I have a 400 small block bored 30 over in my 70 Chevelle with a 650 cfm 2 barrel carburetor. Would anyone know what the horsepower might be on this engine? Thanks for the help.

A 650 two-barrel?

What compression, what cam, what heads?

Dead stock, the highest HP was 265, in '70.

And don't forget, that 265 HP "rating" was using the exact same components that, a couple of years later, agfter they changed from "blue sky" methods to something that could be measured and has a relation to what the engine actually put out when in a car, went to 180 or thereabouts. So, if it's a bone-stock 70 400, it's "rated" at 265 HP, and you're actually getting about 180 HP out of it, and if you put it on a chassis dyno, you'll see around 140 HP.

I don't know of any 650 CFM 2-barrel carb ever being made. Biggest 2-barrel I'm aware of is a Holley 500, such as the familiar 4412.

As was said, in order to make even a remotely educated guess at what it's making, we'd need to know the heads, cam, compression, and exhaust; if it's not stock.

I don't know of any 650 CFM 2-barrel carb ever being made. Biggest 2-barrel I'm aware of is a Holley 500, such as the familiar 4412.


The 6425 2-bbl's are rated at 650 cfm. These are annular booster carbs discontinued several years ago. You can get modified versions of this carb up to 890 cfm. Here's one that sold on eBay recently

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33550&item=7916645313&rd=1&ssPageName=WDVW#ebayphotohosting

Sorry guys. It's a 4 barrel. I'm getting the compression, can and heads info and will post it as soon as I get it. Thanks- can you tell I'm new at this?

I stand corrected... that's one I've never run across.

Get more info, and no doubt you'll get lots of guesses.

180 horses... ouch

the great thing about those old 2-brl 400's was with a cam, intake, carb, and header swap your over 350hp to the flywheel and over 400lbs-ft too. obviously it isn't stock if it's .030 over. best way to learn is to ask questions. see if you can find out what cam, heads, intake, compression ratio, etc. anything and everything you can tell us about the engine and exhaust system.

I'm pretty sure that I will be able to track down all of this information but it might take some time. Thanks again for all of the help. I'll post the information when I get it.
Thanks

the 400 sbc bone stock was never intended as a high or even moderate performance type engine for that matter. it was designed to pull heavy sedans, station wagons and trucks around, run options like A/C, etc. they had very low compression and did not have competitive carbeuration, cam timing or head flow hitting the street. what they DO bring to the party is CUBES. therefore, all those other little hindrances are trivial to overcome and in my opinion presents one of the best opportunities for the true "hot rodder" to ply his hobby on. i have a 1970 400, what i should say is i have the block and crank from a 1970 400, virtually everything else in the engine is from elsewhere.

with a 400 it is easy to build compression with flattops or even dished pistons, unlike a smaller motor like a 327. I built a mild 406 awhile back for one of my friends with 462 camel hump heads, flattop pistons, 292 magnum cam, victor junior intake and holley VS 750. The thing had enough torque to leave in 3rd gear! power was all gone at 5500 rpms when the stock heads quit supplying enough air. ramble, ramble, ramble,