Thanks for all the info everyone! Think I will keep my eyes open for a deal on an RPM Air Gap. For the time being I will stick with the 3310, but if it's a pig I will save up more pennies.

The only problem with too large a carb on the street is that generally with an OOTB holley 4150 is you need roughly 20-ish % of rated airflow to initiate main metering, a good 650 will make more torque at part throttle and the transition will be less of a 'light switch' power-wise. A pro-form CNC replacement body on a 650-700 baseplate would be a nice upgrade. Plenty of 11 and 12 second cars run 650's, Really a 340 only needs about 600CFM of total airflow to turn 6200 RPM assuming 100% VE, the smallish .480 lift cam probably won't pull it much higher than that and it'll be past it's power peak sooner than that anyway (so the VE will be falling off). A smaller carb will also make a slightly loose converter a little better part throttle drivability too...opinions vary I guess but I've been running 340's on the street since at least the early 80's (including a 4 speed W2 headed 69 dart in 80-81).

The RPM and Air Gap are functionally identical, once the motor is warm (from the coolant flowing to it and around it and the crossover heat on the flanges) the manifolds both heat up about the same (IMHO) in normal summer driving. If it was a bracket car, I'd run the Air gap just so I could pack some ice under the plenum between rounds. t oput it another way...I wouldn't pass up a good deal on and RPM to hold out for an Air Gap on a street driven car.

John, this is Chris Johnson's old motor out of his Duster. It went 13 teens with a stick on street tires. I'm hoping with the 904 and good tires to go high 12's. I think that's reasonable.

B3, I looked last night and didn't see it. I was half asleep though.

The only problem with too large a carb on the street is that generally with an OOTB holley 4150 is you need roughly 20-ish % of rated airflow to initiate main metering, a good 650 will make more torque at part throttle and the transition will be less of a 'light switch' power-wise. A pro-form CNC replacement body on a 650-700 baseplate would be a nice upgrade. Plenty of 11 and 12 second cars run 650's, Really a 340 only needs about 600CFM of total airflow to turn 6200 RPM assuming 100% VE, the smallish .480 lift cam probably won't pull it much higher than that and it'll be past it's power peak sooner than that anyway (so the VE will be falling off). A smaller carb will also make a slightly loose converter a little better part throttle drivability too...opinions vary I guess but I've been running 340's on the street since at least the early 80's (including a 4 speed W2 headed 69 dart in 80-81).

The RPM and Air Gap are functionally identical, once the motor is warm (from the coolant flowing to it and around it and the crossover heat on the flanges) the manifolds both heat up about the same (IMHO) in normal summer driving. If it was a bracket car, I'd run the Air gap just so I could pack some ice under the plenum between rounds. t oput it another way...I wouldn't pass up a good deal on and RPM to hold out for an Air Gap on a street driven car.

Thanks!

My dad's 340 didn't pick up at all going from the OE #2100 iron intake to the LD340, it did pick up about .15 going to the Holley Strip Dominator, 4000 flash convertor though.

LD340.. overrated intake. People think it's the cat's ass cause the road race Challenger T/A & AAR Cuda used them.

I know EXACTLY what an LD340 is capable as I did flowbench testing on one, some porting and more testing, and then some more porting and more flowbench testing. It was all included in a post here 2-3 years ago. Gog-gone good intake with some work up to a certain point. There was still some on the table but I didn't want to do what was needed to grab it.

Flow #'s aren't everything. Just sayin..

You kill me. Ok I should have also stated that while flow testing I also test air-speeds (most guys won't or can't) and airspeed actually tells me more than the flow numbers do. Stick to your cast iron anchors as they will work too with proper knowledge. Carry-on.

Found it. Last page of second quarter engine parts( small block) section.
Poster named Rapid Robert has it listed

High 12's Shouldn't be a problem Dennis. Actually went with Chris when he originally bought that motor ( Thought it had aluminum heads on it at the time? Land yacht ran high 12.80 with a similar set up. Pic = modified 3310 I ran it the time.