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If you were to buy a new set of heads that you were going to be using on a sbc 350 with flat top pistons what size runners would you pick if you wanted to end up with 500-550hp range? Then what cam would you use?

depends on where ya wanna be in your RPM range.

A good set of well built camel humps ported to about 170 - 180cc would be great for a street engine (Idle -6000) , alittle bigger is a set of 190-210cc that would make your HP number but would suffer at lower RPM for torque (1500-6500+) . A 64cc combustion chamber with those flat tops should get you around 9.8-1 compression and should run fine on pump gas (premium if at any real altitude 3000+)

As for cam, the Comp XE274 is an excellent choice for a semi streetable engine or the Magnum 280 would fit your bill. Fairly choppy or rough idle is what i would expect and the converter will need to be addressed for more stall as well

general guide line for your engine would be that you want around 224 to 236 @.050 duration - that will make the power but not give up too much bottom end.

Hope this helps a bit.

A.j.

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http://www.youtube.com/watch?v=ykgDNjeTa0g

what about using a set of 487 heads that have been fitted with 2.02/1.60 valves, milled down a ton (i dont know exaclty how much but they were milled for compression) with some port work and completely cleaned up. Also They have been guideplated changed to screw in studs and have bigger springs. Do you think these are capable of making 500 hp?

The 487 is a decent set of heads, the 2.02/1.60 work helps as well as the porting. The port volume is a little on the low side for the number you want. with a factory 161cc intake port, it could be opened up to make it work - but the large chamber (76cc stock) is gonna hurt you, even with the milling it just might provide enough compression to make the number - but with that much milling it gets dicey. Streetable target compression should be around 9.5-1 to 10.1. 10.5-1 if your good with tuning, have good octane gas, or aluminum heads.

an aftermarket head would be ideal, with 64cc chamber, 2.02/1.60 valves and a port volume of about 195-200ccs should easily make the number if the rest of the engines combo is well picked. you could probably get away with a well built stock head if you raise the compression, but as we know thats harder to do with todays fuel quality.

my .02 cents of thought anyways.

A.j.

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http://www.youtube.com/watch?v=ykgDNjeTa0g

I am probably just going to go with 487s since I had the work done to them and they are still sitting in the bags from the machine shop and ready to bolt on. The 500 hp mark isnt really all that important to me right now since the motor is probably going into my heavy truck street toy. Im probably selling the truck after I finish the paint work any way to make room for something about 2000 lbs lighter. Trying to make a 5000 lbs truck run the 1/4 fast isnt all that practical not to mention all the parts that will probably break under that load when it hooks hard.