Injection Idle speed

But the manuals call out for a certain fixed fast idle.

My 63 fast idle when the engine is ice cold is set at about 1800-1900. Then when it heats up it's 850-900 plus.

I have to wonder where that spec/RPM came from because, again, there is no such specification published in any GM manual.

If your 63 runs at 1800-1900 when ice cold, I think it's set wrong.