[TPR] More follow up from Chuck Nyutten

Tue Jan 7 12:45:32 PST 2014

yeah, spending an extra 10 bucks on knock insurance is silly. :)  I typically run some race gas because it gives me a warm fuzzy feeling.

JB

________________________________
 From: Steven Donegan <steve at donegan.org>
To: John Bentley <gndplne at yahoo.com>; Mad Dog Antenucci <teampantera at yahoo.com>; Asa Jay Laughton <asajay at asajay.com>; "tpr at teampanteraracing.com" <tpr at teampanteraracing.com> 
Sent: Tuesday, January 7, 2014 12:30 PM
Subject: Re: [TPR] More follow up from Chuck Nyutten

Agreed that rich is better than lean :-) So if you live at or near sea level tune to the hilt for there and you should be good to go at Ely. BTW - at higher altitudes cylinder pressures on a NA engine drop - so buying nasty expensive race gas in Ely may not be worth it :-)

____________
Steven Donegan
SSCC/NORC Life Member, Car #86
www.sscc.us

________________________________
 From: John Bentley <gndplne at yahoo.com>
To: Steven Donegan <steve at donegan.org>; Mad Dog Antenucci <teampantera at yahoo.com>; Asa Jay Laughton <asajay at asajay.com>; "tpr at teampanteraracing.com" <tpr at teampanteraracing.com> 
Sent: Tuesday, January 7, 2014 12:15 PM
Subject: Re: [TPR] More follow up from Chuck Nyutten

agreed, pyrometer also a good thing, however, a normally-aspirated v-8 at 5500 rpm is a totally different animal from a horizontally opposed force-fed aluminum flat 6 at 2400 RPM.  Where to run the mixture in an aircraft engine is another loooong topic.  50 ROP or 50 LOP?  Ask 10 people and you'll get 11 answers.  I always run the turbo-charged 520 cubic inch engine in my plane ROP and depending on other considerations, maybe even 100 ROP.  I let EGT and CHT guide my decision.

Since both Asa and I live closer to sea-level and race at 6 or 7,000 feet, I still say get it dialed in for proper mixture for lower altitude and then when you get to Ely and run 5 or 6,000 RPM, you will have a rich mixture and that is a good thing.  Lean at high RPM=real bad.  I'm sure very few people run a knock sensor on a Cleveland and detonation at lean mixtures at high rpm is difficult to hear.  My 2 cents is to run rich for endurance racing at high RPM and run a higher octane fuel than normal.  If you have the time and money to dyno at Ely as well and then change jets and power valve in Ely that's a good thing.  In the 13 years I've been running in Ely, this method has worked well for me.

Your Mileage May Vary, this is not legal advise, some assembly required, batteries not included.

JB

________________________________
 From: Steven Donegan <steve at donegan.org>
To: John Bentley <gndplne at yahoo.com>; Mad Dog Antenucci <teampantera at yahoo.com>; Asa Jay Laughton <asajay at asajay.com>; "tpr at teampanteraracing.com" <tpr at teampanteraracing.com> 
Sent: Tuesday, January 7, 2014 9:33 AM
Subject: Re: [TPR] More follow up from Chuck Nyutten

I suggest, besides the oxy sensor bung, you also do a run with a pyrometer in that same bung - in small turbo airplanes the usual thing is to lean out the mixture until you hit peak temperature then back it off a bit - the same applies to automotive engines :-)

Given a carb, and altitude differences, if you are perfect at sea level you likely will be rich at Ely - it might be cool to actually see how much difference there is and/or re-tune at Ely and again at R Place for the run back to Vegas...

____________
Steven Donegan
SSCC/NORC Life Member, Car #86
www.sscc.us

________________________________
 From: John Bentley <gndplne at yahoo.com>
To: Mad Dog Antenucci <teampantera at yahoo.com>; Asa Jay Laughton <asajay at asajay.com>; "tpr at teampanteraracing.com" <tpr at teampanteraracing.com> 
Sent: Tuesday, January 7, 2014 9:18 AM
Subject: Re: [TPR] More follow up from Chuck Nyutten

My carb is a Holley 0-4778.  I have changed the jets based on dyno runs with an oxygen sensor.  The carb as-built runs very rich. I also changed the power valve based on engine vacuum.  I would caution you on making any seat-of-the-pants mixture adjustments.  Just have a bung put in at least one of your headers and measure it.  A little rich is always better than a little lean, especially at high rpm.

