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Old 05-17-2010, 03:45 PM
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bigger valves on a 305

hello its been a while since the last i have posted anything,
i was just wondering what the biggest set of valves you can put on a stock 305 bore with out milling



a little info on my engine
its a 1976 305 with torker II intake stock 60cc heads, headers
600 CFM electric choke holley, hei distributor new plugs and wires and a 2800-3500 stall converter connects it with a th350 to stock 3.08 rear gears

all the help is well appreciated

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Old 05-17-2010, 05:00 PM
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What is the casting no. of the heads?
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Old 05-17-2010, 05:14 PM
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I would use 416 heads. It's cost less than installing bigger valve.
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Old 05-17-2010, 08:47 PM
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As mentioned use the 416 castings. You can have them moved up to 1.94 valves but the chamber would have to be swept, if not it`ll shroud the bigger valve and it`ll flow less than the smaller valve did. Get rid of the Torker intake, it`s made for mid range and upper RPM performance. The 305 is a small cubic inch engine and needs all the torque it can get, this is why the factory used intakes on them with smaller runners for high velocity. The torker intake has little velocity at low RPM which will make the engine a dog, especially with the 3.08 gears. I would replace it with a basic edelbrock performer or weiand action plus.

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Old 05-17-2010, 08:59 PM
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thats why he has a high stall converter. Do u want to make this run right? u can upsize to 194 valves but u may not be able to have more cam. bc of the valve to piston clearance becomes less with the valve at an angle and larger diameter.
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Old 05-17-2010, 09:02 PM
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u could always hog out the heads, port polish bowl work, guide boss reshaping. gasket match. and polish the chambers all at home. just a good valve seat and face regrind and a .020 mill off that`d boost u some extra power.
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Old 05-17-2010, 09:07 PM
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edelbrock performer intake works well. What camshaft are u running? is that a roller cam block? if so the stock camshaft will suffice. i once put together a 305 with stock refreshed pistons and bottom end. with a set of 267 heads. fully race prepped only thing is the smaller valves didnt account for much HP, just butt loads of torque. with a performer intake and a quadrajet. polished venturis and set to specs. re curved timing. stock exhaust manifolds and dual exhaust with flomaster dual chamber mufflers with 2.5 inch piping. it ran very very good i must say. I am currently rebuilding my six cylinder mustang. i am working on the heads right now. the machine shop wont attempt to make a simple mill job for me to install a 2brrl. so im just planning on changing the carb.
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Old 05-17-2010, 09:25 PM
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Quote:
Originally Posted by velle307
what the biggest set of valves you can put on a stock 305 bore with out milling
The practical limit is 1.94" intake. I don't see a reason you couldn't use 1.6 exhaust valves, although mostly you'll see the exhaust stay at the stock size, 1.50".

Unshrouding the valves is recommended, this may require milling the head to retain the right chamber size so the CR is correct.
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Old 05-17-2010, 09:58 PM
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With a low torque output of a 305 with that intake, even with a true 3500 Stall I`d be surprised if it stalled to 2200. A open plane intake has no place on a street bound 305. This is why we try our best to match components, because when you match then the engine can make max power with the given combo. The torker is lop sided for this package, one reason why is with such a high gear the cruise RPM at 55 is likely under 2500 which is where the power is falling off at due to the intake. With that gear, open intake, small cubic inches, stall it and it likely won`t even burn a tire. Stick a dual plane on it and it`ll roast the tire off.
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Old 06-10-2010, 02:04 AM
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well you already have a lot less space to fix the valves in there
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Last edited by engineczar; 06-10-2010 at 06:35 AM. Reason: Advertising. Please see: commercial posting guidelines.
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