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750 carbs on 700hp motors
#1501000
09/14/13 01:26 AM
09/14/13 01:26 AM
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Joined: Jan 2007
Posts: 8,042
Mt Morris Michigan
mopar dave
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Mt Morris Michigan
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how do people get 750 carbs to support 700hp? I had a conversation today with john calvert. he tells me my poor 60' is not the fault of the chassis as it has no tire spin on launch. he suggests a smaller carb than my 950 bigs. john says his 700hp motor in his mustang has a 735cfm holley on it and runs 9.56@136. how is that possible?
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Re: 750 carbs on 700hp motors
[Re: mopar dave]
#1501003
09/14/13 08:03 AM
09/14/13 08:03 AM
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Joined: Jan 2003
Posts: 10,011
Frostbitefalls MN (Rocky&Bullw...
gregsdart
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If that car that made 700 hp with a 735 cfm carb was a stocker motor, then it has the ultimate in tricks to make power in the first place. There is a whole lot of improvements that will help reduce drag that aren't often done in a bracket build, which basically sets free a lot of power, thereby making a too small for the application carb look good.
Another thing to consider is the carb fuel curve, and if the way it atomizes fuel is right for your application. Some carbs don't atomize fuel properly for certain combinations. Every motor build and its application is a bit different, and sometimes there is good power to be found in just a different carb, even of the same size.
I haven't done much with carbs, but built a 475 motor using a juice cam and unported 440-c heads made over 600 hp on alky using a box stock Holley 750 alky carb. For what it was, it ran very well. A much bigger carb might have shown as much as 40 hp improvement though.
8..603 156 mph best, 2905 lbs 549, indy 572-13, alky
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Re: 750 carbs on 700hp motors
[Re: BradH]
#1501007
09/14/13 10:49 AM
09/14/13 10:49 AM
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Joined: Jan 2003
Posts: 11,720
Portage,michigan
B3422W5
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Its rare in a smallblock stroker motor for large carbs not to show ET gains over smaller carbs.
I have tried 5 or 6 different carbs on various stroker motors and found almost all the time the motor always liked the bigger carb over the smaller carb.
Lone exception being a 1025rs race demon ET'ed as well as a custom 1100 dominator did.
950 is a very solid choice on a mid range stroker like you have.
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8
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Re: 750 carbs on 700hp motors
[Re: mopar dave]
#1501010
09/14/13 11:23 AM
09/14/13 11:23 AM
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Joined: Jan 2003
Posts: 11,720
Portage,michigan
B3422W5
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I Live Here
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Dave.....if you don't mind what is your exact combo again??
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8
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Re: 750 carbs on 700hp motors
[Re: B3422W5]
#1501011
09/14/13 11:28 AM
09/14/13 11:28 AM
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Joined: Jan 2007
Posts: 8,042
Mt Morris Michigan
mopar dave
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Mt Morris Michigan
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most of it is posted above,heads flow [Email]325@.700[/Email], cam is a 106 lda [Email]installes@100.5[/Email], 950 bigs/1.400 venture=850 main body
Last edited by mopar dave; 09/14/13 06:16 PM.
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Re: 750 carbs on 700hp motors
[Re: mopar dave]
#1501012
09/14/13 11:39 AM
09/14/13 11:39 AM
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Joined: Dec 2009
Posts: 20,640
in a cattle trailer down by th...
Guitar Jones
Paddle faster! I hear banjo music!
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Paddle faster! I hear banjo music!
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in a cattle trailer down by th...
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Some more rear gear might help the 60', I wouldn't use a smaller carb, you may be able to use a 1050 Dominator on that combo. I have more compression (12.3) than you and my cam is 276/284 duration. About the same stall with 4.86 gears and a 32" tall tire. I'm using two 750's on a TR. I took the low gear out of the 904 and it still runs the same, just not as violent on the leave. My car is probably lighter than yours though at about 2780 with me in it.
"Follow me the wise man said, but he walked behind"
'92 D250 Club Cab CTD, 47RH conversion, pump tweaks, injectors, rear disc and hydroboost conversion.
'74 W200 Crew Cab 360, NV4500, D44, D60 and NP205 divorced transfer case. Rear disc and hydroboost conversion.
2019 1500 Long Horn Crew Cab 4WD, 5.7 Hemi.
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Re: 750 carbs on 700hp motors
[Re: mopar dave]
#1501013
09/14/13 11:40 AM
09/14/13 11:40 AM
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Joined: Mar 2006
Posts: 9,856
MI, usa
dvw
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Quote:
john calvert looked at my vid and says theirs no more tuning in the chassis as its doing what it should and no tire spin. he suggests issue is somewhere else, carb, convertor, rear gear, tranny gear.
You're in the same boat as me with a different combo. My 64 Belvedere runs 9.30/9.40@144/145 with mid 1.3 60s. No tire spin. In my case It could be carbs( 2 750 eddy) ,cam,converter,gear,. The bottom line for both of us is not enough low end torque to the tires. How do we improve? That is the million dollar question. I'm asking myself do I really want to give up a pretty quick great hooking combo with a relatively small (10.5) tires? I never thought I could run competitive local track prep bracket races with this type of car. I was wrong.
