Indy/rhs heads?

But this is where your missing the point, it's not the .500 max lift that your cam is but what is the flow under the curve? Is it better than the factory or equal or less, then you have to look at port volume CC's and what do both have as cast? If one has a larger port volume then obviously it should flow more at high lifts, but is your engine capiable of useing the additional port volume. If it's not then IMO your backing up. Because your engine is now over headed, and more than likely will suffer on TQ and HP at low RPM's. There is always trade off's in every engine, big ports = lot's of RPM's and must be cammed accordingly, just as small ports = low rpm performance and lot's of TQ. The thing is you have to get the best of both worlds, good TQ and HP and have a rpm range that the engine can live in. Most of the people that read these forums don't turn there engines over 6000 rpm's. And as in the case of the heads mentioned they are 179 cc's as cast with 2.02 intake valves. A 318 even over bored just doesn't have the CI to use the heads effectively, just as a 360 can't use them either. Now would they work better on the 360, sure they would as the CI is larger and is capable of useing a larger intake port runner. But even for the 360 they are large, thats why most 408 engines use the 171 cc Eddy's, and they work well in this application up to 6,000 rpm's.

I understand what your after with the head cracking problem of the factory heads. But I'm sure that the factroy heads are a good bit smaller than the 179 cc's of these. I have a set of factory magnum heads here and I'll cc the port runner tomorrow and post the size. I would bet that they are a good bit smaller than 179 cc's as cast. And in reality somewhere around 162 cc's I would bet.