What 4-barrel carburetor

[Ddhotbot]

I have a 318 engine with a 2 Barrel on it I would like to swap it out to a 4-barrel I have a cast iron intake. What 4 barrel carb would be best

[randy73]

I like edelbrock, but a lot of people like Holley.

I would recommend you use Holley's carb calculator to make sure you do not get a car to big.

[ACUDANUT]

I like edelbrock, but a lot of people like Holley.

I would recommend you use Holley's carb calculator to make sure you do not get a car to big.

I agree. Find a Holley, but not a car too big.
Holley 650 should work perfect.

[c00nhunterjoe]

On the stock cast 2 barrel intake, i would leave the stock 2 barrel carb. This is no noticable gain running an adapter to a 4 barrel.

[randy73]

I like edelbrock, but a lot of people like Holley.

I would recommend you use Holley's carb calculator to make sure you do not get a car to big.

I agree. Find a Holley, but not a car too big.
Holley 650 should work perfect.

650, on a stock 318   

[randy73]

On the stock cast 2 barrel intake, i would leave the stock 2 barrel carb. This is no noticable gain running an adapter to a 4 barrel.

Is it because the adapter would create a choke point, i.e. A/F restriction or ?

[PRH]

On the stock cast 2 barrel intake, i would leave the stock 2 barrel carb. This is no noticable gain running an adapter to a 4 barrel.

I would say the next step up the food chain for a cheap upgrade to 318 with the stock 2bbl induction is a 360 2bbl intake and carb.
There will be a mismatch on the port openings, but it still makes more upper end power over the 318 set up.

The better, although more expensive option is a std performer and small 4bbl carb.

The 360 2bbl cam(Clevite 229-1663)is also a nice hp upgrade in a stock 318 to go along with the induction upgrades.

[John_Kunkel]

I have a cast iron intake. What 4 barrel carb would be best

You'll probably find that most aftermarket carbs won't fit a factory iron manifold without the use of a spacer to clear the linkage. For a stock 318, 500 cfm Edelbrock is sufficient.

[Ddhotbot]

I am installing a factory cast iron 4 Barrel manifold probably off of 360 I am not putting a 4-barrel carburetor on a 2 Barrel manifold I am changing manifold and carb what 4-barrel Number

263091803572 eBay #

came stock on these cars

[PRH]

I am installing a factory cast iron 4 Barrel manifold probably off of 360 I am not putting a 4-barrel carburetor on a 2 Barrel manifold I am changing manifold and carb what 4-barrel Number

263091803572 eBay #

came stock on these cars

Afaik, 360's with 4bbl's all used spread bore carbs.......so you won't be able to buy a "new" carb to fit a 360-4bbl manifold.
Adapter plates are available, or remaned TQ's and Q-jets.
A 1970 340 was probably the last production SB motor to use a square flange 4bbl manifold.

[sccachallenger]

I am installing a factory cast iron 4 Barrel manifold probably off of 360 I am not putting a 4-barrel carburetor on a 2 Barrel manifold I am changing manifold and carb what 4-barrel Number

263091803572 eBay #

came stock on these cars

Afaik, 360's with 4bbl's all used spread bore carbs.......so you won't be able to buy a "new" carb to fit a 360-4bbl manifold.
Adapter plates are available, or remaned TQ's and Q-jets.
A 1970 340 was probably the last production SB motor to use a square flange 4bbl manifold.

Take a look at the newish Street Demon carb. Sort of looks like a Thermoquad. I believe the base plate is drilled for both bolt patterns, and comes in a 625CFM size.
Like to hear from anyone who's using one.

[PRH]

Take a look at the newish Street Demon carb. Sort of looks like a Thermoquad. I believe the base plate is drilled for both bolt patterns, and comes in a 625CFM size.

There's more to being compatible with a spread bore manifold than having the correct bolt pattern.

I've never seen one of those carbs upside down, but unless the throttle blades are similarly sized and spaced, like the TQ........then you'll have a hard time opening them with it bolted down.

I guess what I'm saying is.......if those carbs fit right on a std square flange manifold with no issues with the throttle blade operation.......it's not likely it will work on an oe spread bore manifold.
At least, not without some modification to the manifold.

Like I said......I haven't seen one upside down.......so I'm just trying to visualize how the intake and carb would interface.

[Wicked72]

Find something thats about 500cfm with vacuum secondaries. Your engine can only flow so much so getting close to that matched flow will give you great throttle response and the vacuum secondaries with only kick in when the engine actually needs the extra air. Will make for a very nice setup.