Heres acouple of questions i got.... I'm going to probly have a 400HP(+-)460BBF. I'm thinking of a Edelbrock Performer, or Steath Intake. I dont plan on anything over 5000rpm. What is a good CFM? 600,650,700,750? I would like the best fuel economy and performance. And what about Secondary's? Mechanical or Vacuum? Why? I under stand how the secondarys work i just want to know why you perfer either.I'm so confused on this issue......Almost forgot, has anybody run one of those PREDATOR Carbs?
[ August 18, 2002, 07:25 PM: Message edited by: AntRant ]
go with the stealth over the performer.As for carbueration a 750 will do the job a mech is better since you can adjust the secondary jetting.the vac secondary you need to get a few parts to make it work(metering block for rear,spring kit).I myself run a vac secondary carb(holley 3310)but have changed out the rear block and did the spring and it is pretty responsive and when wide open is doing the same job as the dp.I am also running a nitrous unit also.
Hey Ant, I'm using a 715 Vac Secondary on a 10:1 468 at 53-5400 rpm's....With the Stealth.
Its plenty of carb!
I had to try my nice big 850 DP...it did nothing for the motor! Its sitting on my bench waiting for MUCH more motor, with MANY more rpm's. (I'll sell it to ya)!!!
[ August 18, 2002, 07:27 PM: Message edited by: HammerDown ]
I would lean towards the stealth also, I run an RPM performer. I would however run an 850 mechanical.
Now is the Steath any taller than the Torker I? I have limited space on my CVX20.
On a Edelbrock i have i noticed the vacuum secondary use what looks like a counter wheight for the secondarys. now as you hit a wake or if you trottle from 1500 to WOT is it possable for the butterfly the rock open and close or does the vacuum hold it?
AntRant:
On a Edelbrock i have i noticed the vacuum secondary use what looks like a counter wheight for the secondarys. now as you hit a wake or if you trottle from 1500 to WOT is it possable for the butterfly the rock open and close or does the vacuum hold it?Answer to that is no! It will not move on you.
As for CFM requirements for your engines Horsepower? 1.2cfm per Horsepower is all the cfm your motor will use whether it is 1050 Dominator or 650 Double pumper. So 480cfm is the only amount of air your 400HP motor will pull with that at 5500RPM. When you talk about Holley's advertised cfm ratings, 650, 750, 850 etc; these are catorgories for the venturies and the vacuum signal they respond to, people tend to be mislead into their actual meanings.
For your motor:
A 650 is going to be better off the line and stronger within the lower RPM band.
A 750 is a great choice for upper RPM conditions with little of a sacrafice on the lower end, no big deal with your cubic inches.
The 850 would hurt you alot down low but would be great for the 6K band, but your motor starts to drop off on the horsepower at 5000RPM (dependant on cam specs).
See who gives a shit if a carb flows 750 (advertised cfm) and some speciality shop said it flows 20cfm more with some special trick. They are only changing the vacuum signal, which pulls more or less fuel for your fuel requirements at any given RPM. NASCAR uses 390cfm carbs that flow 750cfm at 7000RPM with 500HP...How is that? Because your motor determines the cfm it wants, not you. But the vacuum signal of a 390 carb is so much different, that at 7000RPM it is sucking fuel like you wouldn't know! I mean guzzling! But the body is only 390cfm....So what! The motor is 500HP and its determining the cfm is wants. That's just physics!
Hope I haven't confused anyone.
Stick with the 750...it is a great move if your consider to move into more horsepower and higher RPMs over-time, for Marine use.
Give us a call if your interested in having one custom built by TPC Racing.
Hammerdowh, how much?
HOSS:
Hammerdowh, how much?Cost?
This all depends on what your needs are and what you want? I offer Anodized Billet aluminum baseplates, severe duty parts, Chrome, polished main bodie venturies, Race Banjo style boosters....I need more info than just a horsepower rating and motor size. On my website there is a form that you fill out so I can determine what will work best for you.
Overall 4779 Double pumpers start at $499 Stock Custom assembled and blueprinted w/ free color choices and can climb up to over a thousand trimmed in all Billet aluminum, Chrome bowls, Marine J-tubes, sealed throttle shafts, HP bodies with adjustable air-bleeds....List goes on. The average 750cfm Double pumper can be close to $600.00.
You can also send in your used Holley carburetor to be reconditioned/overhauled to brand new, with the sames options at a smaller price as well.
It's best to give me a call so I can work a price to suit your needs and wants.
-Ty (877) TPC-CARB
Hotcrusader76, I'm still a little confused about CFM. If Nascar uses the 390cfm how does it flow 750? Wouldnt 390cfm mean 390cfm?I thought that the advertised CFM meant what the carb would flow of air. Or does it represent somthing else? Can you explain "vacuum signal" then maybe ill get it.
Posting Permissions
Reply With Quote