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Best 7.3 idi build.

Discussion in '6.9L IH & 7.3L IDI Diesels' started by steve07spirit, Apr 3, 2020.

  1. steve07spirit

    steve07spirit Registered User

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    Hey all, I hope everyone is well during these trying times. I would like to build the very best 7.3 idi that I can. I have an engine to start with which came out of a 93 f350 n/a but yet has all the turbo internals. Here is what I propose, list all the weakness of this motor and address, or better yet upgrade them. Commentors start dreaming , i plan on taking all the best options.
     
    Enginerd likes this.
  2. Randy Bush

    Randy Bush Full Access Member

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    First to do is find a turbo block, stronger then a NA one.
     
  3. steve07spirit

    steve07spirit Registered User

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    Hey randy this is a turbo block and internals but was run N/A.
     
  4. IDIBRONCO

    IDIBRONCO IDIBRONCO

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    Ask Wes to give you his list. Then you'll have the best build that you can have.:Thumbs Up
     
  5. Garbage_Mechan

    Garbage_Mechan Garbage Mechanic

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    One thing for sure:
    You can have all the best parts in the world but if you don’t have a competent machinist you have nothing but misery.
    If you don’t have a relationship with a machine shop, be sure to do your research carefully. Engine machine work is a shrinking field.
     
  6. Booyah45828

    Booyah45828 Full Access Member

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    I could not agree with this more. Good machine work can make or break any build. And rebuilding an engine isn't something you want to have to do more then once.
     
  7. lotzagoodstuff

    lotzagoodstuff Supporting Member Supporting Member

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    I think finding a competent machine shop to build IDI stuff shaves an already small number down even further. My suggestion is asking the open ended question of "how familiar are you with pre-cups and how do you determine if they've been installed properly?" If the shop isn't familiar with the pre-cup design, you'd better consider another shop or maybe just be prepared to walk them through everything and watch them like a hawk. Simple things that are common in gassers like decking a cylinder head can become much more complicated (spelled detrimental) on an IDI.

    Good luck: properly built IDI's seem to last quite a while.
     
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  8. Jason1377

    Jason1377 Supporting Member Supporting Member

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    If all else fails I am sure @Thewespaul or any other great shop on this forum would be more the happy to rebuild a motor for you have seen nothing but great things from these fine folks.
     
  9. Blackascoal

    Blackascoal Registered User

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    You want to have Wes at Classic Diesel Design rebuild it. R and D also rebuilds them. I see your in Arkansas. Wes is in San Antonio, TX.


    Sent from my iPhone using Tapatalk
     
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  10. rhkcommander

    rhkcommander Full Access Member

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    The bottom end is stout. The top end flows well but a new cam will help. Dont really need any head work, they flow better than PSD heads.

    The head bolts or studs are a weak point, the heads will lift above 10 or 12 psi in short order. Recently Wes or somebody floated the idea that 7.3 head gaskets were stronger than the 6.9 because of the filled coolant channel.

    Soot getting in the oil can bother some, you can set these up for longer oil life with bypass filtration, and run bigger oil filters. Rebuild the oil cooler, they love to leak after a while.

    Fuel was always the limiting factor for power on these, other than head lifting issues. Conestoga, R&D, and CDD all do bigger pumps. 80CC is about stock, 2.2 hp per cc to the wheels is a decent rule of thumb, so buy accordingly. You might need an electric lift pump, if your engine ever loses prime or you have fuel leak down issues the mechanical lift pump will drive you nuts.

    Add a nice intercooler and make a custom intake for better flow, and get a 3 inch dow pipe and run 3-4" exhaust after that.

    The old radiators are OK if you find a solid one. Otherwise you can get a cheap 3 or 4 row on ebay, or sacrifice your next child for a rodney red aluminum radiator.
     
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  11. IDIoit

    IDIoit MachinistFabricator Supporting Member

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    the very best IDI, will need 2300 in connecting rods, and then 700-ish to modify ;)
    not to mention the decompressioning, and coating, and total seal 2nd fire ring.

    promar's long block run about 3500$

    145.jpg
     
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  12. Booyah45828

    Booyah45828 Full Access Member

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    Do you see a reduction of soot in the oil with the gapless 2nd ring?
     
  13. Thewespaul

    Thewespaul Supporting Vendor Supporting Member

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    Thanks for all the recommendations, if you have any questions about your projects let me know! FYI... Stock pumps are actually calibrated to 67cc peak and 58cc at hp peak, so even an 80cc pump is a good upgrade from stock.
     
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  14. rhkcommander

    rhkcommander Full Access Member

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    Gotcha, thanks for the clarification. The older I get the more I forget!

    Another popular upgrade is 921 valve springs, stiffer than stock.

    Everything everyones said covers most of the engine upgrades that I can recall.
     
    Dane Rickford likes this.
  15. typ4

    typ4 Supporting Member Supporting Member

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    Not true
    Ive measured all the things that are supposed to be different, oil galleys are about it.

    I have 15 years and 100k + on my engine build. If you want reliability and good torque and power pm me.

    Same pump and injectors FYI, needs injectors now. But thats about it.
    It just made a 4500 mile round trip to WI at about 85-90 everywhere I could.
    Added no oil.
     
    Last edited: Apr 6, 2020
    Macrobb, hacked89, Jason1377 and 4 others like this.

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