Thanks for the reply, Steve. But, I considered the accelerator shot and
that can't be it. Let me describe the situation better. Interstate
cruise
is the most obvious.
So, there I am on the interstate cruising along at about 60mph. The
engine's revving and the mixture's doin' alright. If I press a little on
the accelerator smoothly to get up to 65 or 70, it goes way lean and holds
in a lean condition until I get up to the desired speed and ease out of
the
throttle a tad to hold it.
I'm not "kickin' it" to need the pump shot or so heavy that the vacuum
drops enough that I'd need the Power Valve; just a little more throttle.
If
I do continue to roll into the throttle for heavier acceleration, it don't
see the PV overcome the lean condition.
Perplexing, huh?
Drink
"Steve Austin" <saustin4@[EMAIL PROTECTED]
> wrote in message
news:45d79695$0$28119$4c368faf@[EMAIL PROTECTED]
> James Drinkwater wrote:
>
>> Hi Guys,
>> Got a Holley 650 double-pumper on "Dad's hotrod" with some probs
>> tuning. Upon depression of the throttle, my fuel/air ratio gauge shows
>> that the mixture goes way lean and the engine goes into lean misfire
and
>> dropped power. Eventually it richens back up as the RPMs slowly
>> increase. Not talking about the accelerator pump, just giving it a
>> little more gas while driving.
>> Bought the carb from my machinist in the original box in like-new
>> (visually) condition. Here's what's new and ruled out: high-volume
fuel
>> pump, fuel filter, fuel regulator and pressure gauge, float needles &
>> seats, jets (just to be sure), 6.5" power valve (like the original).
>> both squirters appear to pump fine but the problem occurs when you
slowly
>> roll into the throttle and it happens really quick (very throttle
>> sensitive).
>> It's a moderate, street performance SB Chevy that makes about 10.5"
>> vacuum at idle. I know the PV should move up to 8.5" but rolling into
>> heavy acceleration (vacuum below PV opening point) doesn't overcome the
>> lean condition either.
>> Two last things are that idle mixture is pretty un-responsive to idle
>> mixture screws, even when idle speed is as low as the engine will
>> reliably rev. Second, main jets were very, very rich at stock 67's
>> (primary) and still a tad on the rich side with 65's.
>> Dirty passage somewhere? Higher vacuum power valve needed and drill
>> the PVCR's? I'm a little stumped.
>> Best Regards,
>> Drink
>>
>> '87 TransAm (No computer controls)
>> Holley 650cfm double-pumper
>> Victor Jr. single plane
>> 186 heads, fully ****ted with 2.02 valves
>> 218/228 roller cam
>> 1.6 magnum rockers
>> 10:1 KB pistons
>> Mallory Comp9000 distributor
>> Hooker SuperComp headers
>> 3.73 gears
> Maybe you aren't talking about the accelerator pump, but you should be
> looking at it.
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