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Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Skroo, Apr 13, 2003.

  1. Skroo

    Skroo 1/2 ton status

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    I've got a 350 shortblock with flat top pistons today that I'm gonna rering and run till I can afford my 383. I've got a 1983 305 in my truck that i'm gonna steal the heads off of. I know that the ports are way too small but i'm trying to keep the budget below $350 to $400 and I don't plan on pulling it past 4500 rpm. I'm gonna order one of PAWS $80 cam/lifter sets so I need some specs. I'm thinking i need a cam with mild lift, lots of duration and small overlap to make up for the crappy heads. What do yall think?
     
  2. Z3PR

    Z3PR Banned

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    I think a 350 with flattop pistons, and 58cc heads will be way to high of compression for pump gas. I think it sounds like major detonation problems even with 91 octain gas.
     
  3. Skroo

    Skroo 1/2 ton status

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    I did'nt think about that. I'll probally have to look for some cheap heads. I might be able to get some mid eightes heads from a friend cheap. There goes my dirt cheap engine plans. /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif /forums/images/graemlins/frown.gif
     
  4. Z3PR

    Z3PR Banned

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    If you can find some 64cc heads, that SHOULD give you approx. 10 to 1 compression with flattop pistons.
     
  5. BayouBlazer88

    BayouBlazer88 1/2 ton status

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    What grade gasoline do you recommend running with 10 to 1 compression?
     
  6. monte0172

    monte0172 1/2 ton status

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    I have a 86 chevy truck with a 327 10-1 compression pistons and 58cc heads which are ported and polished then i ran steal shim headgaskets which give you another .5 compression for a total of approx 11-1 and I run 93 with no detonation at all. The secret to it is buy a decent HEI High output coil like hypertech or DUI. this will fix your detonation problems. Dont buy a cheap accel it wont work and you will burn it up.
     
  7. bablazer73

    bablazer73 1/2 ton status

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    You can get away with higher compression with a flat top piston vs a dome piston. The flat top has a better flame pattern and won't cause hot spots that domes do. But a good ignition will be needed. With the 305 heads, with small ports you can make a ton of torque. you might want to "clean" the ports up. not really port them just clean some of the casting flaws. This will help them flow alot better. I would keep the "advertised duration" between 260-270. with around .450 valve lift. I would also look for a cam that has a little more lift/duration on exaust side. I have used the PAW cams. decent and cheap.
     
  8. Z3PR

    Z3PR Banned

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    I've always ran a min. of 91 octain without any problems. But then again, I did have a MSD ignition system.
     
  9. Skroo

    Skroo 1/2 ton status

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    What if I got the pistons machined with a small dish (4 to 6 cc) and a set of thick head gaskets. That should get it down to around 9.5 to 10. If that would work, how much would the machine work cost.
     

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