350 heads for 305

Seen people talk about putting 350 heads on a 305 for max efficiency... does this actually effect/improve the combustion/flow/power?
Are the heads the same physical size?
Thanks, GC
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No it actually does just the opposite. The combustion chambers on 305 heads are 52 or 56 cc depending on year. The combustion chambers on 350 heads are 64 or 76 cc depending on year. All you'd be effectively doing would be lowing the compression ratio from 8.5 or so down to 7.5 or so.
Yeah, 350 heads flow alot better as the 305 heads have teensy valves, BUT if the compression ain't there it doesn't matter anyhow.
Doc
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Thanks Doc... I'll just leave it be, and maybe look for headers/dual exhaust as the only option for a slight performance increase. With gas prices, the 305 does quite well, now that I finally got all the "kinks" ('86 Silverado) out of the system. Thanks for the very useful info!
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You`d have to do lots of upgrades to save money on gas with the 305.My stock 350 was great on fuel.
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would have to get different pistons to take up the added volume
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For all the work involved, you'd be better off grabbing a complete 350 and blowing that instead of swapping heads, etc. A blown 305 with stock pistons and bottom end with stock 350 heads would still be putting out under 300 HP.
Doc
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i agree (as usual ) with Doc.... 350 heads on a 305 would lower the CR to a blower friendly level where overdriven pulleys could be used to make plenty of low-end grunt.....but the cast pistons in the stock block would fail quickly with the added cylinder pressures
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Mad-Dog
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Ditch the 305 junk and rebuild the 350...or just buy new GM-G!

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