head work
#1
head work
so im stickin with the SB chevy, no BB for me. Question is, when i pull the motor, im gona stroke to a 383, and possibly bore it .40 over... two questions arise here...
Any head work necessary? i want to buy vortec heads for it.
What CID is it after the stroke and bore? thats just a curiosity thing more than an important thing.
Any head work necessary? i want to buy vortec heads for it.
What CID is it after the stroke and bore? thats just a curiosity thing more than an important thing.
#4
RE: head work
384.6 for 4.04 bore 3.75 stroke. The vortec heads are good flowing heads stock I dont think its worth going to crazy porting them with the exception of maybe a little on the exhaust side from what Ive seen in flow # there isnt alot to gain on the intake and you take a chance of making them worse. I dont even think it would be worth changing the valve size in them either. The heads in stock form will bury a set of camel hump heads the vortec intake sidewill flow in the 230 cfm range at .500 lift but dont gain a whole lot after that. The problem with the vortec in stock form is the valve seal /retainer clearance. the rule of thumb is .060" clearance beyond the measured clearance meaning if you had a measured clearance of .520 you would subtract .060 for your safe cam lift of .460(this is the actual measurement of the vortec I just put together) I did a bad thing and just ground down the retainers .010 for the required .470 cam lift I am running the real fix is to have the valve guide machined down for clearance. For the .470 lift I am running I was able to get a set of stock car stock diameter springs with enough seat pressure if you need more you have to machine out the spring pockets for larger diameter springs. Some of the aftermarket vortecs already have this corrected. If you are going to the junkyard to get a set of vortecs (I paid $200) there is two casting numbers 906 and 061 some of the 906 heads have a special hardened exhaust seat it was believed that this hindered flow my machinest says no but I dont believe they have the same three angle valve job as the 061. More than you ever wanted to know about the vortec heads lol. I assume you know the take a specific intake also i had some trouble port matching them due to the angle they go together but I think unless you are going for every last bit as long as your intake is only slighly smaller than the head and not the other way around you will be fine.
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