I've got a 750DP to put on my new mill, but the guy at the shop that just did my headwork said that I would probably want a bigger carb before long. I was wanting you guys input on this as most posts I've read have said that a 750DP would support alot of HP. Here's my combo:

454 .30 over (should be 10/1 static compression)
SRP .100 dome pistons
GM dimple rods
Isky Z-33 Solid .560/.560 Duration @ 50 250/250 Lobe Center: 108°
702 closed chambered heads, 2.19's and 1.88's, ported and unshrouded. 100cc's after work performed.
Performer RPM intake
Hooker 2" primaries
3" exhaust with H pipe and flowmasters

Do I need more carb?

No..you'll be fine with a 750 double pumper..

Chris,

Thanks for the reply. Did you get my email?

If I may I would like to agree with Mr 4 Speed on the 750 CFM carb.... plenty of 10 sec cars out there in the world running single 750 carbs. graemlins/beers.gif

Purs,that is my work email address..I will check it on Monday morning..

I'm running a 750dp right now and the only difference that I noticed is that I had to jet down the 750dp compared to the 850dp. graemlins/waving.gif

JRS70LS5 that's a sweet 70! graemlins/thumbsup.gif Do you have any ET's as it looks like your combo is very similar to mine.

My 540 put out 640hp with a small cam dp intake and a speed demon 750..so id say you are good

I used to run a tunnel ram and two 600cfm's on a .060 396 with 12.5:1 CR. I took it of because it just wasn't working for a daily driver.I put on a 750 cfm DP and was never realy happy with it. It ran great but never pushed me back in the seat like the two 600cfm's did. I'd say go bigger than 750 cfm, especialy with a 454.

Purs no time slip yet but there will be soon!I remember reading a post by Chris_69_ss he ran a 750DP before he bought a 950HP and his et increase was minimal,just couldn't see spending that kind of money for a carb that would give me a little better idle.Mine idles at 900 rpm all day but this is just my opinion i've never tried a 950HP.I did mill the choke horn off my 750 for a little more air flow and jetted it 74/82 pv in back blocked off,hollow screws and 31 squirters,wont change pump cams till I get to the track,goodluck! graemlins/waving.gif

Isn't there a rule of thumb that says if you have couple inches of vacuum at WOT, the carb is probably a restriction and too small?

Yes there is that rule and I will install a vacuum guage in the car to let everyone know what the results are! graemlins/waving.gif

No vaccuum or less than 1/2 on the gauge at WOT 124 mph 5900 RPM with a bone stock 4781 double pumper with choke horn still on.

I installed a gauge in a gauge pod on the A pillar, just to check this, I was a little surprised, but it read zero or maybe upto 1/2

Mc71454,most people would have said you need a 950 to 1050 cfm for a 540.I don't have a problem with replacing something but I have to prove to myself I need it,I hate to waste money!It only took me 41 years to afford the car I always wanted! :D

Originally posted by JRS70LS5:
Mc71454,most people would have said you need a 950 to 1050 cfm for a 540.I don't have a problem with replacing something but I have to prove to myself I need it,I hate to waste money!It only took me 41 years to afford the car I always wanted! :D I hear ya, I thought for sure I was going to be pulling a few inches of vacuum but it didn't, so I bought something else :D

I intend on testing a carb Known to have a greater flow capacity than my 850. Box stock 850's typically 830 cfm +/- and the HP950's the same or maybe 840 cfm range.

I tested a 950 HP on my previous 468 and had no change in ET or MPH when compared to the same 850 I still run.

For my testing both with the vacuum gauge and the comparison of carbs I was surprised at the results, but heck that's what happened and I try to just call it as I see it. smile.gif

I agree with testing it yourself because certainly all vehicles will act differently. I am anxious to hear your results. Have a Good one.

i tried a 750vac sec, a 750dp, a 1050 domnator, and an 850 chokeless race carb on my 454. believe it or not all but the vac sec carb ran within .03 of each other. the 1050 ran a 7.32@94mph with a 1.61 60ft, the 750dp ran a 7.30@92mph with a 1.58 60ft, and the best overall idleing and driving and track tested carb was the 850, it ran a 7.29@93mph with a 1.58 60ft. the 850 was the only carb with annular boosters. it also was the only carb that i tried that had front and rear power valves. the 1050 was way too rich at idle with a stock HEI ignition, and sucked the fuel big time. the 750 never would idle right for me, it was an older one that did not have 4-corner idle circuit. but the 850 race carb was just right. ;)
HTH.