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Help me build my engine.

Discussion in 'The Garage' started by zcarczar, Jul 28, 2004.

  1. zcarczar

    zcarczar 1/2 ton status

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    I picked up a good builder this week through work. I got a '99 vintage Vortec 350 with a knocking rod. Its a roller block and the heads are in bitchin shape so I thought I would use it to build my new engine. Now I have a few questions...

    Its a 2 bolt block, will I need to convert it to 4 bolt mains if its going to see 6000 RPM and nitrous regularly? I plan on studding the main caps either way. Its also going to be stroked.

    Do I *need* to run roller rockers, chromoly push rods and guideplates? The tech I work with said he likes to run them and they would probably work good on my engine, especially if it runs lots of high RPM's. Im already planning on studding the heads and prepping it to run around a .500 lift cam.

    Forged or Cast crank? Will I be exceeding the limits recomended with a cast crank with a 150 shot of nitrous, and 6k RPM?

    Anything else I should look out for? Anybody have a good recomendation for a set of resonably priced forged pistons for a 383 that are dished so I dont have 10.5:1 compression with my 64cc heads.
     
  2. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    If you want NOS and 6 grand ( sounds like mud or street ) build the bottom end as stout as you can . Yes I would run roller rockers , less friction , more of a dead on ratio than stamped rockers ( even newer style ) , which can vary quite a bit . Actually a 2 bolt block is a good candiate for being "splayed" , where you add new maincaps with angled bolts and drill the block for 4 bolt mains /forums/images/graemlins/k5.gif
     
  3. Hossbaby50

    Hossbaby50 3/4 ton status

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    Forged crank if you want it to survive the nitrous. Cast crank if you want to see holes in the oil pan.

    Roller valve train is a very nice thing to have.

    Stroked motors don't like to see high RPM. 383's are usually good to around 5500 max because of the bore to stroke ratio. If you want high RPM destroke a motor. Take a 400 block and put a 350 crank in it. 377 destroker. They will rev to the moon. Or just punch the 350 .030 over and run a 355. A 355 with a good valvetrain and cam will rev high too.

    On a 2 bolt block have the main caps splayed. It will make them stronger then a 4 bolt block.

    I am not sure how well a set of Vortech heads will breath at that RPM. I think they may be out of flow by then.

    Are you going to run FI or carb?

    Harley
     
  4. zcarczar

    zcarczar 1/2 ton status

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    this truck is an all around truck actually. Does a lot of street, some mud, a lot of trail riding, and a lot of high speed dezert running and sand, lots of sand. Thats why I got a Nitrous kit, and want an engine that can rev high.

    I geuss I will pony up and get the Milodon caps. I doubt im going to need forged rods in this combo, but a forged crank would be nice.

    Truck is FI, will stay TBI. My dad is running a TBI pumped up 406 in the crawler(SMP's old rig) and it works bitchin, throttle response is awesome, will smoke the tires no problem on dry pavement.
     
  5. el diablo

    el diablo Registered Member

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    2 bolt mains can handle up to 500HP. With splayed caps more.
     
  6. Hossbaby50

    Hossbaby50 3/4 ton status

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    TBI will not flow that much air. You will need to upgrade the throttle body on that to at least a 454 TBI (still only flows 670 CFM) otherwise you will not see any real power above 4000 RPM. You will be out of air long before you ever reach the 6K mark you are looking for.

    TPI is good in stock form to about 4500-4800. Upgraded it can go much higher. Upgrading is not cheap though. Highflow runners are $400-500 and the TB is like $350. You can get a TB that has built in nitrous fitting though that might be useful to you in this app.

    You might consider getting the Vortech fuel injection. 87GMCJImmy runs it and he said his is good to about 5500RPM.

    Harley

    Harley
     
  7. Hossbaby50

    Hossbaby50 3/4 ton status

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    Are you really willing to trust a healthy motor in a 2 bolt block with 150 shot of nitrous though? If you are then you are a much braver man then I. Nitrous is very hard on the bottom end of the motor.

    Harley
     
  8. dyeager535

    dyeager535 1 ton status Premium Member

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    I hope the cost will be worth it to you. Seriously start thinking about how much it's going to cost you to get these heads to do what you want them to do, and see how close it will come to the other heads that come done up the way you need, with thicker castings, etc. Besides the fact you can probably get other heads with larger chambers.

    You may approach $500 on those heads if you do everything necessary to make sure they hold up to your intended usage.

    I had to open up my pushrod slots in the heads to clear my setup, but it sounds like there are some variations in castings, so maybe yours have bigger slots already. My site is down again due to too much traffic, but I have some pics of my vortecs before I installed them, and the pushrod hole is just that, a hole, it's not even slotted.

    I don't know how the newer motors handle it (LT/LS1's, etc) but I had *heard* before that at high RPM's the stock hydraulic roller cam setup has issues. Can't recall what the issues were, but it must have been resolved at some point, everything runs roller now, and you know Corvette engines handle at least 6000RPM.
     
  9. Bullet

    Bullet 1/2 ton status

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    [​IMG]

    EDELBROCK MULTI-PORT FUEL INJECTION /forums/images/graemlins/peace.gif
     
  10. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I agree that a 383 wont want to turn 6K. Why do you want to run nitrous, and so much of it? /forums/images/graemlins/dunno.gif will your Th700 handle it? I know you just went through it but I don't recall you building it up. /forums/images/graemlins/thinking.gif
     
  11. Bullet

    Bullet 1/2 ton status

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    I've had mine in the upwards of 5500 RPM, but I won't push it father than that /forums/images/graemlins/screwy.gif
     
  12. beater_k20

    beater_k20 Banned

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    [ QUOTE ]
    Forged crank if you want it to survive the nitrous. Cast crank if you want to see holes in the oil pan.

    [/ QUOTE ]

    on the contrary my friend. when spraying it, cast crank would be better, and cheaper. the cast cranks will absorb more harmonics than a forged. the cast crank will flex a little, but with too much n2o, the forged crank will shatter unless its a REAL high dollar crank.
     

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