[DeTomaso] FW: Moment of (sad) truth

Paul Timko thedrol at pobox.com
Tue Jul 1 15:36:22 EDT 2014


There is a line for air fuel mixture.  The scale is on the right side of 
the graph.  Each run has two lines, one for horsepower and one for A/F. 
  The A/F line is a lighter color version of the matching horsepower 
line.  So I'm guessing that the A/F for his engine is the one that has 
the 11.74 marked on it.

Paul
#9270

On 7/1/2014 2:16 PM, Pantdino via DeTomaso wrote:
>     i don't know how to read the graph for air/fuel mixture ratio, but is
>     that on there somewhere?
>
>
>
>     My basically stock motor had a 780 carb on it when I got it. I had to
>     switch to a 600 to pass smog way back when and the car was more
>     tractable after that with little change in max power so i never changed
>     back.
>
>
>
>     You are probably losing low and medium speed power due to insufficient
>     air velocity thru the venturis at those engine speeds.
>
>     When I put my other car on the dyno the guy could tell me the air/fuel
>     ratio at different speeds, if the timing was off or the points were
>     bouncing, etc.  Did your dyno guy give you that info?
>
>
>
>     That car was leaning out at high revs because the fuel pump couldn't
>     keep up with demand and the timing was breaking up.  He had me put in a
>     higher capacity fuel pump and change to electronic ignition with a new
>     coil and wires which solved those problems.  Then he rejetted the carbs
>     (Webers) and all was good.
>
>
>
>     I would take the car back to the dyno guy with the idea of him changing
>     timing and carb jetting to maximize power.  But first change the spark
>     plugs and fuel filter and check the timing to fix the simple things.
>
>
>
>     But other guys with 100x my knowledge will probably answer and you can
>     ignore what I write  :-)
>
>
>
>     Jim Oddie
>
>
>
>
>
>
>
>     -----Original Message-----
>     From: Garth Rodericks via DeTomaso <detomaso at poca.com>
>     To: npdrs <npdrs at maui.net>; Brent Stewart <bjbstewart at yahoo.com>;
>     DeTomaso Mail List <detomaso at poca.com>
>     Sent: Tue, Jul 1, 2014 10:12 am
>     Subject: [DeTomaso] FW: Moment of (sad) truth
>     Any idea what your cam specs are?  My stock late 72 351C with an
>     Edelbrock F351 intake, Mallory Unilite electronic ignition, and Hall
>     Big Bore headers with 90,000 original miles made 250 HP at the rear
>     wheels.  Check your tune. And do you have a new harmonic balancer on
>     that engine?  An old damper/balancer may have slipped, which means your
>     timing may be WAY off. Sounds like something is definitely amiss.
> On Tuesday, July 1, 2014 8:06
>   AM, Robert Stroj <[1]npdrs at maui.net> wrote:
>
> So, finally, my '71 Pantera got through all the import procedures and is now
> street legal in Europe/Germany!
> Car is in very good shape, zero rust anywhere, suspension feels very good to
> drive (height adjustable koni set), brakes work well (wilwood conversion),
> but there is something not right with the motor.
> Engine is a older 351C rebuild using original crankshaft and pistons. Some
> years later it was fitted with CHI 3V heads and intake system, SS valves,
> 780 Holley and GTS exhaust system.
> When driving the cart was pulling well, but definitely was not feeling as
> 400-500HP car; this is what I was sort of expecting after talking to person
> who rebuild the engine as well as previous owner...it did not really feel as
> 300HP car...
> I had a chance to put it on the dyno at the friend's garage and got the
> following graph (please see the attached image); this are graphs for
> adjusted power on the flywheel after recalculating looses between engine and
> wheels.
> What was really interesting is that he had a chance to test 2 other panteras
> recently; one was a client that had rebuilt engine using some "special
> parts", bt I am not sure of the actual spec while the other one was black
> GR4 replica that is currently listed for sale in Germany and was built by
> Braun Motorsport:
>
> [2][1]http://suchen.mobile.de/auto-inserat/detomaso-pantera-gruppe-4-m-hist-stra
> ss
> enzul-neuaufbau-neuried-bei-m%C3%BCnche/159513949.html?lang=de&pageNumber=1&
> __lp=1&scopeId=C&sortOption.sortBy=creationTime&sortOption.sortOrder=DESCEND
> ING&makeModelVariant1.makeId=7400&makeModelVariant1.searchInFreetext=false&m
> akeModelVariant2.searchInFreetext=false&makeModelVariant3.searchInFreetext=f
> alse&ambitCountry=DE&negativeFeatures=EXPORT
>
> So, finally, my engine did not even reach 250HP, another rebuild pantera
> motor did just over 300HP while Braun pantera did very nice 389HP; there is
> also Ford GT40 with racing motor in there; it did 410hp but at much higher
> RPM.
> The most impressive about the Braun car is how smooth the power curve is.
>
> So, now I am wondering where to go from here; could it be that it is as
> simple as wrong cam choice?
> If going to do a rebuild is there a good configuration someone could suggest
> that would use CHI3V heads and intake, as I already got those?
>
> As well, I had something strange happen twice with the gearbox; it got out
> of the 3rd gear by itself; would someone know if this could be due to any
> wrong linkage adjustment?
>
> Thanks, Robert
>
> References
>
>     1. [2]http://poca.com/mailman/listinfo/detomaso_poca.com
>     2. [3]http://suchen.mobile.de/auto-inserat/detomaso-pantera-gruppe-4-m-hist-s
> trass
>
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> References
>
>     1. http://suchen.mobile.de/auto-inserat/detomaso-pantera-gruppe-4-m-hist-strass
>     2. http://poca.com/mailman/listinfo/detomaso_poca.com
>     3. http://suchen.mobile.de/auto-inserat/detomaso-pantera-gruppe-4-m-hist-strass
>     4. mailto:DeTomaso at poca.com
>     5. http://poca.com/mailman/listinfo/detomaso_poca.com
>
>
>
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