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Old November 2nd, 2006, 12:10 AM   #1
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Default 305 heads on a 350 why

friends car has a 350 4 bolt main with 305 centerbolt heads is it a good thing or a bad thing any reason for doing this as far as performance
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Old November 2nd, 2006, 04:08 AM   #2
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Low end torque would be about the only benifit of 305 heads. They have a smaller combustion chamber that'll bump up compression, but won't flow with a crap over 3500 rpm.
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Old November 2nd, 2006, 12:58 PM   #3
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When I built my engine for my monte carlo, I used the old 305 ho heads that where 58cc chambers and built a 350 flat top bottom end with those heads aluminum intake and a 600 holley.. It woke up the 350..
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Old November 2nd, 2006, 11:34 PM   #4
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so it better for torque at low rpms and thats about it
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Old November 3rd, 2006, 03:34 AM   #5
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so it better for torque at low rpms and thats about it
Pretty much. It's a great set up for a low budget truck engine for towing or off-roading. Not so good for something you want to knock down fast 1/4 miles times.
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Old November 3rd, 2006, 04:43 PM   #6
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The 305 H.O. heads....dont they have the bigger valves with the smaller combustion chamber?
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Old November 3rd, 2006, 05:07 PM   #7
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If I remember right the standard 305 valves are 1.84" and the H.O. are 1.98. huge difference? I don't think so. the best heads out are the Dart or merlins. they are bolt on HP in my book, I wouldn't build a chevy engine without a set. stock heads more trouble then they're worth.
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Old November 3rd, 2006, 05:20 PM   #8
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If I remember right the standard 305 valves are 1.84" and the H.O. are 1.98. huge difference? I don't think so. the best heads out are the Dart or merlins. they are bolt on HP in my book, I wouldn't build a chevy engine without a set. stock heads more trouble then they're worth.
The basic 305 head intake size is 1.74, the "H.O." was 1.84.
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Old November 3rd, 2006, 05:31 PM   #9
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The basic 305 head intake size is 1.74, the "H.O." was 1.84.
I'm sorry if that .10 of an inch cost you .100 of a HP!




so I can't remember every number in the order I read it 20 years ago. :miff:
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Old November 3rd, 2006, 07:38 PM   #10
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I'm sorry if that .10 of an inch cost you .100 of a HP!




so I can't remember every number in the order I read it 20 years ago. :miff:
Just clearing up the info
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Old November 5th, 2006, 09:10 AM   #11
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so it wouldnt be a bad motor for my truck i have it know and took the heads off it was leaking put knew gaskets in it at least its a 350 4 bolt main bored .30 70s block with newer 305 heads but i have aset of newer 350 heads from my motor which would be better i have a 90 k2500 with 465 trans and its fuel injected my motor threw 2 rods in cause your wondering
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Old November 30th, 2006, 10:07 PM   #12
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i just did this in my jeep it pull like crazy with 39 iroks im running an sm465 and im tbi running little rich
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Old December 1st, 2006, 12:14 AM   #13
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If your going to pull the heads go after market heads and get the 202 exhaust valves in it . The larger the valve the better they breath . I dont have issues with stock heads . Have a machine shop suggest a head design for that motor and put a set of larger valves in it . More then likely they will need a valve job any way . After market is the best way to go as yetti said IF you have the cash to burn .
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Old December 1st, 2006, 10:24 PM   #14
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you gain compression. If you want bottomend and dont care to rev it will be fine. If im not mistaken it will be going from 76 to 58cc chambers. if it were me and i had money i would put a set of world products s/r heads 1.94/1.50s
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Old December 2nd, 2006, 10:55 AM   #15
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thanks guys i took my 350 heads in to get done today they are going to change the valves and everything a friend of mine is doing it he came and looked at my motor and we figured everything out he works at a machine shop
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