Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

school me about heads. Power increase idea

Discussion in 'The Garage' started by 78Suburban, Apr 12, 2006.

  1. 78Suburban

    78Suburban 1/2 ton status

    Joined:
    Jul 4, 2005
    Posts:
    2,609
    Likes Received:
    0
    Location:
    Georgia
    What motors had 64cc combustion chambers? I think both sets of heads on my 350's are 75cc heads. What would my compression ratio raise to? If I swapped on heads with a smaller combustion chamber, how much power increases could I get, if I ran premium fuel and played with the timing? I'm just looking for cheap scrap yard power modifications. I'm not very familiar with what heads were offered for from the factory.
    thanks
     
  2. boz42

    boz42 1/2 ton status GMOTM Winner

    Joined:
    Jun 3, 2003
    Posts:
    3,181
    Likes Received:
    0
    Location:
    Hopewell, Tn 38058
    some of the 305 heads were very small chamber, i can't remember the cast # any more. in my opinion it is not the compression that helps as much as the design of the head. usually a small cc head has better runner design cause it is more performance orientated. like the old double hump heads.


    friend of mine is in r&r at comp & he runs the dyno. he says 1 point of compression is basically 10-20 horse through the entire rpm band.
     
  3. neverendingproject

    neverendingproject 1/2 ton status

    Joined:
    Jul 24, 2005
    Posts:
    1,637
    Likes Received:
    0
    Location:
    Tulsa, OK
    Usually, 305 heads are 58cc. Vortecs and a lot of vette heads I think are in the 64-68cc
     
  4. 78Suburban

    78Suburban 1/2 ton status

    Joined:
    Jul 4, 2005
    Posts:
    2,609
    Likes Received:
    0
    Location:
    Georgia
    So are 305 heads too small? Will they bolt right on? Will they restrict flow alot? What would my compression ratio be? I'm sure there's gotta be a good reason not to do this. If not, it might be a good idea. Anyone ever done/ thought of this? Can sombody check 75cc heads against 58cc heads on a 350 in a desktop dyno? I'm a noob about these kinds of things and just looking for ideas.
    thanks
     
  5. neverendingproject

    neverendingproject 1/2 ton status

    Joined:
    Jul 24, 2005
    Posts:
    1,637
    Likes Received:
    0
    Location:
    Tulsa, OK
    305 heads suck for anything other than 305's plain and simple. Go with some sort of High compression 350 heads or vortecs if you have the money.
     
  6. roadnotca

    roadnotca 3/4 ton status

    Joined:
    Sep 16, 2005
    Posts:
    5,433
    Likes Received:
    1
    Location:
    Redondo Beach, CA
    Everything you've ever wanted to know. ISBN 0-87938-357-7, MBI Publishing 1989.

    P4120376.JPG
     
  7. 1977k5

    1977k5 3/4 ton status Vendor

    Joined:
    May 26, 2003
    Posts:
    9,991
    Likes Received:
    130
    305 heads had small valves and sh**ty flow numbers. Don't bother. Aftermarket or vortec is the only thing worth your time and money, IMO.
     
  8. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

    Joined:
    Jan 23, 2006
    Posts:
    11,228
    Likes Received:
    485
    Location:
    New Hampshire
    My 305, because it is an L69 out of a Firebird has about a 9.5:1 compression with those 58cc heads and flat top pistons. I am now looking for something that flows better because 305 heads came at a time of the height of the smog era so they were very restrictive despite the high compression. Like 38377k5 said, go aftermarket or vortec. That is your best bet to get more power.

    I'd imagine your 350 would have at least a 10:1 compression, depending on your pistons, dished or flat top.


    Man do I love COMPRESSION!!!!!
     
  9. roadnotca

    roadnotca 3/4 ton status

    Joined:
    Sep 16, 2005
    Posts:
    5,433
    Likes Received:
    1
    Location:
    Redondo Beach, CA
    X2. I bought Edelbrock.:D
    <=============
     
  10. mountainexplorer

    mountainexplorer 1/2 ton status

    Joined:
    Nov 14, 2001
    Posts:
    4,903
    Likes Received:
    0
    Location:
    Spokane, Wa./Ione, Wa
    I ran a set of 041 casting 64cc chamber head on my SB400. They way it was set up with flattops and the rods in the motor it was running about 10.5:1 compression. It ran strong until it flew apart (guy who checked my heads didn't replace valve guides, and one wore out so bad a valve wobbled around so bad it broke the head off and shattered a piston and demolished the rest of the motor).

    Right now, I'm about ready to bolt on a pair of the camel hump heads with accessory holes (186 casting#) onto a new 350 shortblock with flattops. They are also 64cc. I'd guess it will be like 10.25:1.

    Since both of these heads were originally of a 350 or 302/327 from the late 60's/early 70's, they have larger runners and have 1.94 intake valves. The 305 heads may raise compression even more being 58cc, but like already said, flow decreases alot because of the smaller intake runners and smaller valves.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,975
    Likes Received:
    189
    Location:
    Roy WA
    Not to mention that the valves are shrouded because the bore is physically smaller on a 305, and the combustion chamber is as well to match.

    If you could get a set of used Vortecs and weren't planning on anything other than a mild carbed applicaiton, as heads go they are the ticket. A pair of L98's from a Camaro wouldn't be bad, but still not as good as Vortecs.
     
  12. ZooMad75

    ZooMad75 1/2 ton status Premium Member GMOTM Winner

    Joined:
    Apr 5, 2003
    Posts:
    998
    Likes Received:
    592
    Location:
    Pueblo, CO
    Stock Vortecs out-flow stock camel hump heads. Plus the vortec combustion chamber is a more modern high-swirl design which is very efficiant. There's a ton of them in boneyards as compared to camelhumps. Also since the camel hump heads haven't been made in 30+ years, what supply that is left has already been rebuilt/trashed a couple of times at least. Besides, everybody selling camel hump heads seems to want a lot of money, even for ones that need rebuit again.

