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  #16 (permalink)  
Old 07-31-2012, 12:01 PM
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I don't care bout gas milage at all So I'm try the 750 I'm kinds broke now since I just bought the 3800 stall lol

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  #17 (permalink)  
Old 07-31-2012, 09:58 PM
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example of mine: My car,when I bought the car,ran a best time of 13.9 at 101 mph. All I did was swap in a 750 double pumper for a 600 double pumper and I ran 13.4 at 105.

Also of note,,, 650s/750s/850s used to work better than 600s/700s and 800s. I put a 700 double pumper on a 327 and it was a dog. I got my 750 double pumper off a 283 powered chevy2 I had before I got the Camaro. 600 cfm is not enough for a "good" 350
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Old 07-31-2012, 11:13 PM
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You want track proven? I've posted this so many times now that I'm sick of it but here goes. All steel '81 Camaro w/0.030" over 455 Pontiac, ported 6X, Performer intake, cam, TH400, 3.08 rear gears- 12.7 @ 107 mph. Carb was a Holley 4777. Picked up almost 2 tenths by changing to 3.31's.

Would his car pick up using a bigger carb? Possibly. But not by enough to compensate for the amount of missing performance- especially the lack of 60' time. A smaller carb could even help the 60' time.

I'm waiting to see what happens w/the new TC.
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Old 07-31-2012, 11:57 PM
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using 4781 base plate on a 4777 carb can make a very big improvement on a low powered car.Takes some tuning and possible booster venturi changes to optimise.I did that before.The dyno time cost more than just buying a race prepped carb.I also used a 660 center squirter and it had fabulous wfo performance but it was grotesque as a street carb.
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  #20 (permalink)  
Old 08-01-2012, 06:21 AM
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So should I get a 750 vacuum or 750 double pumper
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  #21 (permalink)  
Old 08-01-2012, 06:30 AM
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put the convertor in first and get fresh numbers.

I personally would use a single plane intake and a 750 double pumper.750 cfm is 750 cfm.same size carbs make similar amounts of HP.More racers will be able to help you tune a race oriented carb like a 750 double pumper
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  #22 (permalink)  
Old 08-02-2012, 08:14 PM
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Anybody got tips on how to seat the converter I can't get the last part to go in
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Old 08-02-2012, 09:26 PM
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Quote:
Originally Posted by cobalt327 View Post
You want track proven? I've posted this so many times now that I'm sick of it but here goes. All steel '81 Camaro w/0.030" over 455 Pontiac, ported 6X, Performer intake, cam, TH400, 3.08 rear gears- 12.7 @ 107 mph. Carb was a Holley.
You have to be joking.

You guys have really fast cars. These are full weight normal driving vehicles? My mothers accord weighs about 3600lb with the 4 cylinder, It is a aluminum can. It is hard to get an old GM full size down to 3600. Almost inpractical.

Using the scale at the land fill. It weighs your car at its actual weight. No door sticker, or advertised weights.

When I did the drag only build with 4.56 gears it would be at the hydraulic limit around 6300-6500rpm. Taking it up before the traps it would run out, and had to let off. Made it to 13 flat using the Mopar direct connection book 13sec 440 reciepe. Mopar 509 cam 3600 stall 4.56 gear in a 3800lbs 70 barracuda. I thought that was a fast package. Using a demon 750 DP.

A 600cfm never made more than 300hp NA.

I built a 355/th350 with the rpm complete heads and cam and intake and 750 carb 3000stall 4.10 build. It supposedly made 420hp, according to the mph it was about 268 rwhp.

My truck is super charged vortec sbc and probably makes 350hp at the flywheel. If you can get 1hp per inch NA that is fantastic. My NA stuff was around .8 to .85hp per inch, figured from the mph.

To dial in the carb we use a 4-5 gas probe at the collector. You turn the car wheels resting on a rollers with 500lbs of resistance strapped down with a fan . O2 Co's Nox A/f in parts per millioin ppm and tune accrording.

