[DeTomaso] ***SPAM*** Re: Carb hesitation on level ground at cruise

[Asa Jay Laughton]

I wish I did have a spare carb ready to bolt on.  Best I’ve got is a Holley 850 collecting dust on a shelf awaiting a rebuild (someday).

I don’t recall a vacuum advance on this distributor.  But now I’m going to investigate more because it should if it’s got a carb, unless there is a crank trigger wheel for something else.   

Plenty of ideas to get me checking things again.

Thank you.
Asa  Jay


Sent via radio waves

> On Jul 31, 2024, at 07:55, Will Kooiman <will.kooiman at gmail.com> wrote:
> 
> It actually sounds like the timing is off.  Does it have vacuum advance?
> 
> 1) If it has vacuum advance, try unplugging it to see if it improves.
> 2) Can you try a known good carburetor?
> 
> 
> On 7/31/24, 1:09 AM, "DeTomaso on behalf of Asa Jay Laughton via DeTomaso" <detomaso-bounces at server.detomasolist.com <mailto:detomaso-bounces at server.detomasolist.com> on behalf of detomaso at server.detomasolist.com <mailto:detomaso at server.detomasolist.com>> wrote:
> 
> 
> I have successfully (for the most part) tuned an Electromotive system. Still some things to learn there but it sure ran a lot better after I tuned it.
> 
> 
> I agree, carbs are fairly simple but there are some complexities. I’m not so much lost as I may be leading you to believe.
> 
> 
> Asa Jay
> 
> 
> Sent via radio waves
> 
> 
>> On Jul 30, 2024, at 20:55, Mike Drew <mikeldrew at aol.com <mailto:mikeldrew at aol.com>> wrote:
>> 
>> AJ,
>> 
>> If you are a bit lost with a carb I think you will be completely in the woods with injection. A carb is an extremely simple device by comparison.
>> 
>> Smart people, chime in!
>> 
>> Mike
>> 
>> 
>> Sent from my iPad
>> 
>>>> On Jul 30, 2024, at 20:45, Asa Jay Laughton via DeTomaso <detomaso at server.detomasolist.com <mailto:detomaso at server.detomasolist.com>> wrote:
>>> 
>>> Owner has asked if we could fix all problems with fuel injection. I’m not a fan of saying that because I know a well tuned carb can be just as good as well tuned EFI.
>>> 
>>> If the owner persists, what is the collectives opinions on various EFI systems out there today?
>>> 
>>> Thank you,
>>> Asa Jay
>>> 
>>> Sent via radio waves
>>> 
>>>>> On Jul 30, 2024, at 20:37, Asa Jay Laughton via DeTomaso <detomaso at server.detomasolist.com <mailto:detomaso at server.detomasolist.com>> wrote:
>>>> 
>>>> Hi all,
>>>> I'm working with a PIM 427 Hammer (stroked Windsor) in a Pantera. This has a Demon carb on it. I don't know what it has for jets. I know it runs a little rich.
>>>> 
>>>> Here is my situation and in a bit of humility, am stumped at the moment. Sam and I just took it out for a long test drive and it has problems on leverlk ground, no load, cruising mode.
>>>> 
>>>> It idles at about 800 rpm, a bit lumpy but starts right up cold, doesn't die, no choke (no choke on the Demon carb).
>>>> It revs easily and pulls away from a stop sign beautifully.
>>>> Under load, moderate throttle or foot to the floor, it runs great.
>>>> Off throttle, engine braking, it runs fine, though it doesn't burbble like I would expect
>>>> Uphill great, downhill not so much (that cruise position of the foot on the go-pedal)
>>>> On level ground, 5th gear, holding cruise at 60 MPH at around 2,000 rpm, it hesitates, jerks, feels like it's misfiring.
>>>> Same when in say 4th, holding cruise at a higher rpm but no load either with go-pedal down, or engine braking
>>>> It does this hesitation at nearly any rpm from 1,500 to 3,500 only when holding cruise speed, not when accelerating (even mildly)
>>>> 
>>>> I'm thinking the problem is the idle mixture and speed settings. I'm thinking the throttle plates might be closed wee bit too much and idle mixture is compensating. When the throttle is at off-idle, at cruise, the transfer ports aren't giving enough gas, or maybe it's air. Trouble is there is no AF gauge on it, and my portable can only be stuffed in one of four exhaust tips.
>>>> 
>>>> <sigh> so I'm asking for the collectives opinions, I know there are some good ones out there. I figure I need to re-check timing, advance, and carb tune again.
>>>> 
>>>> Thoughts?
>>>> Thank you,
>>>> Asa Jay
>>>> 
>>>> --
>>>> Asa Jay Laughton - W7TSC, MSgt, USAFR, Retired
>>>> Spokane County ARES-RACES-ACS EC/RO
>>>> ******************************
>>>> https://w7tsc.org <https://w7tsc.org>
>>>> https://www.teampanteraracing.com <https://www.teampanteraracing.com>
>>>> 
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