Swirl Port heads

TheCraigMachine said

the 714's have heavier nail head exhaust valves, rotators on the exhaust valves, and the heads are factory machined for positive valve stem seals.

Click to expand...

I'm convinced that they are just a change over in numbers, possibly signifying what plant they were made in. Sometimes manufacturers will do that so they can help identify recalls, if and when they take place.

My 302 heads have the flat/ nail head valves with rotator retainers and short springs on the exhaust with positives on the guide seals.