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Which heads?

C

CHEVYDADDY

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ok i had 85 k5 blazer 305 4 speed but ran it dry of oil.(d**m) or did i just want a new motor?... well yes new motor but no not this way but get this traded riding lawn mower for 350 0.40 over short block good to go. heads to match. bot i only hurt my 305 lower block haeds are fine! so.... 350 0.40 over with 350 heads or go with 350 0.40 with 305 heads.i have to clean all this up short block and heads (both set) any hint what to use very little surface rust but there is some.
 
CHEVYDADDY said:
ok explain i have hread it alot said more low end?
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Tiny valves and intake runners, they're meant for a 305 cubic inch engine.

Of course they will work but it will choke a 350. Pretty much any 350 heads will be a drastic improvement over 305 heads on a 350.
 
CHEVYDADDY said:
ok i get what you are saying but why do they say it will create more low end?
305 head??
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Well, usually smaller valves and smaller intake runners mean higher intake velocity at low RPM's and, if the cam is matched to the heads and motor, more low RPM torque.

But putting 305 heads on a 350 does not work well. I tried giving away my 882 casting (350) heads for a long time, they ended up going to the recycler. 350 heads are easy to find and they're cheap.
 
Ummm alot of guys run 305 heads on 350s. I wouldnt recommend it for a truck but as far as building a budget motor the 416 casting 305 HO heads with some at home port and polishing and bigger valves are 350+ hp performers.
 
ok you got me at cam matches heads and motor i have the heads (350) that go with the motor so i believe i will go that route.



but any one else????
 
vortec heads! but get the 2.02 intake instead of the 1.94 intake if u can the 2.02 heads allow for more lift and also correct me if im wrong but i believe they flow better then the 1.94 from port design. u have to get a vortec style intake manifold if u get vortec heads also.
 
vortecs are your best bang for the buck I agree. no need for any fancy upgrading. You'll hit 300hp with a mild lift cam no problem. Honestly how much more do you need?
 
If you put 305 heads (58cc chambers) on a 350 (85 350 heads have 76cc chambers) you will end up with way too high of a compression ratio and the engine will ping severely. The difference is about 2 point of compression, so if you started with 9:1 you'll end up with 11:1.
 
4X4HIGH said:
If you put 305 heads (58cc chambers) on a 350 (85 350 heads have 76cc chambers) you will end up with way too high of a compression ratio and the engine will ping severely. The difference is about 2 point of compression, so if you started with 9:1 you'll end up with 11:1.
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werent there 64cc 305 heads? or am i thinking something totally different?
 
i did the 305 heads on a 350 thing once in my younger days, bad, bad idea! would ping with 93 in the tank and ran worse then it did with the cracked 350 smog heads on it. i think 4x4HIGH is right about the 58cc never seen a 305 head with anything different
 
38377k5 said:
Tiny valves and intake runners, they're meant for a 305 cubic inch engine.

Of course they will work but it will choke a 350. Pretty much any 350 heads will be a drastic improvement over 305 heads on a 350.
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**** when he says they will choke the 350, it ****ing will.

I need to clean up these **** 350 heads I have laying around and throw them on.


Im tired of running the 305's :doah::(
 
4X4HIGH said:
If you put 305 heads (58cc chambers) on a 350 (85 350 heads have 76cc chambers) you will end up with way too high of a compression ratio and the engine will ping severely. The difference is about 2 point of compression, so if you started with 9:1 you'll end up with 11:1.
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Yeah except plenty of 350's come with 64 cc heads. And from 76 down to 52 isnt 2:1 increase its more like a 1:1 from everything I've read. Theres nothing wrong with 52cc heads on a 350 with the proper deck, pistons, and head gasket. PLENTY of camaro and transam guys do it for a low buck motor build.

As I said, port, polish, and maybe open the combustion chambers up a couple cc's. You put larger vavles in and 416s are damn good heads. Look all over thirdgen.org.
 
You're now trying to preach to the wrong guy. I do this for a living. From 58cc to 76cc is a 2 point jump in CR. There is no 350's that come with 64cc heads. The later TBI heads are somthing like 67cc's but the pistons are also a dished piston which keeps the CR down around 9:1.
 
Stomis said:
Ummm alot of guys run 305 heads on 350s. I wouldnt recommend it for a truck but as far as building a budget motor the 416 casting 305 HO heads with some at home port and polishing and bigger valves are 350+ hp performers.
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I got a set of 416's , I ain't putting em on a 350 ...... a nice old school 283 would love them though , with some flattops and nice intake , in a light car like a duece Nova .

350's need a little more breathing than the proverbial breathing through a straw when its a 100 degrees out , and running around the block :wink1:
 
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