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Max HP out of 454 2 bolt main

Discussion in 'The Garage' started by afroman006, Oct 27, 2002.

  1. afroman006

    afroman006 1/2 ton status

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    My dad is giving me a 454 2 bolt block but it is only complete from the block down. It is originally a carb'd engine (70s era) but since it doesnt have any of the carb parts and I'm gonna have to build it from the ground up anyway, I am going to go with FI. Two questions, where can I get ALL the parts I need to finish the engine (valves, intake manifold, all TBI parts except computer, headers that will fit without cutting frame, and anything else I will need), and how much horsepower and torque can I stroke out of it without having reliability issues because of the 2 bolt main? Thx for the help

    P.S. He has a 4 bolt LS6 kit but that's his
     
  2. nvrenuf

    nvrenuf NONE shall pass! Premium Member

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    I have always read that 2 bolt main blocks (both small block or big block) were good to around 600 hp before they start having problems with holding the crank in. I assume this will be a streetable engine so it only being a 2 bolt main should not be an issue.

    When looking for the parts you will need I would suggest that you start price shopping Jegs and Summit. These are not the only places to shop but they're sales volume does keep them pretty cheap when compared to a lot of small speed shops. Things like heads and brackets are best found at salvage yards or local machine & speed shops, the last 2 usually have a bulletin board where people can post items for sale.
     
  3. willyswanter

    willyswanter 1/2 ton status GMOTM Winner

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    Well, you could always convert the 2 bolt block to a 4 bolt with splayed bolts with the Milodon main caps. Thats what I'm doing to my 78 2 bolt main block, heres a pic:

    [​IMG]

    That pic was taken right before I tightened the mains and started drilling the outer mains. This is actually a stronger setup than stock 4 bolt main blocks due to the splayed outer bolts. Anyway, I have heard 600 hp like stated above is ok on the 2 bolt main blocks. Mine is getting stroked to a 496 and built for around 450hp and 650 ft/lbs of torque
     
  4. afroman006

    afroman006 1/2 ton status

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    Thx man that's awsome. I thought I heard somewher that 400 HP was the cap but I guess not. I'm glad. I think this has been asked before but will the stock computer for a TBI 350 work for a TBI 454? I'm getting giddy just thinkin about it. People know what's up when you say you got a 454... /forums/images/graemlins/thumb.gif
     
  5. bigblock454

    bigblock454 Clack Clack Clack Premium Member

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    HP is only part of the limitation. Probably the biggest factory is what RPM do you plan to run? A 2 bolt 454 could handle just about anything you could throw at it if kept under 5500 rpm.
     
  6. afroman006

    afroman006 1/2 ton status

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    I really doubt I would ever get over 5000 RPM if that. I am always very scared of overreving an engine I dont know why but I always have been. I am planning on installing an aftermarket tach too so I can see what I'm doin. Does it bother anyone else that Chevy didn't put tachs in their 80s model trucks?
     
  7. thatK30guy

    thatK30guy 1 ton status Premium Member

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    /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif /forums/images/graemlins/eek.gif
    /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif /forums/images/graemlins/thumb.gif
     
  8. 4x4Freak

    4x4Freak 1/2 ton status

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    Nope, doesnt bother me a bit.

    Cause I have one!!! /forums/images/graemlins/rotfl.gif
     
  9. Longhorn4x4

    Longhorn4x4 Registered Member

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    I routinely build 454 based engines, with oval port heads, cast cranks, two bolt main blocks, and 3/8" rod bolt rods, to the 700 HP level, at around 7000 RPM. The weakest part of the block is the rear bulkhead, where the rear main bolts on. If you convert a two bolt main block to four bolt main, but do not install a four bolt main rear cap, you have wasted your time. Been there, done that, had the broke junk to prove it before the scrap man hauled it off. If you break a block, the rear bulkhead is where it will break, if the block is the component that fails first. Should the crank break, it COULD break the block anywhere, although we broke a couple after 2000 passes in the bracket engines, and they did not break the block, the block and all but two rods and two pistons were reused. I've been building those things that way for 20 years.
     
  10. willyswanter

    willyswanter 1/2 ton status GMOTM Winner

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    Which is the reason I ordered new front and rear caps too. There on backorder till Dec. 2nd though /forums/images/graemlins/frown.gif
     
  11. afroman006

    afroman006 1/2 ton status

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    Alright badass. Now to the next question. Where can I get the Vortec heads and the right Edelbrock intake manifold for the TBI? Does anyone know of any headers that will go on without having to cut the frame? What size exhaust pipes should I run on a dual system with an X pipe? Thx
     
  12. willyswanter

    willyswanter 1/2 ton status GMOTM Winner

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    The vortec heads you can get straight from any GMPP dealer. Part # 12558060

    That also has the list of the edelbrock and gm manifolds that will work. As for the headers, not sure. For the exhaust, dual 2.5" or single 3".
     
  13. afroman006

    afroman006 1/2 ton status

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    Hey Willys do you know the part number for the BBC Vortec heads? I looked at all the ones listed and didn't see a BBC Vortec set. Am I going to need ALL of those parts to use the heads and if so how much would it cost, total? If I do then they will have to wait for a loonnngggg time to go on... And if so where could I find a normal set of heads for a reasonable price?
     
  14. Longhorn4x4

    Longhorn4x4 Registered Member

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    You do not need, nor do you want, Vortec heads. First off, they have non adjustable valves, second, they do not fit the Mark IV block you have, they leak coolant.

    Either get a set of 049 open chamber oval port heads, or better yet a set of closed chamber 396 oval port heads. The closed chamber head will run better, but needs hardened seats to run unleaded gas. You'll need the 2.19 and 1.88 valves anyway, so don't worry about that. The closed chamber heads yield a full compression ratio higher than the open chamber heads, with flat top pistons. The open chamber head will make 7.8:1 compression with stock flat top pistons, where as the closed chamber heads will make around 9:1 compression. Worth about 50 HP and 50 ft.lb. of torque.

    Go to www.edelbrock.com and check their intake selection. They have several options for fuel injected 454 engines. They have a complete multi port system that replaces a TBI, you only use the throttle body itself.
     
  15. motorheadnelson

    motorheadnelson Registered Member

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    Just built a two bolt for my 73 ragtop. Does it have a forged crank? A two bolt with a good crank, 3/8 ARP rod bolts and main stud kit will take an easy 600 hp, 550+ ft/lbs. Look at the casting seam on the crank throws. If it a fine line, it's cast, which can still handle 500 hp or so. If the parting line is about 1/4 in wide, it's forged. I have the part numbers for the different cranks. Mine was a one ton truck motor, same crank as an LS-6, good rods. You can go as fast as you want to spend with the almighty rat..I've been using Summit Racing Equipment for years, great prices and service
     

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