What carb to run

[Craft86MJ]

hi, I got a 2.8 v6 and I'm looking to purchase the Edelbrock intake manifold, but don't know what carb to purchase. Should I run the factory or the 390 Holly? I've even seen some people run a 500. I'm looking for the most reliable option. Thanks

[Eagle]

500 cfm is too much for a 2.8L engine. If you do the math, you'll see that a 2.8L engine at 5,000 RPM is pumping only 246 CFM. The 390 will be MORE than enough.

[86FUBAR]

you could also get the weber carb kit as its a bolt on installation to the factory manifold . that would save you some time and money as you wouldnt have to purchas a new intake and install , though it wouldnt be a 4v carb i don't think it would matter much

[Craft86MJ]

500 cfm is too much for a 2.8L engine. If you do the math, you'll see that a 2.8L engine at 5,000 RPM is pumping only 246 CFM. The 390 will be MORE than enough.

 

How does one do this math, for future reference?

[Eagle]

500 cfm is too much for a 2.8L engine. If you do the math, you'll see that a 2.8L engine at 5,000 RPM is pumping only 246 CFM. The 390 will be MORE than enough.

 

How does one do this math, for future reference?

 

1. Convert engine size in liters to cubic inches [1 liter = 61 cubic inches), then convert cubic inches to cubic feet.

 

2. Divide by two, because it's a 4-stroke engine. For each revolution, only half the cylinders are on intake, the others are on exhaust.

 

3. That's how much air (approximately, depending on the cam) is pumped through the engine per revolution. Multiply by the maximum RPM. I used 5000 RPM because that's typically where AMC/Jeep always set their redline.

[Craft86MJ]

Thank you!