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Thread: budget build questions for the advanced tuners 6825 ecm $0d bin

  1. #16
    Super Moderator dave w's Avatar
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    I'm thinking a 283 with 882 heads (about 76cc if I'm remembering correctly) will have a compression ratio that will be to low.

    dave w

  2. #17
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    I agree with Dave. The 882 heads will make it tough to get the compression ratio you want. It's not too hard to slot the center bolts in the manifold but it doesn't look pretty afterward. What about buying a used set of heads? www.car-part.com?

  3. #18
    Fuel Injected! jim_in_dorris's Avatar
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    I might pick up a head from the machine shop, or try to find a set of 58cc center bolt 305 heads, but the 882 heads are already paid for. Yes the compression ratio is low. I used my dcr calculator to get 7.9:1. I wish I could just afford new heads, but that money thing is a problem. I will probably bite the bullet and get another 193 head, then pay to complete the head I have.
    Square body stepsides forever!!!

  4. #19
    Fuel Injected! jim_in_dorris's Avatar
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    Well thinking about the 305 heads, but 9.7:1 seems a ltitle high. So I guess I will wait and get another 193 head.
    Square body stepsides forever!!!

  5. #20
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    7.9 is low and you're dealing with an old chamber design so fuel economy might be low. It would run but I'd keep an eye out for a smaller chamber version. Maybe someone has reasonably priced set near you?

    https://klamath.craigslist.org/pts/6052760055.html

    https://medford.craigslist.org/pts/6060150751.html

    https://medford.craigslist.org/pts/6044010787.html

    https://medford.craigslist.org/pts/6041504992.html

  6. #21
    Fuel Injected! jim_in_dorris's Avatar
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    Thanks 1project, I hadn't gotten to looking at craigslist yet. I may go look at the set in Klamath Falls tomorrow if the machine shop doesn't have something interesting. I know the 882 heads aren't the greatest, but they were on that 283 in my son's Nova, and it ran pretty good, just the cam was too much for how it was geared. I have pretty much talked myself out of using them, so that means finding something else. a set of 350 vortec heads? I think they were 64cc combustion chambers also. A few more ponies, and torque. Maybe I can find a set that isn't trashed.

    <edit>

    Well, 4 hp and 5 lbs of torque may not pencil out as a good bang for the buck with having to buy an manifold as well. I spend too much time doing cost analysis.
    Last edited by jim_in_dorris; 03-29-2017 at 09:30 AM.
    Square body stepsides forever!!!

  7. #22
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    That's not much gain. You might see greater fuel economy with the new heads but it's hard to predict that. Ultimately if putting the engine together with parts you have gets the truck on the road and helps you get in a better place later, that's probably the best way to go.

  8. #23
    Fuel Injected! jim_in_dorris's Avatar
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    I found a set of 191 heads that are rebuildable, not much more then new springs, seals, 50 up locks and hand lapping. $150.00
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  9. #24
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    I'd give a set of L30 305 heads a try, they have a 58cc chamber IIRC.

    L31 is rated at 255hp@4600rpm/330lb/ft torque@2800rpm
    L30 is rated at 230hp@4600rpm/285lb/ft torque@2800rpm

    Both engines use the same 191º/196º 0.412"/0.428" 111º LSA roller cam
    The L30 305 is hampered with the single cat exhaust, while the L31 350 gets the better dual cat exhaust
    Both engines use the same air intake, MAF, t-body, intake, injectors, manifolds, fuel pump FPR etc.

    The L30 is only 25hp/45lb/ft torque down on the larger by 45cid 350.

    the L30 heads can be had for much less than the 350 heads as well, look for numbers '520 and 059 for the 305 L30 heads.

    But yes, you require the Vortec intake manifold.

    peace
    Hog

  10. #25
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    I'd give a set of L30 305 heads a try, they have a 58cc chamber IIRC.
    I was very disappointed when I learned the L30 head did not receive the same development work as the L31 version. The L30 head is similar to the previous L03 other than the 8 bolt intake pattern and lack of exhaust crossover passage.

    L30:


    L03

  11. #26
    Super Moderator dave w's Avatar
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    I've been wondering about the intake valve clearances vs. bore diameter with the 283. Is it possible the 1.94 intake valve will interfere with the 3.875" bore diameter of the 283? I seem to remember when I used a set of 305 heads with the 1.84" intake valves on a 283, there was just barely enough cylinder wall to intake valve clearance to be on the safe side for a mild performance 0.460" lift camshaft.

    dave w

  12. #27
    Fuel Injected! jim_in_dorris's Avatar
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    Good catch dave, I will double check. The 882 heads cleared, but have a really large combustion chamber. Hopefully the 191's will clear.
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  13. #28
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    Quote Originally Posted by 1project2many View Post
    I was very disappointed when I learned the L30 head did not receive the same development work as the L31 version. The L30 head is similar to the previous L03 other than the 8 bolt intake pattern and lack of exhaust crossover passage.

    L30:


    L03
    They have a very similar chamber to the 14022601 truck 305 HO heads. I had a 1983 G20 Van tha had thise heads. It ran very well with those 53cc heads. The 059s and 520s have a very abreviated swirl ramp and also do not require much timing to get good results. I think with the smaller bore they just did not require the chamber rework to get the results GM wanted. They still flow mid 220s on the intake port and have the same exhaust flow as the L31. I have a 305 L30 with a Lunati 268 High Efficiency flat tappet cam in a 1999 Tahoe. The power it makes is on par with a stock LM7 5.3.

  14. #29
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    Quote Originally Posted by dave w View Post
    I've been wondering about the intake valve clearances vs. bore diameter with the 283. Is it possible the 1.94 intake valve will interfere with the 3.875" bore diameter of the 283? I seem to remember when I used a set of 305 heads with the 1.84" intake valves on a 283, there was just barely enough cylinder wall to intake valve clearance to be on the safe side for a mild performance 0.460" lift camshaft.

    dave w
    That is interesting....I have run 1.94/1.60s on a .030" over 305 which is a 3.765" bore and it had plenty of clearance. 059 heads BTW. At .600" lift it had more than .100" valve to bore clearance. Offset dowls could have even increased that.

    This is a 1.94/1.50 valve on a stock 3.735" bore 305 block at .0600" lift. Tested without a head gasket. A 2.02" valve would hit as soon as it came out of the chamber...About .0420"

    Last edited by Fast355; 04-01-2017 at 11:14 PM.

  15. #30
    Fuel Injected! jim_in_dorris's Avatar
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    Good to know. I am concerned that 53cc combustion chambers with the flattop pistons will put me up over 10:1 compression, not exactly sure I could tune it properly. The 191 heads will yield 9:1, something that seems safer on an older motor with miles on it.
    Last edited by jim_in_dorris; 04-02-2017 at 02:40 AM.
    Square body stepsides forever!!!

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