    There are draw backs to the Vortecs too. First is the intake bolt pattern, 8 bolts vs 12 on a non-vortec SB. You have to get a Vortec intake. Edelbrock makes at least 5 versions, GMPP has 2 and Power Plus has a couple too. However, one untapped source for Vortec carb'd intakes is the Marine industry. Mercruiser, volvo-penta and I think one other have sold 350's under there own brands that had Vortec's and ran q-jets. These used a Cast Iron intake with the right vortec intake bolt pattern. They pop up on ebay fairly regularly, you just got to search for them. They are usually cheaper than the other ones mentioned.

    The other main drawback is valve retainer to valve guide clearance issue. This is when the spring is fully compressed (valve open) if the lift on the cam is too much, the retainer will hit the top of the valve guide. Most report max lift with stock vortecs can't exceed .490". If your cam is smaller than that no problem. If it is larger you got to machine the guides down and use smaller aftermarket seals. At the same time you should open up the spring pocket to allow the use of regular size SB springs. (Vortec springs are slightly smaller in diameter). You can get a tool from one of the cam compaines to do both jobs or have your machine shop do it for you.

    If you are looking to install the heads on a fairly stock engine the vortecs would give the most bang for the buck. (small cam, no mods needed to the spring/guides). Surf ebay or the Marine shops for the intake.

    I'm getting ready to actually remove a set of Camel-back heads from the 327 in my dad's 57 Nomad to replace them with Vortec's. Yes the camelbacks have been on that engine for 35+ years so they probably are quality cores to rebuild, but they don't have the hardend exhaust seats and would still need work done to them. I got a set of Vortecs for next to nothing and he sent them out to get the guides machined and spring pockets enlarged. Put them back together with stock valves and Z28 spec springs and they are ready to go($110 for the work done). He found a GMPP intake on Ebay for about $125 (less than half the dealer list price). When we swap the heads we will ditch the 60's style "30/30" solid lifter cam for a L-79 Hydraulic (.448 lift). All in all, we should have about the same power with better drivability over the 60's vintage stuff. All total, we've got less than $300 bucks in the parts to convert to the vortecs. Shop around, there are better deals to be had on Vortecs than the old camelback stuff.
     
  13. 1977k5

    1977k5 3/4 ton status Vendor

    Joined:
    May 26, 2003
    Posts:
    9,991
    Likes Received:
    130
    For anyone considering buying used vortec heads, they are somewhat notorious for cracking. Make sure you check that out before picking them up.
     
  14. neverendingproject

    neverendingproject 1/2 ton status

    Joined:
    Jul 24, 2005
    Posts:
    1,637
    Likes Received:
    0
    Location:
    Tulsa, OK
    YES!!! I got a pair and only one was good. I went 3 months and 3 heads before I found one that wasnt junk.
     
  15. R77K10

    R77K10 Banned

    Joined:
    Mar 15, 2006
    Posts:
    564
    Likes Received:
    0
    Location:
    Lincoln IL
    the L69 305 were same as LG4 and Lg3 and other 305 engines except the pistons and cam

    the heads were same 58cc

    4416 casting heads was the most common 58cc 305 head and was used on L69 and non L69 both extremely commonly

    they are good heads they dont crack and its easy to stick 1/94 valves in them and run them

    all heads sbc 55-95 265-400 will bolt on, except LT1

    not including the centerbolt head change in 87

    but they bolt on too

    same

    ive run 4416 305 heads with 1.94 valve put in them, on old 350 engines and they run badass

    stock intake and stock carb and cam but .030 flat tops TRW and they run wicked good low end torque to blast it off the line with

    low end torque is fun!

    but if youre wanting to race and run high rpm then youll want to build it for horsepower instead

    but to sacrifice low end torque


    i prefer torque over horsepower, horsepower is overrated unless youre seriously racing track

    imho


    good luck
     
  16. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

    Joined:
    Jan 23, 2006
    Posts:
    11,228
    Likes Received:
    485
    Location:
    New Hampshire
    What needs to be done to get a 1.94 valve on there?
     
  17. dyeager535

    dyeager535 1 ton status Premium Member

    Joined:
    Dec 13, 2000
    Posts:
    26,975
    Likes Received:
    189
    Location:
    Roy WA
    Where exactly do they crack? I keep hearing about it, so I know it happens, just never hear where the problem spots to look are.
     
  18. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

    Joined:
    Dec 14, 2001
    Posts:
    22,059
    Likes Received:
    69
    Location:
    Pleasanton, CA.
    Almost every chevy head that cracks will crack in the 2 center cylinders from an exhasut seat up across the combustion chamber and onto the deck surface of the head.

    Also 305 heads came with both 1.72" intake valves and also 1.94" intake valves.
     
  19. projectcop

    projectcop Registered Member

    Joined:
    Jul 13, 2005
    Posts:
    10
    Likes Received:
    0
    Location:
    northern california
    If you are scrounging through junk yards for your heads, look for a set of 441 or 041 heads. with a mild cam, they will give you some decent torque numbers.
     
  20. Chevy305

    Chevy305 6 Lug 14bsf Status Premium Member GMOTM Winner

    Joined:
    Jan 23, 2006
    Posts:
    11,228
    Likes Received:
    485
    Location:
    New Hampshire
    How do I tell what size valves my engine has?
    I found these #s on the front of the engine:
    V0613DDY
    10N175266

    If that helps
     

Share This Page