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Re: How to identify a Holley power valve?
[Re: DaveRS23]
#1825092
05/12/15 04:53 PM
05/12/15 04:53 PM
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Joined: Oct 2004
Posts: 1,074
So Cal, USA
Fab64
OP
super stock
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OP
super stock
Joined: Oct 2004
Posts: 1,074
So Cal, USA
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I appreciate all the input, guys. The car already has a vacuum gauge. I also have a wide-band A/F gauge and sensor that I used when tuning my Barracuda. I will have a bung installed in this car, so I'll be able to see exactly what's going on.
Unfortunately, I had already removed the front carb before I read Robert's post yesterday. Since the fuel lines are such a pain to work with (i.e. I don't want to do it again!), I'm going to take a leap of faith, and install a 6.5 PV before buttoning everything back up. The car does not currently have any stumble issues, but it does have some pinging at higher rpm's while under heavy acceleration. I'm hoping the larger PV will help to lessen, or eliminate, this. If it helps, great. Otherwise, I'll have to go from there. At least, I will possibly avoid having to R&R everything again.
FWIW, here are the specs:
413 RB, w/10.1:1 compression
Cam is a .480/.480 lift, 236 duration at .050, lobe center is 108*
Timing is set at 36* total, all in at 3,000 RPM. Initial is 16*
Right now, my vacuum gauge reads 11-12" Hg at idle (950 RPM) in neutral. According to PO, in Drive with brake on, it's around 6" Hg. At cruise, around 20" Hg.
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Re: How to identify a Holley power valve?
[Re: Fab64]
#1825121
05/12/15 05:31 PM
05/12/15 05:31 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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The car does not currently have any stumble issues, but it does have some pinging at higher rpm's while under heavy acceleration. I'm hoping the larger PV will help to lessen, or eliminate, this. If the current PV is already open when the pinging start a larger one (opening earlier) would not have an effect on it cuz it'd already be enriched (if I read that right). Ideal would be more octane otherwise experiment with a slightly heavier spring combo and or shortening the slots slightly depending on your total right now
live every 24 hour block of time like it's your last day on earth
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Re: How to identify a Holley power valve?
[Re: mopars4ever]
#1825131
05/12/15 05:56 PM
05/12/15 05:56 PM
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Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
RapidRobert
Circle Track
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Circle Track
Joined: Nov 2003
Posts: 36,041
Lincoln Nebraska
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Me too (that it is less about the idle circuit) but where you want it to tip in
live every 24 hour block of time like it's your last day on earth
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Re: How to identify a Holley power valve?
[Re: Fab64]
#1825316
05/12/15 10:36 PM
05/12/15 10:36 PM
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Joined: Jan 2003
Posts: 13,097
Benton, IL.
DaveRS23
Master of nothing...
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Master of nothing...
Joined: Jan 2003
Posts: 13,097
Benton, IL.
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I appreciate all the input, guys. The car already has a vacuum gauge. I also have a wide-band A/F gauge and sensor that I used when tuning my Barracuda. I will have a bung installed in this car, so I'll be able to see exactly what's going on.
Unfortunately, I had already removed the front carb before I read Robert's post yesterday. Since the fuel lines are such a pain to work with (i.e. I don't want to do it again!), I'm going to take a leap of faith, and install a 6.5 PV before buttoning everything back up. The car does not currently have any stumble issues, but it does have some pinging at higher rpm's while under heavy acceleration. I'm hoping the larger PV will help to lessen, or eliminate, this. If it helps, great. Otherwise, I'll have to go from there. At least, I will possibly avoid having to R&R everything again.
FWIW, here are the specs:
413 RB, w/10.1:1 compression
Cam is a .480/.480 lift, 236 duration at .050, lobe center is 108*
Timing is set at 36* total, all in at 3,000 RPM. Initial is 16*
Right now, my vacuum gauge reads 11-12" Hg at idle (950 RPM) in neutral. According to PO, in Drive with brake on, it's around 6" Hg. At cruise, around 20" Hg.
As Robert suggested, the PV change is unlikely to have any positive impact. It is possible that the 36* total advance might be a little much. 32* to 34* might be better without evidence to the contrary. If the gearing and combo will allow, all-in by 2,000-2,500 should improve that area some. And that cam would probably like more lead. 20*-24* might improve the in-gear idle vacuum. Big blocks really respond to quicker timing. Get it in as fast as it will take it. The 499" in my Cuda has 28* at idle and is all-in by 1,800. And you may consider rubber lines to your carbs. It will cost a few bucks to do, but makes it much easier to dis-assemble them for tuning. And tuning usually takes several dis-assemblies. I never install the hard lines until I am comfortable that I won't need to pull one apart to tune.
Master, again and still
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Re: How to identify a Holley power valve?
[Re: RapidRobert]
#1825398
05/13/15 12:06 AM
05/13/15 12:06 AM
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Joined: Oct 2004
Posts: 1,074
So Cal, USA
Fab64
OP
super stock
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OP
super stock
Joined: Oct 2004
Posts: 1,074
So Cal, USA
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The best advice is to just mount a vacuum gauge in your car and watch it as you drive around. You'll quickly figure out when you want a PV open and then you can select that number and install it. that & make sure the rest of the carb subsystems are spot on incl the AP cuz it it ain't right then it might confuse you with a bog etc. Want IMMEDIATE tip in/correct nozzle "AP" = accelerator pump?? As Robert suggested, the PV change is unlikely to have any positive impact.
It is possible that the 36* total advance might be a little much. 32* to 34* might be better without evidence to the contrary. If the gearing and combo will allow, all-in by 2,000-2,500 should improve that area some. And that cam would probably like more lead. 20*-24* might improve the in-gear idle vacuum. Big blocks really respond to quicker timing. Get it in as fast as it will take it. The 499" in my Cuda has 28* at idle and is all-in by 1,800.
And you may consider rubber lines to your carbs. It will cost a few bucks to do, but makes it much easier to dis-assemble them for tuning. And tuning usually takes several dis-assemblies. I never install the hard lines until I am comfortable that I won't need to pull one apart to tune. Ok, I will put everything back together, get my A/F gauge working, and do more testing before making any changes. And thanks for the suggestion about rubber lines; that will definitely make things much easier. Do you happen to have a picture of yours with rubber lines?
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Re: How to identify a Holley power valve?
[Re: RapidRobert]
#1825524
05/13/15 09:27 AM
05/13/15 09:27 AM
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Joined: May 2003
Posts: 15,487
Florida
scratchnfotraction
I Live Here
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I Live Here
Joined: May 2003
Posts: 15,487
Florida
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Me too (that it is less about the idle circuit) but where you want it to tip in me 3 very interesting indeed. I can see where I need to make a couple changes already. I need to move my gauge in the cab to see what it is doing at cruz and tip in.
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Re: How to identify a Holley power valve?
[Re: Fab64]
#1825601
05/13/15 10:38 AM
05/13/15 10:38 AM
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Joined: Jan 2003
Posts: 13,097
Benton, IL.
DaveRS23
Master of nothing...
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Master of nothing...
Joined: Jan 2003
Posts: 13,097
Benton, IL.
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"And thanks for the suggestion about rubber lines; that will definitely make things much easier. Do you happen to have a picture of yours with rubber lines?"
Sorry no pics. But I use rubber lines to the bowls on all my carbs while I am tuning. And when it is possible to remove the bowls with the carb still on the intake, I use longer hoses so that I can pull the bowl and not even remove the line from the bowl.
Just trying to make things quicker and easier plus not mess up the fittings.
Master, again and still
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