974 vs 915 heads

[torredcuda]

I have a 76 360 with 974 heads,wondering if there is any advantage to bolting on a set of 915 heads.My Mopar smallblock book says they are the same 65cc chambers and the same 1.88/1.60 valves?

[moper]

Apples to apples, meaning used heads for used heads, there is no difference you'll notice. If one set is new and fresh done by a good shop, then you'll have better results. Same basic heads.

[torredcuda]

That`s what I figured.

[moparnut]

you'd be better off getting a set of 202 J heads

[Chryco Psycho]

The 915 heads are the J heads

[moparnut]

my point was there are 2 different J heads, ones that are 188 intake(which will gain you nothing) or the 202 j heads which will let your motor breathe much better and increase HP

[71chally416]

I'd rather start with 1.88 heads than 2.02 heads, especially if the 2.02 heads have already been worked on. Then when you install the bigger valves and do your VJ you can have the highest possible seats and the best possible port flow. If a valve is sunk .050" into the chamber to try to correct seat runout then that's .050" off your effective cam lift. Your .450" lift cam now has .400".  I've seen many sunk worse than that.

That being said, there isn't a whole lot of difference in the later SB heads. Some have a nice thermactor boss lump in the floor of the exhaust that actually helps flow on the flow bench, but otherwise they have the same flow potential as the earlier 2.02 heads.