91bigredgt

i decided to build this 408 to use a carb instead of the efi (cheaper)
so far im going to purchasing
victor jr heads
victor jr intake manifold
jay allen cam (doing roller conversion)
bbk long tube headers
slp exhaust
h pipe
electric water pump
msd box

I really need help picking out a carb though cause i dont have nearly the experience with carbs that i do with efi but im tryin to learn. Im tryin go with something that can handle 450-500hp maybe alittle spray and that can be driven on the track as well as the street. Not sure whether i want an electric choke or manual whatever would be best in my situation. Also I need to know how i would need to set up my fuel system also.

my77stang

you want a 750, something holley based - barry grant, holley, or if you want a REAL carb get a proform.... you wont be sorry.

if you want all out power you want something that has mechanical secondaries (a.k.a. double pumper) but if your going to be driving this thing around everyday you would be better served to get something with vacuum secondaries.

electric choke > manual choke if your going for streetable, for all out power you want something that doesnt have a choke tower anyways.

btw, crane ignition > msd. i currently have msd stuff but my next ignition system will be a crane setup (if that tells you anything)

if it were me, i would make my choice betweem the following two based on what my driving habits with the vehicle will be and how much i wanna spend in gas everytime i turn the key [8D]

proform 750 double pumper with no choke tower


proform 750 vacuum secondaries with electric choke

rust_stang

A 850 or something closer to 900cfm.

my77stang

overcarbing FTMFL (and it happens SO often)

you dont need to go crazy with the cfm size, you need to actually dial the carb in once its on the car. this means different jets, different accelerator pump cams, different size discharge nozzles, and different air bleeds (only proform or other very high end carbs offer air bleed tuning and its a feature you WANT to have).

rust_stang

Fine dont listen to me. thats around what carb you need to go faster though. i put a 750dp on my stock 351 and all it did improve my 1/4 time and top end by alot.

91bigredgt

my biggest concern is that i dont wanna go to small and end up having to buy another one or vice versa with getting something to big and not being able to deal with it on the street or it just being to much for the motor

my77stang

its simple mathmatics.

a 408 cubic inch motor @ 6500 RPM's with 95% VE (you'll be 90-95% if everything is matched very very well, stock motors are 80-85% VE) anyways that equals 729 CFM. round up to 750 and theres your answer

not to mention your motor doesnt sit @ 6500 even when your romping on it your only going to see those higher rpms very briefly while getting ready to shift into the next gear.

worth mention, is that when using a dual plane intake you can get away with running a slightly larger carb, but your looking at a single plane intake so sticking to the formula FTW.

rust...... all i can say is LOL @ your last post

91bigredgt

lol thanks man yeah im not tryin to build an all drag car or anything just something i can drive and know i can basically thrash anything that challenges me (not on the street of course) lol thank guys

WhiteWindsor

If your looking for something mainly for street driving and you will be driving it often, then as 77 says go with a 750 with mech. sec. With a lot of street use i would also get a electric choke. I have a 357 with the HP Holley 750 and no choke tower, but i rarely drive mine.

rust_stang

well i guess i know how to tune engines to adapt and you haven't quite figured that out yet..