I have had it above 150 MPH many times but always ran out of balls before running out of
 carb. :)  My car desperately needs a front air dam since above 150 it gets very light in the front.  I have the air dam, just never got around to putting it on.

The 0-4778 is a 700 CFM double-pumper.  Works well around town and also at Silver
 State. 
 Its on a Blue Thunder low-profile dual plane manifold on 4V closed-chamber iron heads.

I agree with Chuck, I would not put a vacuum-secondary carb on my Pantera.

Grumpy

________________________________
 From: Mad Dog Antenucci <teampantera at yahoo.com>
To: Asa Jay Laughton <asajay at asajay.com>; "tpr at teampanteraracing.com" <tpr at teampanteraracing.com> 
Sent: Tuesday, January 7, 2014 7:31 AM
Subject: Re: [TPR] More follow up from Chuck Nyutten

Bud can do 130?
At Silver State? ;-)

Look I can do 185 at sealevel and Bud is somewhere south of sealevel! HAHA
Here's the guys to ask....what is JB running for a carburation...he has had several runs between 130-135 AVERAGE which meant he was hitting 150-160 in straights....

Note to Grumpy:  Chime in here with your wisdom ;-)

On Monday, January 6, 2014 10:05 PM, Asa Jay Laughton <asajay at asajay.com> wrote:

Hi gang,

As I continue my edumacation bout cars and stuff.... I wrote Chuck
    again asking about the option of a vacuum secondary carb instead of
    a double-pumper as he originally recommended.  He was candid in his
    response and I take it with the same grain of salt I try most things
    with.  You can read the trail below.

I also talked with our friend Bud Hower, who sent photos and specs
    of his carb.  His Holley is nearly identical to mine, though it may
    not be an "emissions" model, and he gets 130 top end without a
    problem and maybe more.  That may simply mean mine being an
    emissions carb might be channeled and jet differently... for fuel
    economy and not top end.

Note, I'm not spending any more yet, I'm still investigating.
Asa Jay

-------- Original Message -------- 
Date: Mon, 6 Jan 2014 14:45:10 -0600 
From: <form at chucknuytten.com> 
To: 'Asa Jay Laughton' <asajay at asajay.com> 

If you are going to buy a new carburetor, I would not recommend a vacuum secondary carburetor. I use double pumper carburetors on many vehicles that claim they use them on performance street vehicles. I stay with my original recommendation of a 750-2003 carburetor $833.00. 
Vacuum carburetors tend to drop back on performance on the top end and that is exactly the condition you are describing. A vacuum carburetor is a good choice if you only want fuel economy but you are not going to be happy with that carburetor when you want to go racing. 

From:Asa Jay Laughton [mailto:asajay at asajay.com] 
Sent: Friday, December 27, 2013 1:33 PM
To: form at chucknuytten.com
Subject: Re: Friend or Fellow Racer

Thank you for the recommendation.  Based on the fact I don't race the car all the time and in fact drive it more as an around-town car until open road race season, I would think a vacuum secondary would be better for fuel economy.  Presently I get nearly 22 MPG on the highway, which is nice; when racing, it doesn't really matter as long as enough fuel is being metered to the engine.  However, during the SSCC this year I felt the carb was leaning out and perhaps even starving the engine at high rpm, which is why I'm investigating a new carb.

Do you work with vacuum secondary carbs and what is your opinion
        of them?
Thank you,
Asa Jay

Asa Jay Laughton, MSgt, USAFR, Retired
& Shelley Marie
Spokane, WA
******************************     
http://www.racingagainstautism.com
http://www.teampanteraracing.com
http://facebook.com/racingagainstautism

On 12/9/2013 8:51 AM, form at chucknuytten.com wrote: 
If you want performance, I have a  750-2003 double pump carburetor, four corner idle which would work very well for your situation. $833.00 I looked up the carburetor you presently are running and according to the Holley info I would not recommend putting any more money into that core.  Your present carburetor is an ok core for general use but not the best core for performance.

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