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vortec heads on a 305

This is a discussion on vortec heads on a 305 within the Classic Muscle forums, part of the Vehicle Specific category; my buddy is throwin together a 305 probly gonna be bored .030 over. can he run some vortec heads and ...

  1. #1
    Powerstrokin LT1 > LS1's Avatar
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    vortec heads on a 305

    my buddy is throwin together a 305 probly gonna be bored .030 over. can he run some vortec heads and a decent little cam with them?

    its a low budget project to put in his S-10.

    and will a 3.75" crank fit or will the block need machining?

  2. #2
    ʢ ൧ ൨ ൩ ൪ ൫ ൬ ൭ ൮Ր Ց Ւ Փ Smittro's Avatar
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    http://www.chuckschevytruckpages.com/enginespecs.html

    Nope. 3.75 stroke is listed as a 400..

    V8 - 305 bore 3.736/ stroke 3.48
    Last edited by Smittro; 09-10-2009 at 04:01 PM.

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    BORED .030 305 = 310.11354 cu. in.
    BORED .060 OVER = 315 cu. in.

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    your parts guy!!! 1fastcamarosss11's Avatar
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    trans am 00 ws6
    1998 camaro ss vert

    there is a kit out there that will get you to 335 ci. i forget the name of the place i'll see if i can find it.

    found it but it is 340.
    http://www.speedomotive.com/ps-26-8-...crank-kit.aspx
    if he is looking for a 350 block i have a great set up i would sell for cheap everything is brand new from summit all still in the boxes. should make around 400 hp. pm me if interested.

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    Powerstrokin LT1 > LS1's Avatar
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    well, his block has some issue. a couples of the bores are lookin a little nasty, but we will wait and see on what his plan is. he budget is really really low.

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    your parts guy!!! 1fastcamarosss11's Avatar
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    trans am 00 ws6
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    Quote Originally Posted by LT1 > LS1 View Post
    well, his block has some issue. a couples of the bores are lookin a little nasty, but we will wait and see on what his plan is. he budget is really really low.
    i have a few 305, and a 350 if interested.

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    Powerstrokin LT1 > LS1's Avatar
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    well, I just measured the bore and stroke.

    turns out its a 307 motor. so we can bore it .030 over to 3.905" and maybe do a stock 350 crank to come up with decent cubic inches. still wantin to do vortec heads

    shootin for a lil over 300hp

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    Senior Member bigrondownhiller's Avatar
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    What is the budget? For the price of machine work and parts needed you might be able to get one of these for around the same price and have some more performance. First one is a brand new engine. http://www.sdparts.com/product/10067...350Engine.aspx.

    http://www.summitracing.com/parts/MLL-BP3551/
    Last edited by bigrondownhiller; 09-17-2009 at 04:16 PM.

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    link no worky bro

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    Senior Member bigrondownhiller's Avatar
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    Fixed.

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    Moderator Firebirdjones's Avatar
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    300 hp is isn't hard to achieve with the 307. The only thing that kills it is the small bore. It has the same crank as the 327 had with 3.250 stroke.
    I'm not too sure you could drop in a 350 crank with a longer stroke and then come up with pistons with the taller pin height required to fit the small 307 bore. Would probably be a custom piston.

    If you are dead set on building the 307 I'd stick with the stock crank. The bore will only allow a 1.94 intake valve head at the most. May be a point of diminishing returns though as it would be shrouded by the bore. The combustion chambers would have to be pretty tight just to keep a decent compression ratio. Vortec heads have a 64cc chamber, which is right about where the stock 307 heads were and they only had about 9:1 compression at best. I cc'd my 307 heads but I'd have to check my notes as to what they came in at,,,I did mill them another .020 though to bump the compression a tad.

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    Quote Originally Posted by Firebirdjones View Post
    300 hp is isn't hard to achieve with the 307. The only thing that kills it is the small bore. It has the same crank as the 327 had with 3.250 stroke.
    I'm not too sure you could drop in a 350 crank with a longer stroke and then come up with pistons with the taller pin height required to fit the small 307 bore. Would probably be a custom piston.

    If you are dead set on building the 307 I'd stick with the stock crank. The bore will only allow a 1.94 intake valve head at the most. May be a point of diminishing returns though as it would be shrouded by the bore. The combustion chambers would have to be pretty tight just to keep a decent compression ratio. Vortec heads have a 64cc chamber, which is right about where the stock 307 heads were and they only had about 9:1 compression at best. I cc'd my 307 heads but I'd have to check my notes as to what they came in at,,,I did mill them another .020 though to bump the compression a tad.
    You're right 350 crank will not work. But I believe he's boreing out a 305, of which I've posted the two most common over bores. Maybe if he found an old set of camel back heads 2.02I 1.94E. Possibly he could use them after the over bore of.060 bringing it to a 315 cid..

