Help me decide Holley 650 or 750
#178294
12/29/08 07:35 PM
12/29/08 07:35 PM
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Joined: Jul 2007
Posts: 406 Houma, Louisiana
twister360
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mopar
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OP
mopar
Joined: Jul 2007
Posts: 406
Houma, Louisiana
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Currently I have a built 360 Magnum motor in my 74 Duster. I have Magnum heads that have been mildly ported, a Comp Cam with 230* intake and 236* exhaust at .050 amd .544 lift on intake and .555 on exhaust,RPM air gap dual plane intake, with a Holley 3310 750 CFM vaccuum secondaries. The car has a 3200 stall converter in a 904 with TCI shift kit and a fresh rebuild of tranny,and 3.91 gears in a SG 8 1/4 rear end and Mickey Thompsons 275x60x15 ET street radials.
My problem is that the carb seems too rich. This combo was dynoed at 400 HP / 410 torque at the flywheel, but once installed in the car, there seemed to be too much fuel and has a strong smell of gas.
Is this too much carb for the motor? I have some that tell me to go to a Holley 4777 650 CFM, and the car will get better gas mileage and be faster at the track.
Which carb would you run and why? Thanks Moparts
My car 74 Duster mild 360/904/3.91 13.44/101.54
Son's car 75 Dart Sport 318/904/4.10 looking for a 360 or 408
2004 Dodge Ram 1500 Laramie 5.7
2010 Dodge Challenger R/T Classic B-5 6 speed
2010 Jeep SRT8 for the little wife
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Re: Help me decide Holley 650 or 750
[Re: twister360]
#178295
12/29/08 07:46 PM
12/29/08 07:46 PM
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Joined: Jan 2003
Posts: 9,826 las vegas
70AARcuda
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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check your vacuum ...and then check your power valve in the holley...
also...adjust your idle mixture screws..
check your float levels too...
i have a similar cam in my 73 duster and it runs great with a 750 vacuum holley..
Last edited by 70AARcuda; 12/29/08 07:47 PM.
Tony
70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: Help me decide Holley 650 or 750
[Re: 70AARcuda]
#178297
12/29/08 08:19 PM
12/29/08 08:19 PM
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Joined: Jul 2007
Posts: 406 Houma, Louisiana
twister360
OP
mopar
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OP
mopar
Joined: Jul 2007
Posts: 406
Houma, Louisiana
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I have checked the power valve and it is okay. Where should the level be in the bowls? What should I look for when checking the vaccuum? Where is a good starting point on the mixture screws? Thanks for the info.
My car 74 Duster mild 360/904/3.91 13.44/101.54
Son's car 75 Dart Sport 318/904/4.10 looking for a 360 or 408
2004 Dodge Ram 1500 Laramie 5.7
2010 Dodge Challenger R/T Classic B-5 6 speed
2010 Jeep SRT8 for the little wife
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Re: Help me decide Holley 650 or 750
[Re: 70AARcuda]
#178299
12/29/08 08:30 PM
12/29/08 08:30 PM
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Anonymous
Unregistered
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Anonymous
Unregistered
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adjust mixture screws 1/4 turn at a time for highest vacuum. then reset idle speed
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Re: Help me decide Holley 650 or 750
[Re: twister360]
#178301
12/29/08 08:46 PM
12/29/08 08:46 PM
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Joined: Mar 2003
Posts: 4,929 Tri-Cities, Washington
VITC_GTX
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master
Joined: Mar 2003
Posts: 4,929
Tri-Cities, Washington
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I have your twin...
I have a 360 Magnum in my '71 Demon. Stock bottom end with a 226/238 @ .050" with .520" lift. Eddy Air-gap intake, 727 with ~3500 converter and 3.91s. My best is 12.76 @ 104 mph. I am currently running an Eddy 650 right out of the box. I never even touched the idle screws. With that said, I am considering going to a 750.
Last edited by VITC_GTX; 12/29/08 08:46 PM.
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Re: Help me decide Holley 650 or 750
[Re: twister360]
#178302
12/29/08 08:49 PM
12/29/08 08:49 PM
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Joined: Jan 2003
Posts: 5,443 Indiana
YO7_A66
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master
Joined: Jan 2003
Posts: 5,443
Indiana
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""I have checked the power valve and it is okay.""
What is your in-gear vacuum reading with your foot on the brake (like you are at a stop sign)?
What number is your power valve?
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
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Re: Help me decide Holley 650 or 750
[Re: Mr.Yuck]
#178304
12/29/08 09:43 PM
12/29/08 09:43 PM
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Joined: Jan 2003
Posts: 9,826 las vegas
70AARcuda
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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the holley 3310 750 vacuum holley is an universal carb...it will need some tuning to make it work..and it will work great...
just need to check what number power valve u got...it needs to be something around a 6.5...and adjust the idle mixture...
the jetting will be close..
my 73 duster ran 3 tenth quicker will a 750 dp then the 750 vacuum...but driving every day i run the vacumm carb..
