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looking at maybe building a pair of these up. ported etc. what all mod's need done and how much power could one make out of a 355 with the right cam intake combo. we are thinking of a hollet street dominator dual plane(so far its the best all round intake i have used) and still up in the air on the cam. about 10.1 to 1 and it will see some spray. looking into better heads and wondering if it worth doing these up or buyying aluminum.
My understanding on the Vortec heads is that they are somewhat limited to their RPM range... Before I stuck a bunch of money in them, I would seriously consider some aftermarket heads. If you don't want to part with the extra bucks for aluminum and weight is not an issue there are a number of companies making some hi-quality cast heads.
Mine always cost a bit, but I have a long chat with the guy or company doing the heads and buy them with the CNC porting and flow bench work all done. Yeah, you can do the porting at home, but without a flow bench it's just a lot of guess work.. I know that 5 axis mill is a whole lot more accurate then a hand held porting tool and a pair of calipers........
If you have your mind made up on a set of Vortec heads . The Best ones to buy are the RHS Vortec Pro Torker heads . They have 2.02in / 1.60ex valves and Flow 27cfm more then GM #906 Vortec heads do . And with the springs and retainers they use . You can run a camshaft up to 525 Lift . Also you can run early or Vortec intake manifolds on the RHS Vortecs . You can buy them ready to run . Part # RHS12410K1 from www.competitionproducts.com As for the best Dual Plane intake Go with the Weiand Air Strike # 8501 with a 700 CFM Holley D/P . And for a Camshaft the Comp Cams XE268H . That camshaft is 224/230 dur at .050 and 477/480 Lift and has a 110 L/S . With these parts on a 355 with 0 Deck Flat Top pistons 10.1 you will have 415 HP at 5700 and 423 ft lbs at 4000 .
Gearhead
I'm certainly no expert on these heads, but be careful if you buy a set of used Vortecs.
I have had 3 of them checked and they have all been cracked.:mad: The machine shop tells me they are very prone to cracking in the valve seats when they get hot. Be sure to get a return guarantee from the seller.
I'm about ready to go in another direction. Pretty soon I'll have enough in gas and inspection fees to pay for a new set of heads!
Mike
I agree after market heads are better and cheap. You could even find them cheaper if you buy used.Quote:
Originally Posted by Dave Severson