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    Moderator Firebirdjones's Avatar
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    Quote Originally Posted by Smittro View Post
    You're right 350 crank will not work. But I believe he's boreing out a 305, of which I've posted the two most common over bores. Maybe if he found an old set of camel back heads 2.02I 1.94E. Possibly he could use them after the over bore of.060 bringing it to a 315 cid..
    Oooops my bad. You are right. For some reason I was thinking 307. The 305 is a different animal with a very tiny bore and a 350 crank.

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    327 has a 4.01 in bore and 3.25 in stroke..Advertised displacement 327 ci actual displacement 326.7 ci.....Max overbore is 0.060 in...It was produced through 62-69....Horsepower range 150-235 net 210- 375 gross...adv. compression ratio 8.75-11.25:1....Main journal diameter 2.30 in 62-68.....2.45 in 68-69....Rod journal diameter 2.00 in 62-68.....2.10 in 68-69....Conrod-rod center to center 5.7.... Con_rod bolt diameter 11/32 in 62-68....3/8 in 68-69....Main bearing cap two bolt.Crankshaft forged steel 62-68....cast iron 68-69....intake-valve size 1.72/1.94/2.02 in
    Last edited by Smittro; 09-17-2009 at 07:45 PM.

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    No you're are right I just rechecked he say's it turned out to be a 307. But the 327 crank has smaller mains than the 350.. So my bad man..

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    He could punch it out and hit his target of 300hp, with 9.50 CR or 10.0CR good cam and some nice headers.. should'nt take too much for 300 crank hp..
    The earlier years had steel cranks and cast cranks for like 2 years before productoin ended..
    Last edited by Smittro; 09-17-2009 at 08:24 PM.

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    okay, so if we leave the 3.25" stroke, and bore it about .030 over, and do a decent top end, we should be around 300 hp?

    it should like to rev with that short of a stroke.

  19. #19
    Moderator Firebirdjones's Avatar
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    Quote Originally Posted by Smittro View Post
    No you're are right I just rechecked he say's it turned out to be a 307. But the 327 crank has smaller mains than the 350.. So my bad man..
    Oh okay, I thought I was losing my mind,,,lol

    The 327 only had the smaller mains up through 1967. Starting in 1968 they all had the same size mains whether it be a 307, 327, or 350.

    So in essence, there are 2 different types of 327 cranks out there. Smaller mains for the early year 327's from 62-67,,,and larger mains from 68 on up. Although 327 production started to slow at that point when the 350 was introduced in 67.

  20. #20
    Moderator Firebirdjones's Avatar
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    Quote Originally Posted by LT1 > LS1 View Post
    okay, so if we leave the 3.25" stroke, and bore it about .030 over, and do a decent top end, we should be around 300 hp?

    it should like to rev with that short of a stroke.
    Ya it would like rpm. I have been playing around with the original 307 in my 71 ventura. Still stock bottom end with 70K miles, I had the original heads off, milled .020 for a bump in compression (originally 9:1) and I did some slight pocket porting on the short turn radius. Still stock size 1.72 intake valves and all.
    Then stuck a small comp cam extreme energy 262 in it. Which is 218/224 at .050 duration with .462/.470 lift. on a 110 lobe sep. About all the cam I could put in without running into retainer/valve guide clearance problems. Any more cam would have required more machine work on the heads.
    I then installed a 2101 edelbrock performer intake I had laying around, and stuck a 600 double pumper holley I had,,,and a set of 1 5/8 hooker headers.
    That's it. Runs damn good for what it is. With a 2.54 muncie and only a 3.08 rear I've run 14 teens at 99 mph with the car on stock tires. I shift at 6,000 rpm,,,afraid to run higher with stock bottom end, but it acts like it wants more. People just don't believe it's a 307. Runs circles around my neighbors 67 390/4-speed mustang,,,hahaha.

    So ya they can be decent performers. I'm not sure if mine is even making 300 hp,,,probably more like 280 ish. But I do remember Car Craft doing a 307 buildup a while back.
    They used the same camshaft I used, as well as the same intake manifold. The difference was they installed a set of Edelbrocks E-tec aluminum heads. Compression was around the 9:1 mark. They also had a stock low mile bottom end that they didn't touch either.
    They dyno'd that little thing at 315 HP. So it's doable.

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