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I've been looking into getting new heads because mine aren't doing very well and I also want more hp. My friend has an 80 camaro with a 305 in it and it has 350 heads on it and I was thinking about doing something like that. I was wondering if I get a pair of rebuilt 350 heads for my 305 if it would give me more hp than my stock heads. The other thing that I was concerned about was if 350 heads would fit on my 305. What size heads would fit on my 305,or is it pretty much all small block Chevy heads. I am planning on getting the heads off ebay. Any information or input would really help.
 

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Putting 350 heads on a 305 is going to drop your compression quite a bit. Id get a nice port and valve job on your current heads or look into some aftermarket heads for the 305.

Or you could take the money and instead, invest in a 350 and get more ponies out of that then you would doing any amount of work to those heads.
 

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Ive built a couple mild 305s that actually ran pretty strong, I think the 4 best choices are:
Vortec
L-98 vette aluminum
GM FastBurn

World Products S/R torquer 305s
I had L-98s on the 305 I built for my 86 Caballero....ran 13.70s with 3.08s
 

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What casting heads to you have? If they have 58cc combustion chambers and 1.84" intake valves then I'd keep them. Just clean up the ports under the valve seats and around the guides and you'd make noticeable gains throughout the RPM range. The Vortec heads I like, but can be a headache as they require a dedicated manifold, self aligning rockers and are limited to about .460" valve lift in unmodified form. They also need center bolt rocker covers. You want to keep your compression at around 9.5:1 and to do this you'll need the 58cc chambers. The Vortecs, being 64cc's will drop it under 9:1.
If you need to buy replacement heads then my pic would be the World SR 305 torquer heads. They're a bargain in my book.
They feature the following;
Bronze valve guides
Screw in studs
Hardened exhaust valve seats
3 angle valve job
Manley stainless steel valves
171cc intake runners
58cc combustion chambers
1.94" intake valves
are fully machined and have extra thick decks for crack resistance and also if further machining is required.
If you bought junkyard heads, then they'd cost you more than the SR's in the end if you were to have them updated to SR standard.
 

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I would leave the 305 heads on it, and buy an aftermarket cam, intake manifold and carbeurator. Doing these things will make more difference than using a set of 350 heads. The problem with the 350 heads is not only the drop in compression. The bore on a 350 is larger than a 305. I have heard that This means that if you use a set of 350 heads on a 305, the 305 bore will shroud the combustion chamber of the 350 head and cancel out pretty much all the gain you would have had with the better flow of the new heads. After you did the cam,intake,carb swap on your motor, If you wanted to go faster, just throw a 200 shot of nitrous on it, just kidding!!!haha. Sorry, no, but really, I would start buying parts for a 350 or 383 so that someday, you will have all the parts for one and then you would really have someting to work with. Has anyone else heard of the shrouding valve problem with the 350 head 305 cylinder situation.

Adam
 
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