Last edited by spinn; 08-02-2012 at 09:42 PM.
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  #24 (permalink)  
Old 08-02-2012, 11:33 PM
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why would anyone aspire to get .8 hp per cubic inch? I feel 1.15 to 1.2 horse power per cube as being a decent and achievable goal with good road manners,like any modern engine offered here in north america. I believe 1.5 HP/cube is about the most I want to deal with and still drive it on week ends.Im talking normally aspirated engines,,,
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Old 08-03-2012, 06:40 AM
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V , its not like I was trying to limit my builds to that. It is how much they made.

A .85 hp per in NA engine is a hot engine. 1.2 hp per inch NA is not even realistic. It can be done at a premium. That 375hp/327 never made 375 real hp. Some people became dreamers, instead of builders/creators . I do like to read your reciepes.

Peaky power and a flat curve power are diffrent. You may get 400+ hp with a 350 single plane, single carb, big cam. A supercharged 350 with a mild cam is gonna walk it from the line. You will not catch up, off the line is were it is won.

So what increase the stall to 4000 shift a 6000+ and remove all driveability. Could be but thats not my way.
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Old 08-03-2012, 08:04 AM
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Spin,my latest project might fit what you describe,,,,might?My street car is a 1981 vette,so far changed almost everything.256/264 @ 050 roller cam.drive ability is very good after 1600 RPM.I can drive @ 45 MPH in O/drive and accelerate smoothly and very quickly. below 1600 rpm I need to go down a gear.The reason it will still respond well with that big of cam is the intake centre line is only 108 degrees. Im very very sure this engine exceeds the 1.2 horse power per cube that I feel is normal.If you have a calculator,plug in the numbers and see what you get?
specs,,10.75:1,cam 256/264@050,,420 lift x 1.6 intake/1.5 exhaust,,950 modified hp,vic junior(instead of super vic for lower RPM and smaller cam) 4.155 bore/4 stroke,dart 227 cnc ported heads with minor polishing,2.07 int valves/1.6 exhaust,,rocker shafts.callies light crank,wiseco pistons,cam is solid roller and 108 separation(square cam,more for road race)

let me know what you think it makes?
I am making a few changes and painting the car.I will chasis dyno it after all that.The engine has been on a dyno before installation,which is just a ball park because my headers and carb are different and I run full exhaust
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Old 08-03-2012, 08:05 AM
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heads flow 327 cfm on intake side,thats very important,,,
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  #28 (permalink)  
Old 08-03-2012, 11:24 AM
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Quote:
Originally Posted by vinniekq2 View Post
specs,,10.75:1,cam 256/264@050,,420 lift x 1.6 intake/1.5 exhaust,,950 modified hp,vic junior(instead of super vic for lower RPM and smaller cam) 4.155 bore/4 stroke,dart 227 cnc ported heads with minor polishing,2.07 int valves/1.6 exhaust,,rocker shafts.callies light crank,wiseco pistons,cam is solid roller and 108 separation

let me know what you think it makes?
I am making a few changes and painting the car.I will chasis dyno it after all that.The engine has been on a dyno before installation,which is just a ball park because my headers and carb are different and I run full exhaust
Calculator? You mean the track mph, or a engine dynometer. Anything else is bogus or close to. That is all race, and you could be making more than 1.2 per.

I like the cam 256 at .050 with .42 lobe , man that is not gonna work on the street with even a 454. Yes you can probably drive it . My oppinion that the valves do not stay closed long enough to have anything under 3-4000rpm.
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  #29 (permalink)  
Old 08-03-2012, 11:37 AM
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rofl,I lope along at 65 mph at 2100 ish rpm. That is not a huge cam. thats .420 lobe lift btw if you missed the info. so just over 600 lift exhaust and close to 640 lift intake. If you have used any roller cams you know how nice and smooth they are. This cam idles smoother than any 500 lift 300 (advertised) hydraulic flat tappet cam
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Old 08-03-2012, 11:41 AM
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also forgot to mention,the headers are step headers with 1 7/8" stepped to 2" with 3" collectors. Primary tubes that big require adapters to bolt them to the heads. I use Jere stahl headers and his adapters are different than hooker big tube headers,just in case someone needs to regasket their headers there are 2 sizes depending on adapters
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