Tony
70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: Help me decide Holley 650 or 750
[Re: 70AARcuda]
#178305
12/29/08 10:15 PM
12/29/08 10:15 PM
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Joined: Jul 2007
Posts: 406 Houma, Louisiana
twister360
OP
mopar
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OP
mopar
Joined: Jul 2007
Posts: 406
Houma, Louisiana
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The power valve is 6.5. If the vac drops below 6.5 will this cause the PV to open? Where would I find step by step directions for setting this carb? Thanks
My car 74 Duster mild 360/904/3.91 13.44/101.54
Son's car 75 Dart Sport 318/904/4.10 looking for a 360 or 408
2004 Dodge Ram 1500 Laramie 5.7
2010 Dodge Challenger R/T Classic B-5 6 speed
2010 Jeep SRT8 for the little wife
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Re: Help me decide Holley 650 or 750
[Re: twister360]
#178306
12/29/08 10:17 PM
12/29/08 10:17 PM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
The power valve is 6.5. If the vac drops below 6.5 will this cause the PV to open? Where would I find step by step directions for setting this carb? Thanks
try holley's web site. I'm sure they have step by step instructions.
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Re: Help me decide Holley 650 or 750
[Re: Dave Watt]
#178308
12/29/08 10:38 PM
12/29/08 10:38 PM
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Joined: Jul 2007
Posts: 406 Houma, Louisiana
twister360
OP
mopar
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OP
mopar
Joined: Jul 2007
Posts: 406
Houma, Louisiana
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Thanks for all the help. What is the purpose of the PV and how does it operate? If manifold pressure drops to a certain point, will the PV open? The last time I checked my manifold pressure it was above 10 inches at idle. Don't know what it would be at WOT or part throttle.
My car 74 Duster mild 360/904/3.91 13.44/101.54
Son's car 75 Dart Sport 318/904/4.10 looking for a 360 or 408
2004 Dodge Ram 1500 Laramie 5.7
2010 Dodge Challenger R/T Classic B-5 6 speed
2010 Jeep SRT8 for the little wife
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Re: Help me decide Holley 650 or 750
[Re: twister360]
#178309
12/29/08 10:43 PM
12/29/08 10:43 PM
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Joined: Jan 2003
Posts: 24,562 Brookeville, Md
Mr.Yuck
Not enough dumb comments...yet
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Not enough dumb comments...yet
Joined: Jan 2003
Posts: 24,562
Brookeville, Md
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Quote:
Thanks for all the help. What is the purpose of the PV and how does it operate? If manifold pressure drops to a certain point, will the PV open? The last time I checked my manifold pressure it was above 10 inches at idle. Don't know what it would be at WOT or part throttle.
AT WOT it should be ZERO... usually you set your PV from idle vacuum.
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Re: Help me decide Holley 650 or 750
[Re: Mr.Yuck]
#178310
12/29/08 10:52 PM
12/29/08 10:52 PM
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Joined: Jan 2003
Posts: 9,826 las vegas
70AARcuda
master
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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behind the power valve is two small passages that provide additional fuel as a power enrichment circuit...
if u floor the gas....vacuum drops to zero...power valve opens and provides additional gas...
most holleys with two metering block in them ...the primaries will be about 8 to 10 jets leaner then the secondaies.
the pvrc provides that additional fuel....so u can cruise on a leaner mixture...then get more gas went u floor it...
Tony
70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: Help me decide Holley 650 or 750
[Re: 70AARcuda]
#178311
12/29/08 10:53 PM
12/29/08 10:53 PM
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Joined: Jan 2003
Posts: 9,826 las vegas
70AARcuda
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master
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las vegas
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http://www.mortec.com/carbtip1.htmscroll down the page...has info on power valves.
Tony
70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: Help me decide Holley 650 or 750
[Re: 70AARcuda]
#178312
12/29/08 10:56 PM
12/29/08 10:56 PM
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Joined: Jan 2003
Posts: 9,826 las vegas
70AARcuda
master
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master
Joined: Jan 2003
Posts: 9,826
las vegas
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Last edited by 70AARcuda; 12/29/08 11:05 PM.
Tony
70 AARCuda Vitamin C 71 Dart Swinger 360 10.318 @ 128.22(10-04-14 Bakersfield) 71 Demon 360 10.666 @122.41 (01-29-17 @ Las Vegas) 71 Duster 408 (10.29 @ 127.86 3/16/19 Las Vegas)
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Re: Help me decide Holley 650 or 750
[Re: twister360]
#178313
12/30/08 07:30 AM
12/30/08 07:30 AM
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Joined: Jan 2003
Posts: 5,443 Indiana
YO7_A66
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master
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Posts: 5,443
Indiana
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""The last time I checked my manifold pressure it was above 10 inches at idle.""
Was this in neutral or in gear idle? If you have an automatic, you can tune the carb to get it close in N, but then you need to finish tuning it with the car in gear and a vacuum gage hooked up.
1970 YO7 A66 [Canadian Export] F8 Challenger 340 (Currently in shop for stroker assy.)
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