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Help with 73 340 build

Performance Upgrades

  1. 40sloop

    40sloop New Member

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    Hudson County, NJ
    Looking to bring a 73 340 to about 400 hp. This engine will be put into a 73 Cuda with a 727 and 3.23 8 3/4 rear end. Block was machined already. I’m not looking to daily the car. Only driven on warm summer days on the weekends. Kind of a street/strip use. I am aware everything needs to be balanced. Though I am new at this and am reaching out for help.

    Already purchased
    Speed pro l2316f pistons bored .30 over.

    Should I keep my original heads and what should I do with them if I do? Port? Bring intake to 2.02?

    What cam? Preferably a lopey idle

    For some reason, the crank is forged odd for a 73

    Looking to use stock rods, new bolts?

    intake?

    Headers?

    Already have 650 carb will upgrade to 750 if needed.

    Ignition?

    Sorry if the list is too specific just what I have and know about currently. Thanks
     
    Last edited: May 13, 2019
  2. hellrats

    hellrats Well-Known Member

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    Your pistons, good choice
    Your heads are ok too. Just clean up the bowls and put in 2.02 valves. Gasket match the ports don't go crazy.
    Cam Voodoo Hydraulic Flat Tappet Cam & Lifter Kit - Chrysler 273-360 268/276 - Lunati Power you'll love it :) Ask your machinist to pick the springs and set them up. Lunati runs way too much seat pressure if you ask me. You may have to cut the valve guides down also... it may be close.
    Crank and stock rods will be fine. They are both tough factory parts. Have them magnafluxed. Rods resized and new bolts. Your balance will be very close. The Speed Pros are replacement pistons. So it would not cost much to have it checked.
    Edelbrock LD340 intake would be my pick. You can find them used for a good price if you look around.
    I use the factory Mopar electronic distributor with an HEI module. Read this Mopar HEI Conversion. It will tell you how to hook it up and it's very easy. Plus you keep the correct advance curve you need for you engine. The bracket he sells is very nice. I have used it many times. A 650 will feed a 340 all it can use and be very drivable. You will want at least 2400 stall convertor with this cam. If you have a stock 340 convertor it should already be already be about that. Headers are always a better performance choice but the stock manifolds are not bad either plus they don't set low and get caught on everything. If you get headers DO NOT buy cheap ones!
     
    Last edited: May 14, 2019 at 11:02 AM
  3. aussiemark

    aussiemark Well-Known Member

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    I bought new Scat I beam rods they were reasonably priced stronger and lighter then the original ones by the time you've bought good rod bolts and paid to have them resized, crack tested and small end bushes replaced they will cost similar but not be as good. I went for KB hyperutectic pistons, TRW's are now made in India and not as well as the old US made ones, if I was using a forged piston I would go with Arias or JE made in the US, lighter and better quality for not much extra cost.
     
    Last edited: May 14, 2019 at 5:36 AM
  4. hellrats

    hellrats Well-Known Member

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    Speed Pro pistons are forged in India and finished in the USA. KB are good pistons but his compression maybe too much for a street engine. Plus he already has the Speed Pro pistons and there is nothing wrong with the OEM rods. I just had a set resized and SPS bolts put in and it was 150 buck. I have raced them for years and never had a problem. Hell we used to use the old light 273 rods in circle track engines to save weight. But to each his own as they say.
     
    Last edited: May 14, 2019 at 11:03 AM
  5. 40sloop

    40sloop New Member

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    I do like the vodoo cam but will it get me to the preferred power range? I'm also quite focused on what to do on the heads. If I just clean the bowls and port them will it be enough? Also, where would I get the 2.02 valves from.
     
  6. hellrats

    hellrats Well-Known Member

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    That cam will pull hard all the way to 5500 RPM and still be drivable on the street. Plus it will still have enough vacuum if your running power brakes. You can ordered valves from any auto parts store or online. Just look up valves for a 1970 340 as they all came with 2.02 valves. Look at your keepers because there are 2 and 4 groove locks so you get the correct ones.
     
    Last edited: May 14, 2019 at 11:05 AM
  7. moparleo

    moparleo Well-Known Member

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    Everything depends on your budget. If you can do it, a new set of aftermarket heads would be the way to go. To get a 45 year old set of heads cleaned, magnafluxed, surfaced, new valves, guides, seals, springs, keepers and any bowl work as well as hardened valve seats, a set of new heads is very reasonable and would be more durable.
    If you are not prejudiced about brands, there is Indy, Edelbrock, Engine Quest, Mopar, and others.
     
    • Agree Agree x 1
  8. hellrats

    hellrats Well-Known Member

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    No aftermarket head is ready to bolt on and go. Everyone I have ever had I had to change the springs to the correct ones for the cam. Most don't have the correct shim under the springs in the seat pocket. Plus you still need to match the ports. They will let you get away with a bit more compression though. If his heads are correct for a 1973 they will already have hardened seats installed.
     
  9. aussiemark

    aussiemark Well-Known Member

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    New heads are a good idea they will flow better then the old ones and it's always good to have them checked out before you bolt them on. If you choose Aluminium heads you can get some weight off the top of the engine and run higher compression. I bought some Mopar Performance Aluminium heads for my 440 and they flow better then radically ported stock heads straight out of the box and the ports are actually smaller then the ported stock heads so the low rpm air speed is faster. If I ever decide I need more I can get it, what can you do if you want more from modified stock heads? nothing it's like the old saying your better off with the crappy house in the nicest suburb then the nicest house in the crappy suburb.