Dunecune442

Hey all, im in the market for a new carb for my 442. Here are the specs...

its an original 1970 455 rocket bored 30 over
stock internals
stock heads
headers/exhaust

Now I would like to know how big of a carb to get since the 'ol rochester shit out. Im thinking around 850cfm would be nice. I am putting new inernals later this year, and may do some head work and I need a carb that I can use now and after the buildup. Compression is stock, and I dont think Ill bump it above 10:1 (Im thinking of supercharging it. Has anyone been blessed enough to see a supercharged bigblock? What kind of numbers was it laying at the wheels?

Also, I need an aluminum radiator (the bigger the better) for the 442. The stock GM core sucks (i have a new OEM one and it still runs alittle warm).

Finally a good local shop I can buy this from. I only know of blue coral but Id rather a shop that specializes with GM parts. Would it be better to order offline?

Thanks for your help all, this project is going to be done shortly!

F*r*a*n*k*e*i

Carburetor Size (Street and Strip):

Street Carb cfm = (max rpm x displacement x 0.85) / 3456
Race Carb cfm = (max rpm x displacement x 1.1) / 3456

That'll get you your ideal CFM size. Jetting will depend on your compression, timing, and cam. Depends on your gearing, cam, and transmission on if you want vacuum or mechanical secondaries, etc...

I've got a 650cfm Edelbrock Performer with vacuum secondaries on my 350. On my 383, I've got a 750cfm (although oversized) Street Demon with mechanical secondaries.

Dunecune442

How do you like the street demon? Are they a bitch to tune? How do they keep their tune compared to edelbrock. The main reason Im a little against buying a holley product is the horror stories. How is the setup treating you so far Frank?

Thanks for the speedy reply. I still cant find a good olds website (442.com is very basic and has some old articles with no real buildups), so info is hard to come by. Lucky chevy owners...

Oh, and what kind of secondaries do you recommend? The ones on my quadrajet are essentialy fused, they refuse to open AT ALL. I need something that can take some abuse, and not really have to worry too much.

F*r*a*n*k*e*i

I've never ran the 383, so I can't tell you. In fact, all the 383 is now is a rotating assembly in the block, I'm still waiting to buy my cam. I got the carb though!

The Edelbrock is pretty shitty, but it's a refurb, so I wouldn't take my opinion too hard. It's flaky about holding idle, sometimes it sticks, etc...

Manual tranny with short gears in the back love mechanical secondaries. Automatic with normal or tall gears in back, go vacuum. Of course there are exceptions like cars with autos and sick ass converters.

TampaMCS

I just had to drop from a 750 vac sec to a 600 double pump...Night and day for my stang...

Warm 302, 2400 stall aod and 3.80 rear gears. The 750 caused a bog like there was no tomorrow...

HerHotRod

I put a Griffin in mine and it was night and day diference. I measured the size of what I already had, best matched it to what Griffin offered and then went to Gearhead and had them order it. They had it on the next truck . I did have to add a tranny cooler since the new radiator did not have a connection for the tranny lines.

74javelin

my friend just got done building a 57 chevy nomad drag car for a guy. 454 with a nice cam and heads around 800hp. the owner put a 950 carb on it. but my friend thinks a 750 would work best. they run a 600 holley on there 350 that runs 6.30's at sunshine. but they are chevy engines.

for some odd reason amc likes big carb's. you can put a 750 holley on a stock amc 360 and get better 1/4 times over a 600 carb i don't know about's old's


ps: i'm only putting a 750 on the motor in my sig. it's a 401 ci

Dunecune442

yea the olds seems alittle hard to figure out. Basic feel Ive gotten is that 850 is perfect up to about 650 hp, after that you have to re-jet or get a bigger carb period. Ive been trying to get some info but all the Olds buildups are about 6-7 years old. Not a very popular/common motor I guess...