They are better suited for a 302 but will work on the 347 well while producing good torque Ford used them on a 385 horse 351 and a 450 horse 392 crate. They are a good head and are made with good quality they are just not the hottest ticket out there. Are yours the the 303 or 305 version (58 or 64)cc. They will work well with that F cam and this will be a pretty driveable piece. The F cam likes nitrous!
They are the x303 version. Is that good or bad? How much hp will these add with the 347? One more question,....i ordered the a9l tto switch my car to mass air. Will it work as speed density with this set up?
That is a definate upgrade area in my opinion. If all else fails get a set of 24's out of a junkyard 460 truck motor and a 255 intank they are like 100 bucks. You will need the mass air upgrade for sure (camshaft) the x303 version is 58 cc that will give the motor a bit more comp. and will help in the seat of pants dept. n/a they will add about 40 horse but will shine when the nitrous is used