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Thinking about the 383 buildup again....

Discussion in 'The Garage' started by TX Mudder, Jun 14, 2003.

  1. TX Mudder

    TX Mudder 1/2 ton status

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    I've got a little cash saved up and i'm thinkign about the 383 buildup again.
    All I have now is the 4-bolt 350 block that I need to take to the machine shop for a bore and general check-out. I don't have a lot of experience with machine shops, so what is an OK price for an overbore and cleaning/checking? Don'
    t want to get ripped.

    I like the powerhouse 383 kit (see it HERE) for $469.

    I like the World S/R Torquer heads 76cc for $370 each. They are 2.02/1.6 with 170cc runners, good for .560 max valve lift.

    I also like the Edlebrock Air-Gap intake for $200.

    All this would be 9.5 compression. Do you guys think I can run 87 or is that just asking too much? I like cheap gas.

    I don't know what cam to use. I would probably call the cam manufacturers and see what they recommend. No special voodoo on the engine, just a set of 1.5 roller rockers ($150 - $200)

    Anyone have opinions or some answers to the machine shop cost, the compression ratio on 87 octane, or anything? Again I don't have anything right now except the block.

    -- Mike
     
  2. blasterD

    blasterD 1/2 ton status

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    87 octane with 9.5:1 compression will be right at the limit. You will probably have to retard the timing a little to keep it from pinging. It would run really well on 92 octane though. I would say for 87 octane you shouldn't go any above 9:1. I think you might get slightly better gas mileage with the higher compression which may help to offset the higher cost for 92 octane.
     
  3. SUBFAN

    SUBFAN 1/2 ton status

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    Talk with the Camshaft guys. There are many things they can do with cylinder pressures to affect how it might work with 9.5cr and 87 octane. Sounds high, but it's prolly been done.....perfectly tuned....
     
  4. MousePowrd

    MousePowrd 1/2 ton status

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    Dont do it. Its not worth building an engine right and then being a cheapskate on gasoline.
    With iron heads do not go over 9.0 for 87 octane. All the magazines that say 9.5 is fine for pump gas are assuming 91 or 93 octane.

    What is the point of getting more compression, running cheap gas and losing power due to detonation?
     
  5. dyeager535

    dyeager535 1 ton status Premium Member

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    Combustion chamber design is going to have a huge effect on octane requirements. The torquers are "fast burn" style chambers aren't they?

    9.5:1 might be pushing it if you don't make sure the thing is in optimal tune, but it should be fine on 87 octane with decent heads.

    With everything *really* good, you can get to around 10:1 on 87 octane, but thats with AL heads and so on.
     
  6. MousePowrd

    MousePowrd 1/2 ton status

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    [ QUOTE ]
    Combustion chamber design is going to have a huge effect on octane requirements. The torquers are "fast burn" style chambers aren't they?

    9.5:1 might be pushing it if you don't make sure the thing is in optimal tune, but it should be fine on 87 octane with decent heads.

    With everything *really* good, you can get to around 10:1 on 87 octane, but thats with AL heads and so on.

    [/ QUOTE ]

    Not knocking the original poster, but 1 in 10 guys will keep up their tune well enough to prevent detonation at 10:1 on 87 octane with cheap iron heads. This is a work truck and will be generating a lot of cylinder pressure. Why take the chance for such a small amount of potential gain?
    If we were talking about something light like a Camaro it would be easier, but not with these pigs
     
  7. TX Mudder

    TX Mudder 1/2 ton status

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    They sell two different kits. For the 76 cc heads, I can choose between 9.5 or 8.5 CR

    8.5 seems a tad low, but what do I know. Anyone?

    -- Mike
     
  8. 1972Blazer

    1972Blazer 1/2 ton status

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    Why not spend the money and get a used forged 350 crank and rods and build from there with forged pistons. You will have a stronger bottom end to do anything you want later, like a real nice set of aluminum heads. Your 383 kit is a cast crank and a bunch of noname parts, I guess if that is what you want?

    You will be at the dividing line between regular unleaded and super unleaded. This is my engine and I use Super Unleaded all the time.

    1970 LT1 Block, Forged 350 crank, Forged pink rods, Forged TRW high dome pistons 10.5 to 1 compression ratio with 64 cc heads @ .030 overbore, 1970 LT1 2.02/1.60 heads fully ported and polished, Mallory unilite distributor, 3310 Holley 750 cfm, Holley Dominator Intake and a Lunati Cam with specs like this: Intake lift/duration .490"/290 degrees, Exhaust lift/duration .490"/297 degrees, Intake duration @ .050"/235 degrees, Exhaust duration @.050"/240 degrees, intake lobe centerline 107 degrees, Exhaust lobe centerline 112 degrees, this is all with a rocker arm ratio of 1.5. I figure a conservative 425 HP once the restoration is done I will dyno tune the engine. I put about 100 miles on it before I tore the Blazer apart, the engine is a Monster when you lay into it. 35" tires spin so easy!!!!
     
  9. 1972Blazer

    1972Blazer 1/2 ton status

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    I plan a good set of Aluminum Heads and a 150 hit of Nitros Oxide for Competition Hill at Glamis!!!! Oh and I need the paddle tires too.
     
  10. TX Mudder

    TX Mudder 1/2 ton status

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    All that stuff would be out of budget. This will be my second engine rebuild ever so I still don't want to spend big bucks. All that forged stuff is big bucks to me. Hell, even the $1500 or so this will cost is bigger than I want to spend, but you gotta do what you gotta do.

    -- Mike
     
  11. 1972Blazer

    1972Blazer 1/2 ton status

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    I understand, I was just making a recomendation to spend the money now on a strong bottom end that you can add more to later.
     

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