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post #1 of 9 (permalink) Old May 25th, 13, 1:50 PM Thread Starter
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sam
 
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Carb questions

Trying to find out initially what jets to use. I have two carbs, one is Holley 750 vac sec 3310, has blocked power valve and 79 main jets. Other is an HP street, 750 DP, 75 front jets, with front power valve, markings on it are K 6 4, rear powervalve is blocked with 80 jets. Engine is 434 BB, made about 12-13 in vaccuum last I checked. It has been very rich running with the DP on it. How should I set either carb up to not run stinky rich? What size is that powervalve, what should I use and how can I tell if it's good? Car is mainly street driven with a yearly trip to the track. Thanks for any info, Sam

1967 Royal Plum, 434BB, AFR Heads, 3.90 gears, New Chris Straub Hyd Roller!, 200r4
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post #2 of 9 (permalink) Old May 25th, 13, 2:22 PM
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Jason
 
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Re: Carb questions

3310 Vac Secondary info:

http://www.holley.com/data/Products/...9934-3rev2.pdf

I would search the Holley website to find the correct factory settings, set the carb(s) to that and begin there.

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post #3 of 9 (permalink) Old May 25th, 13, 2:38 PM Thread Starter
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sam
 
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Re: Carb questions

Looking at tat info, my 3310 would have come with a 65 pv in front and 70 jets, which at this time are 79 with no pv....the 21 plate it says is equal to a 75 in the rear. so it looks like 79 front to 75 rear.

1967 Royal Plum, 434BB, AFR Heads, 3.90 gears, New Chris Straub Hyd Roller!, 200r4
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post #4 of 9 (permalink) Old May 25th, 13, 3:18 PM Thread Starter
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Re: Carb questions

So far unable to find out of the box jetting for 82751 HP Street 750 DP

1967 Royal Plum, 434BB, AFR Heads, 3.90 gears, New Chris Straub Hyd Roller!, 200r4
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post #5 of 9 (permalink) Old May 25th, 13, 3:19 PM
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Jason
 
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Re: Carb questions

Quote:
Originally Posted by scalise71 View Post
Looking at tat info, my 3310 would have come with a 65 pv in front and 70 jets, which at this time are 79 with no pv....the 21 plate it says is equal to a 75 in the rear. so it looks like 79 front to 75 rear.
I'd say changing just the primary jets to 70's and putting in the 6.5 pv would be a good place to start. There are a few different methods in PV selection on this site, so research and try a few. But you can't go wrong setting it to factory and working from there. At least it's at baseline.

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post #6 of 9 (permalink) Old May 25th, 13, 3:21 PM
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Re: Carb questions

most of the problem is likely from the PV plug. If you drive your vehicle anywhere but a racetrack it needs to have a working PV. A/F ratio requirements for cruise and power are very different, this is what the PV does. DPs are always pig rich at idle and cruise because they were designed for racing, not driving.

Put the carb or carbs back to as close to stock as you can them, try again.

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post #7 of 9 (permalink) Old May 25th, 13, 3:25 PM
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Jason
 
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Re: Carb questions

Quote:
Originally Posted by scalise71 View Post
So far unable to find out of the box jetting for 82751 HP Street 750 DP
I found from another site 75 primary, 80 secondary and 5.5 PV. Not sure if those are correct, I would call Holley and ask directly.

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post #8 of 9 (permalink) Old May 25th, 13, 3:43 PM
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Mark Whitener
 
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Re: Carb questions

The street HP has messed up calibration, the carb metering is set up like a 2 corner idle carb, except it's a 4 corner idle. The fix is in the link below.

http://racingfuelsystems.myfunforum....php?f=25&t=135

Mark Whitener

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post #9 of 9 (permalink) Old May 26th, 13, 6:04 PM Thread Starter
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sam
 
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Re: Carb questions

Thanks for all of the good info. Now I have a good starting point to sort things out, and I pulled both carbs apart, put the 3310 back on for now.

1967 Royal Plum, 434BB, AFR Heads, 3.90 gears, New Chris Straub Hyd Roller!, 200r4
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