[DeTomaso] DeTomaso Digest, Vol 86, Issue 21 Critical Rpm

Sat Sep 24 09:31:18 EDT 2011

Hi John

It's true that the idle circuit still provides power at a higher speed, it
doesn't close off, so it provides power all the way to WOT Top speed. But:
1. Its effect becomes relatively less and less as the primary jets, power
valve and secondary jets come in. 2. You have to adjust the idle speed to
give good drivability in the low mph area, so you can't use it to adjust a
problem at higher speeds, there you have to play with jets etc.

Idle speed jets do influence idle speed circuit. I just never had an
engine/carb where it was necessary to change them, I've been fortunate
enough to be able to fix any low speed problem by turning idle speed screws
only. And as it says on the main page on tuningmadeeasy.com, we only discuss
things that we've tried ourselves.

Mikael

Fra: John Taphorn [mailto:jtaphorn at kingwoodcable.com] 
Sendt: 24. september 2011 14:24
Til: Mikael; RCBSONS1 at aol.com; oldwheel at shaw.ca; detomaso at realbig.com
Emne: Re: [DeTomaso] DeTomaso Digest, Vol 86, Issue 21 Critical Rpm

Thanks Mikael, The article makes my point as it states:

"Your idle circuit controls how your engine behaves 90% of the time. Because
the idle circuit provides power up to around 60 mph/100 km/t."

I discovered that my idle circuit is engaged while cruising at speeds to
over 80MPH.  This is the case with most of us.  It applies to you if while
traveling at high speeds down the highway, you barely have the gas pedal
depressed.  

However, the article only addresses adjusting the idle speed screw and not
the more important sow idle speed air jets.  I assume that is because most
Holleys do not have removable low speed air jets and therefore it is
difficult to adjust that parameter.  However, most higher end aftermarket
Holley based carbs do have screw in removable jets that look kike main jets,
only smaller.  These are simple to change by only removing the air cleaner.

JT

----- Original Message ----- 

From: "Mikael" < <mailto:mikael_hass at mail.tele.dk> mikael_hass at mail.tele.dk>

To: "'John Taphorn'" < <mailto:jtaphorn at kingwoodcable.com>
jtaphorn at kingwoodcable.com>; < <mailto:RCBSONS1 at aol.com> RCBSONS1 at aol.com>;
< <mailto:oldwheel at shaw.ca> oldwheel at shaw.ca>; <
<mailto:detomaso at realbig.com> detomaso at realbig.com>

Sent: Saturday, September 24, 2011 12:46 AM

Subject: SV: [DeTomaso] DeTomaso Digest, Vol 86, Issue 21 Critical Rpm

> Allow me to suggest doing a full tune up of the carb, 90% of the time that
> fixes things faster than us helping via email...
> 
> If you like, follow process on my website, and feel free to contact me if
> anything is unclear, or if the problem doesn't go away
> 
>  <http://www.tuningmadeeasy.com/tuning/tuning-a-carburetor-part-1/>
http://www.tuningmadeeasy.com/tuning/tuning-a-carburetor-part-1/
> 
>  <http://www.tuningmadeeasy.com/tuning/tuning-a-carburetor-part-2/>
http://www.tuningmadeeasy.com/tuning/tuning-a-carburetor-part-2/
> 
> A Pantera that is not properly tuned is a Pantera wasted. I should be in
> marketing. Or maybe not :-)
> 
> Mikael
> 
> -----Oprindelig meddelelse-----
> Fra: John Taphorn [mailto:jtaphorn at kingwoodcable.com] 
> Sendt: 23. september 2011 00:59
> Til:  <mailto:RCBSONS1 at aol.com> RCBSONS1 at aol.com;
<mailto:oldwheel at shaw.ca> oldwheel at shaw.ca;  <mailto:detomaso at realbig.com>
detomaso at realbig.com
> Emne: Re: [DeTomaso] DeTomaso Digest, Vol 86, Issue 21 Critical Rpm
> 
> Bob
> 
> In my previous post I mistaken stated low idle speed screws when I meant
> "jets".  On your big carb the main jets probably are not part of the
> equation until over 3000RPM.  Smaller slow speed idle air jets will richen
> the mixture before the main jets are engaged.
> 
> I believe my car acted as you described.  This was the fix.
> 
> JT
> ----- Original Message -----
> From: < <mailto:RCBSONS1 at aol.com> RCBSONS1 at aol.com>
> To: < <mailto:oldwheel at shaw.ca> oldwheel at shaw.ca>; <
<mailto:detomaso at realbig.com> detomaso at realbig.com>
> Sent: Thursday, September 22, 2011 5:20 PM
> Subject: Re: [DeTomaso] DeTomaso Digest, Vol 86, Issue 21 Critical Rpm
> 
> 
>> In reality it only does it when lugging the motor
>> but you cannot run in that spot very long
>>
>> I have jetted my car up several times before
>> going to the track to keep it from running lean
>> which it still shows slightly at full tilt... even
>> though I am going up in elevation
>>
>> I though about doing a dyno run but decided
>> it made no sense as the car runs good enough
>> and it seems like most of the tracks I run
>> are at elevation so it would have to change again
>>
>> I could back the jets down a little in my
>> area to get a little more snap but it is actually
>> easier to drive with it a little rich.. not as edgy
>>
>> Bob Benson
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> 
> 
> 
>

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