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 Post subject: 2 tuning questions
 Post Posted: Fri Jun 15, 2012 7:00 pm 
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Joined: Sun Apr 23, 2006 5:41 am
Posts: 269
Location: Newville PA
I put a set of billet metering blocks on my 7320 dominator. QFT part number 34-4. Here is all the info on my tune up.

angle channel .159
kill bleed .028
e-hole -1 .028
e-hole -2 .000
e-hole -3 .028
e-hole -4 .000
pri jet Holley 85
sec jet Holley 94
pvcr .055
mab .026
iab .063
i jet .040
tsj .065
power valve 3.5

The transfer slots are just showing under the throttle blades. Idle screws are 1.5 turns out. The engine ildes fine from cold up to running temp. I did not set the idle screws by vacume,just set them at 1.5 turns out.
Here is my engine: 427 ci sbc, 15 to 1 compression, Brodix 18c heads, sheetmetal intake, 1.5 in Wilson spacer.

Here are my questions: The pvcr seems small,but the plugs do not look lean. A little tan with a ring near the top and one clean down at the bottom. (1)Is this a good starting point for the pvcr or should I go bigger?
(2) If I were to put in billet boosters (has stock annular boosters now) would I have to change my tune up any or just run it and see what happens?

Thanks Bob J


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 Post subject: Re: 2 tuning questions
 Post Posted: Sat Jun 16, 2012 7:09 am 
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Posts: 1422
Location: Florida
If the car idles well cold the mixture is a little on the rich side, adjust it for best idle warm. A carb should be a little cold natured. Aldo try going to .067 on the IAB and readjust the mixture, as long as it doesn't cause a light throttle or tip in stumble it will help keep the plugs clean at low speeds.

As far as the PVCR, you don't need the large spread on the jets with the PVCR so small. If you want to run a PV try to start the PVCR around the. 080 range, and run your primary jet at about a 90 to start. go up to 95 on the secondary and jet up or down on the dyno or track as needed.

And last, a billet booster in itself is worth no power, however some performance can be found for some engines with more smaller holes in the booster inserts. BLP has 12 and 16 hole boosters, and I tend to run the 16 hole most of the time. An engine with a very good induction and good distribution between cylinders will probably not see any significant difference, an engine with poor distribution will benefit the most.


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 Post subject: Re: 2 tuning questions
 Post Posted: Sat Jun 16, 2012 8:38 am 
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I'm going to add something I've found when running a PV especially if you don't have O2 sensors to check AFRs.

FIRST get the jet squared WITHOUT a PV in!! Jet up or down for best MPH with the jet squared THEN put in the PV and work back to that MPH number with the primary jet.

And last, IMHO an engine in a car running a transbrake really doesn't need a PV as you're either WFO or running on the primary T slots on the return road. The only place that a PV would "maybe" help would be during the burnout if you're feathering the throttle but even then that only takes a couple of seconds to complete. The only real reasons I see for running a PV is if you're foot braking or driving it on the street.

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 Post subject: Re: 2 tuning questions
 Post Posted: Sat Jun 16, 2012 7:18 pm 
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Joined: Sun Apr 23, 2006 5:41 am
Posts: 269
Location: Newville PA
First off I raced today at Beaver Springs Dragway a 1/4 mile track about an hour north of me. That track is a little higher above sea level than my normal track. The car was very easy to drive even cold. Just put it in gear and drive up to tech. It ran 7.81 off the trailer,7.84 spinning.7.82 and then first round 7.82. with a bad red light.

Ken,

I am going to go with what Mark said, only because I do not want to change too many things at one time. The carb is so close and so driveable that I hate to make alot of changes.

Bob J


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