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Discussion Starter · #1 ·
357W
10.4:1
edelbrock performers 1.90/1.60
comp 262 cam
rpm air gap intake
thunder 650 vac
mild C4 trans


We advanced the timing a little and went to bigger jets, rods and lighter springs and ended up with 292.4hp and 318lb/ft








at peak power the motor is pulling -1.8 inHg and over -2.0 inHg above peak power

Is my 650cfm carb a restriction?
 

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Yes I would go with a holley 750. Thats what most chevy guys use on their 350's. I use a 650 holley on my 302.

<font size=-1>[ This Message was edited by: ujt389 on 4/12/06 7:57am ]</font>
 

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And the cam....
 

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IMO BG Sux !! Stick with Holley.......
 

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Discussion Starter · #8 ·
On 2006-04-12 13:36, dfree383 wrote:
IMO BG Sux !! Stick with Holley.......
From what I have heard and read about the BG's they are pretty much a tricked out holley

what is it that you don't like about them compaired to a holley?
 

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I just sent back a BG Speed Demon 650 DP and got a 750 Holley HP Street carb and it runs like a champ. I have a wide band O2 and could not tnue the BG carb at all. I do not recomend the BG carb at all.
 

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Laska50, just wondering what jets you were running in your Speed Demon 650DP. Also what engine are you feeding the now 750 Holley HP with??
As far as PhiberOptik's engine buildup, it looks like he would very happy with a 650 Speed Demon. From what I have heard and been told, the 750cfm carbs put out more HP but what the magazines and some builders don't tell ya is that the bottom end is really doggy and performance is only at it's best above 4,000 rpms.
I just sent my 750 Speed Demon back to http://www.4secondsflat.com and purchased a 650 Speed Demon Vacuum Secondary. Don Gould the owner, was very informative and has a vast amount of knowledge to share. He explained that my 347 Stroker (415HP/440TQ at the engine)would not be running at it's best with a 750 Speed Demon. He convinced me to go with the 650 for street ability and the best performance. He also shared with me that the 650 Speed Demon is newer technology and a better carb than the Holley 750 which is based on older technology. Check out his webpage, he knows his stuff. $400 for a new 650 Speed Demon.

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70 Mercury Cougar 347 Stroker(415HP/440TQ), Tremec 5 speed, Ford 9" w/3:55 gearing
Amsoil Full Synthetics Dealer----contact/email me about some "High Performance Oil"

<font size=-1>[ This Message was edited by: Spali32 on 4/13/06 2:12pm ]</font>
 

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Its a long story. I called BG and the tech line said to use a 650 DB. I also live at 5000ft. So I got the carb and changed everything but the air bleeds, which can't be changed on the speed demon, and still could not get it to run. I had the carb off about 100 times, it would not respond to cahnges consistantly. I talked to Don, but I already had the carb. So I sent it back and got the 750HP, and it shows on the o2 sensor changes in jetting, so I'm pleased with it.
 

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actually those are not bad numbers with the heads you have. They are preformers correct from Eddy ? RpM preformers would net you better results with the intake your running.

Also on the carb issue, people always want to say to go big on a carb..Thats incorect. Its better to always be "pulling" from a smaller carb than just being at the bowl from a to big carb. Yes while you may have a bigger HP no#, your accerleration and tq will suffer. When you race, its tq that counts.
 

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It looks like your matched up pretty close for the combo. What rear gear and tire size do you have? Is this a street or strip car?

<font size=-1>[ This Message was edited by: 63SportsCoupe on 4/21/06 9:23am ]</font>
 

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Gee Whizz...unless you weigh 800 lbs, you could run 11s all day long in that thing! My compliments on the "sleeper" factor


<font size=-1>[ This Message was edited by: 63SportsCoupe on 4/21/06 11:23am ]</font>
 

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On 2006-04-20 13:43, StangNinjak wrote:
Also on the carb issue, people always want to say to go big on a carb..Thats incorect. Its better to always be "pulling" from a smaller carb than just being at the bowl from a to big carb. Yes while you may have a bigger HP no#, your accerleration and tq will suffer. When you race, its tq that counts.
It may be "incorrect" for some applications, but not for all.

I would also disagree that "it's better to always be pulling".

If a carb is pulling in excess of 1.5" vacuum at WOT peak torque, it's overly restrictive.

Here's some info that sheds light on the subject: (Hold your cursor over the image until an icon appears in the lower right hand corner...click it for a larger view.)

http://www.fordmuscle.com/pictures/mstngjoe/AirFlowPower.jpg

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<font color="red">***New Project***</font>'89 LX 408, SCAT crank & H-beams, Probe pistons, AFR 205, Rawls SFT cam, Vic Jr intake, Pro Systems carb, UPR K & arms w/coil overs.....more to come!!!



<font size=-1>[ This Message was edited by: mstngjoe on 4/21/06 11:55am ]</font>
 

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@mstngjoe: This is true as well. I read that article before, and another one on the same topic. there are ways to make a big carb work on smaller CI engines true. But with the current combo he has, specificlally the heads, getting to big of a carb would be bad. I ask you, on a 351 engine engine, with TFS heads and cam, rpm Intake or stealth, what would be better ? A 670 carb, Holley SA or a 770 Holley SA ? Which would work better ?

<font size=-1>[ This Message was edited by: StangNinjak on 4/22/06 12:00am ]</font>
 

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You also have to remember that with a dual-plane intake you're virutally cutting your carb airflow in half. Cutting the plenum divider down, or adding an open spacer, will help by sharing some of the airflow of all 4 barrels to each plenum, but ultimately what's "too big" on a single plane could be "just right" on a dual plane. Just food for thought...
 

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On 2006-04-21 08:59, StangNinjak wrote:
@mstngjoe: ......I ask you, on a 351 engine engine, with TFS heads and cam, rpm Intake or stealth, what would be better ? A 670 carb, Holley SA or a 770 Holley SA ? Which would work better ?
I ran a Holley 750HP w/vac secondary (#0-82750) on a 331, AFR 185, Stealth, C4, 3.70 gear.

The thing ran like a scalded cat.

That was a street car that saw no track time at all.

I wouldn't put anything less than a 750 on the application in question.

But that's just me.


A smaller carb is adequate......not optimum for power though.
 

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A smaller carb is adequate and more street ability. A larger carb is great if you have your foot floored all the time, but it's a dog under 4,000 rpms.

_________________
http://www.spalisautodetailing.com/

70 Mercury Cougar 347 Stroker(415HP/440TQ), Tremec 5 speed, Ford 9" w/3:55 gearing
Amsoil Full Synthetics Dealer----contact/email me about some "High Performance Oil"

<font size=-1>[ This Message was edited by: Spali32 on 4/22/06 4:24pm ]</font>
 
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