Ford Repair: performance package, mustang 289, gross valve

Question
Hi Steve.
I have a 65 mustang 289 it has a performance RPM fuel intake and a 600cfm carburator an I just put an new cam with new lifters the cam specs are:
* Advertised duration: 292 intake/302 exhaust
* Duration at .050 in. cam lift: 234 intake/244 exhaust
* Gross valve lift: .520 in. intake/.544 in. exhaust
* Lobe separation: 114 degrees
* RPM range: 3,400 to 6,800
when I start the engine it sounds really bad, especially somewhere arround the timming chain(it is stock) and in hi rpm the heads sound bad too. well i thought that it must be because the cam have to much lobe for the valve springs,but i don't know why the timming chain. Could you advice me wich timming chain, and cylinder heads will fit correcly to perform bettter.
Thanks very much.
Rodrigo  

Answer
Rodrigo-

  I can see two problems here.  One, as you mentioned, is that the valve springs you've got probably aren't up to such a big cam and are binding.  The second is piston-to-valve clearence.  Unless you flycut the pistons, with that much duration and lift I wouldn't be at all suprised if there's piston-to-valve issues.  Cams are a good example of how bigger isn't always better.  I'd go for a cam with a duration in the 220-225 degree neighborhood...maybe a little more in the exhaust side.  And keep lift around .500 in. or so.  This will give you much better throttle response and vacuum.  If this car is a mostly strip car, however, then simply flycut the pistons since the bigger cam will give you better top-end power.  It's all about what you want from your car.  Hope this helps.

Steve