Thread: carb size

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Hi, I would like to get some info on what some of you think I should use for a carb on a 400sbc.The engine has been bored .030 and is using hyperreutectic flat top pistons with a crane cam with 266lift & 444dur.Using stock heads and valves & springs.A high volume oil pump.A edelbrock eps intake.So I would like to know what do you think would be the best size carb.Probably will be using an edelbrock also.TKS for any opinions you can offer.

Originally posted by Larry 31
Hi, I would like to get some info on what some of you think I should use for a carb on a 400sbc.The engine has been bored .030 and is using hyperreutectic flat top pistons with a crane cam with 266lift & 444dur.Using stock heads and valves & springs.A high volume oil pump.A edelbrock eps intake.So I would like to know what do you think would be the best size carb.Probably will be using an edelbrock also.TKS for any opinions you can offer.

There have been a lot of different posts on carb size.I will assume you mean 444 lift and 266 duration.The cam close to those specs. has a power band of 2,000 to 5,000. In a 400 depending on where you have the cam installed you can take 300- to 400 off the power band.We can say you will be out of power by 5,000 or maybe a little more.I would go to www.Holley.com. and look under tech. and then under select a size.In my past experience you are better off going with a smaller carb if in doubt.I know some people will disagree with this.

I have a formula that will get you real close; take the engine size and multiply it by the intended rpm with that cam I'll say 5500 max and then divide it by 3456 then you'll get the cfm in this case 636cfm but a 600cfm would probably give you a little more low end. LOL

Originally posted by Red65Novawagon
I have a formula that will get you real close; take the engine size and multiply it by the intended rpm with that cam I'll say 5500 max and then divide it by 3456 then you'll get the cfm in this case 636cfm but a 600cfm would probably give you a little more low end. LOL

According to the Holley graph the 600 is the closest carb for the aplication.Just like you said.

That formula is the coolest!

Thanks for the info and sorry about the screw up on lift and dur.I'll pay more attention next time.I was thinking around 600 but wanted some more opinions.It's going into a 1931 chev. so top end is not a big deal just looking for a good cruising set up TKS again

try this link... http://www.csgnetwork.com/cfmcalc.html