My 2 cents
Doug
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Re: 750 carbs on 700hp motors
[Re: mopar dave]
#1501014
09/14/13 11:44 AM
09/14/13 11:44 AM
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Joined: Jan 2003
Posts: 11,720
Portage,michigan
B3422W5
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I Live Here
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Portage,michigan
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60 foot is generally related to hook and torque to the ground.
Based on your combo I would guess your car should 60 foot about 1.40-1.42 or so....
car makes good mph for the Et so its making good horsepower. my opinion may differ from some, but if that was my car I would suspect the convertor flashes too high. I would think 5000 flash would be closer to optimal. how/what rpm do you launch the car at?
My w5 422 convertor flashed 5400 and I thought that was perfect. that was with a 273/280 roller and 13 to 1 compression. I would expect your torque peak to be somewhat lower than that. 5500 SHOULD be well past where that motor is making peak torque IMO.
have you ever tried a 4 hole spacer on top of that indy intake? those intakes are huge, make good upper end horsepower, a 4 hole might generate more lower end torque.
Gearing,etc seems like a non issue.
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8
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Re: 750 carbs on 700hp motors
[Re: mopar dave]
#1501015
09/14/13 11:48 AM
09/14/13 11:48 AM
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Joined: Jan 2003
Posts: 9,876
Weddington, N.C.
Streetwize
master
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master
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Weddington, N.C.
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Dave,
I just talked to Tim at Bullet and order the same lobes cut on a 108 and I'm putting it in at 104. 131 MPH for that weight of car I would think is pretty well close to optimized power wise
For your combo (especially the weight) I'm not sure I'd change very much other than maybe tire compound and pressure, with 5500 stall I'm not seeing how a smaller carb is gonna improve the 60' other than maybe tweaking the secondary cam shot.
What heads are you running? The Victor 340, I'm assuming it's ported and not holing back the heads and you are running a 2" spacer on it? The HVH tapered seems to work pretty well combined with plenum work, distribution is very good for what it is.
Cuda notches have great hook, I'd try upping tire pressure first to see if you can get it to spin, maybe try a smaller contact patch first.
Last edited by Streetwize; 09/14/13 11:51 AM.
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Re: 750 carbs on 700hp motors
[Re: Streetwize]
#1501017
09/14/13 11:57 AM
09/14/13 11:57 AM
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Joined: Jan 2003
Posts: 11,720
Portage,michigan
B3422W5
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I Live Here
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Portage,michigan
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Quote:
Dave,
I just talked to Tim at Bullet and order the same lobes cut on a 108 and I'm putting it in at 104. 131 MPH for that weight of car I would think is pretty well close to optimized power wise
For your combo (especially the weight) I'm not sure I'd change very much other than maybe tire compound and pressure, with 5500 stall I'm not seeing how a smaller carb is gonna improve the 60' other than maybe tweaking the secondary cam shot.
I think he is running an indy intake.....which is why I thought a 4 hole, or like you said a tapered spacer might make more torque
What heads are you running? The Victor 340, I'm assuming it's ported and not holing back the heads and you are running a 2" spacer on it? The HVH tapered seems to work pretty well combined with plenum work, distribution is very good for what it is.
Cuda notches have great hook, I'd try upping tire pressure first to see if you can get it to spin, maybe try a smaller contact patch first.
I think he said he is running an indy intake...hence the 4 hole, or like you said a tapered spacer might help.
Last edited by B3422W5; 09/14/13 12:00 PM.
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Re: 750 carbs on 700hp motors
[Re: B3422W5]
#1501018
09/14/13 12:11 PM
09/14/13 12:11 PM
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Joined: Jan 2003
Posts: 9,876
Weddington, N.C.
Streetwize
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master
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Weddington, N.C.
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Don, That's right, my bad I think Dave's got the Indy/Indybrock top end on it, I was thinking Vic for some reason....was out working in the yard early (beautiful fall day in Charlotte)...guess I had my coffee real late this morning 
Last edited by Streetwize; 09/14/13 12:13 PM.
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Re: 750 carbs on 700hp motors
[Re: Streetwize]
#1501019
09/14/13 12:14 PM
09/14/13 12:14 PM
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Joined: Jan 2003
Posts: 11,720
Portage,michigan
B3422W5
I Live Here
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I Live Here
Joined: Jan 2003
Posts: 11,720
Portage,michigan
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Quote:
Don,
That's right, my bad I think Dave's got the Indy/Indybrock top end on it, I was thinking Vic for some reason.
I think he has the " big" indy heads on it if they are flowing 320+....those are relatively " big" with a large intake plenum, and he doesn't have a lot of compression...I would think anything that makes things " smaller" will help 60 foot. Heck, it might even 60 foot better with mufflers on it 
Last edited by B3422W5; 09/14/13 12:16 PM.
69 Dart GTS A4 Silver All steel, flat factory hood, 3360race weight
418 BPE factory replacement headed stroker, 565 lift solid cam
Best so far, 10.40 @127 1/4
1.41 best 60 foot
6.60 at 103.90 1/8
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