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I have a set of double hump (462) heads that were given to me awhile back. They were originally 1.94, but the guy who had them had the intake machine to 2.02. On another forum someone mentioned that since have the intake machined to 2.02 the heads would perform poorly is there any truth to this?
 

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Probably talking about unshrouding the intake valve from the combustion chamber wall. The larger valve will sit closer to the combustion chamber wall and as a result can hinder flow. GM cut the wall on the factory 2.02 heads to provide proper clearance. Most machine shops will do this for you, but not everyone does this. If you don't do it and install the larger valves, yes it can make a difference. If you look at an old set of factory 2.02 heads it's obvious where they opened up the wall a bit.
 

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when you de shroud the valve in the combustion chamber, that enlarges it obviously. but does it make a significant change in the CC size of the chamber? That being said, is it important to make sure that all chambers are same size after de shrouding all chambers?
 

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Please correct me, if I am wrong, but I have heard they are about 62cc's unless they are plunge cut to unshroud the 2.02 intake valve. Then they are 64 cc.

I say "about", because you really don't know, unless you cc them. Decking or "truing" the surface can change the chamber size, and I have heard that the chamber can vary some in size also.

If you cc them, do all 8 of them !

What engine are you using these on ? They really don't breathe very well. They only have about 155 cc intake ports. They were designed primarily for 327's under 350 HP ! If you put them on a bigger engine... they need to be "ported" to the max !

If those heads need more than $250 work, you can buy much better heads. Even the vortec heads made for street 350's have a 170cc intake port, and will easily outflow the old camel backs.
 

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I do this work all the time most heads 461 462 186 and so on are around 66cc i have never see a set that has been dead on at 64. When you do the chamber cut you will add about 1 cc. You all so need to do the bowl cut for the 1.600 and 2.02 valve.
 

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What engine are you using these on ? They really don't breathe very well. They only have about 155 cc intake ports. They were designed primarily for 327's under 350 HP ! If you put them on a bigger engine... they need to be "ported" to the max !

If those heads need more than $250 work, you can buy much better heads. Even the vortec heads made for street 350's have a 170cc intake port, and will easily outflow the old camel backs.
I'm putting the on a 66" 327, I don't think I'm going over 350 hp, because of my current setup. I plan on using my original 2 speed powerglide and I have 3:08 gears.
Btw where can I get better heads for 250?

oh yea, Thanks mike for the pic.
 

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Tom to answer your question flat milling a 23 degree SBC head .006" results approximately in 1cc reduction to the chamber. You can usually flat mill .030 before you run into needing to start cutting the intake. The .030 = -5 cc. Again these are approximate numbers listed in several publications. Only way to know for sure is to measure them.

Also guys when I had my old 461s that I used on a 331 small block cut for the 2.02 and 1.60 valves they ended up at 66 cc, but I had flat milled the heads to true them up also, so I lost a little bit of volume there. Most 461, 462s were 160 cc I believe.
 

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I'm really not sure, what the actual dollar amount is that they are not worth any more work is, but some would say $100 ! A different set of heads would actually cost about $600.00 on up. You can probably pick up a set of used vortec's for much less, but then you would need a vortec intake and center bolt valve covers. I have a set of 461's on my car with stainless valves etc. I don't think that I could sell them for $300 ! I have seen numbers that say 150 to 160 cc on the intake ports, what they actually check out at ? I don't know.

 

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I'm really not sure, what the actual dollar amount is that they are not worth any more work is, but some would say $100 ! A different set of heads would actually cost about $600.00 on up. You can probably pick up a set of used vortec's for much less, but then you would need a vortec intake and center bolt valve covers. I have a set of 461's on my car with stainless valves etc. I don't think that I could sell them for $300 ! I have seen numbers that say 150 to 160 cc on the intake ports, what they actually check out at ? I don't know.

Why are you so against camelhumps if you have them on your engine:confused:? By the way what kind of E.T's do you get in the 1/4 mile with your set-up?
 
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