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New Skool 331 Caddy Build

Discussion in 'The Hokey Ass Message Board' started by c322348, May 20, 2013.

  1. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member


    The head porting is finally done! You can see the numbers in the illustration above.

    The biggest concern was that at .300 lift the intake and exhaust flows were nearly identical. The exhaust flow should be between 75% and 85% of the intake flow according to the "experts." The porting was able to get it to 87.5%.

    The blue line is the actual intake flow, the purple line is the actual exhaust flow. The red and green lines may be confusing, but they show the upper and lower limits of the 75% - 85% range; that's where you want to be. As long as the blue line is in-between the red and green, flow rate is optimal.

    To recap, the engine is a 331 block with an offset ground 390 crank using SBC blower pistons (to get a piston pin height in a useful range). The block was decked .060 to achieve a -.010 deck clearance which will yield a .030 quench height with a .040 thick gasket. Displacement will end up at 399 cubic inches with a 3.910 stroke, 4.030 bore and 7.100 BBC rods (bushed to SBC piston pin diameter with the big-end narrowed to fit the crankshaft journal). All this will result in a 10.7:1 compression ratio.

    The application is a 2600 pound sports car. The power will go through a 3-speed '37 LaSalle top-shift trans and back to a 1950 Ford rear.

    It would have been a lot easier to use a 390 block, but I wanted to use a 1953 331 block like the car was originally built with.

    We've already got a Steve Long custom cam and we're picking out some better than stock valve springs. Final assembly should begin soon!

    I'd like to run the engine on a dyno, but I might need to borrow a better intake manifold. The fabricated manifold I plan to eventually use may be a bit restrictive for this engine.
     
    Last edited: May 10, 2016
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  2. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

  3. falconsprint63
    Joined: May 17, 2007
    Posts: 2,359

    falconsprint63
    Member
    from Mayberry

    so what's the real world build cost on this setup? I'm curious how that compares to a warmed over kit rebuild on a 331/365 or 390. ala asky cam, .030 using stock 390 components SBC valves and lifters etc?

    I will state on the front end this thread is way over my head technically. i'm a body and fab guy. I'm trying to get a simpleton's grasp on cost v benefit here vs a more "standard" type of rebuild.

    I ask mostly because I have a 390 that's going to need to be gone through in the not so distant future.
     
  4. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    I haven't gotten the bill yet and I've had a lot of oddball stuff done- offset crank grinding, balancing, drilling and installing a bushing in the 390 crank for a manual trans, re-bushing and narrowing rods, custom length pushrods, etc.

    Some of my primary goals included forged pistons and forged long rods which has driven much of the cost. I've forgotten now, but with a stock 390 you might be able to find some Pontiac or Olds aftermarket pistons and rods that would be much more affordable to install.

    Refurbishing a stock 331 or 390 is not an inexpensive proposition either. Most jobbers get the parts from Egge Machine.

    The cam was $240 from Steve Long as I recall.

    The only thing I can think of that would make my engine more radical would be a roller cam setup. not sure I quite need that for a street car.

    How much do you think a stock overhaul would cost?
     
  5. falconsprint63
    Joined: May 17, 2007
    Posts: 2,359

    falconsprint63
    Member
    from Mayberry

    when I had my last one built. it was a 365 block stroked with 390 crank and rods, mild custom ground cam from a grinder recommended by another cad guy, sbc 1.94 and 2.02 valves with hydraulic lifters, 390 heads, hardened seats bored .030. I think I was in it for about $4500. not cheap by any standards that's why I was curious how this build compared.

    I bought most of my parts from Kanter and what I didn't was supplied by the NAPA machine shop that did the build. I tried to piece it together to begin with an bought a set of piston off ebay, but two were bad and Kanter sold singles to match. If anyone reading is wondering, you can't use 365 pistons and a 390 rods you have to use the 390 pistons.
     
  6. steinauge
    Joined: Feb 28, 2014
    Posts: 1,507

    steinauge
    Member
    from 1960

    This whole thread is delightful! Can we see a picture of your sports car body ? BTW if you are running a 50 Ford rear do follow through on your statement about not putting much tire on that car .
     
  7. Babyearl
    Joined: May 23, 2008
    Posts: 610

    Babyearl
    Member

    I would like to see the sports car body also,, kind of sparks my interest.
     
  8. Roothawg
    Joined: Mar 14, 2001
    Posts: 19,889

    Roothawg
    Member

    Yeah, I keep hearing cash register sounds in my head as I read this. Not knocking you for doing it, it just makes me pucker a bit. I am a Cadillac virgin, so I read a lot. I just picked up a 62 390 and I am trying to see what I actually need to focus on.
     
  9. cretin
    Joined: Oct 10, 2006
    Posts: 2,866

    cretin
    Member

    I'm definitely interested here. I'll be building a 331 for my Model A roadster build. What year 331 did you start with? I didn't see it if you already mentioned it. I've got a '55.
     
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  10. v8shadow
    Joined: Aug 20, 2016
    Posts: 15

    v8shadow

    Did you have the heads milled? If so, how much?
     
  11. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    No, but milled the block .060 to reduce the quench height between the piston top and the deck surface. Before you do that though consider how your water pump will fit to the heads. I'm not sure the water pump bolts would go into the heads without some kind of surgery. Also, a stock intake manifold may no longer fit well.

    My water pump/coolant system is modified from stock so it didn't matter much to me. I've cut off the thermostat housing from the water pump and will have a custom manifold between the heads.
     
  12. v8shadow
    Joined: Aug 20, 2016
    Posts: 15

    v8shadow

    I am trying to decide my overbore right now. It hasn't been sonic checked yet but I understand that these blocks can be bored to 4" to become a 365 essentially. My 331 is a 54 block.
    Am I reading right when you say you actually bored your 331 out to 4.030"? I am being told I need to be concerned about it running hotter if I go to the 4" bore, yet I read the specs and the cooling capacity for the 365 was actually LESS than the 331. That doesn't make sense to me UNLESS the 365 was a different casting than the 331. I'm also reading on the Cadillac Lasalle club forum that .060 is the maximum overbore for the 331. I just wanted to go with the 4" bore and use 365 pistons. All this isn't making sense to me.
     
    Last edited: Sep 6, 2016
  13. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    Bores are pretty thick on these blocks. I have a '60 SBC 283 bored 1/8" over to 301. That was a common mod back then. The later castings were much thinner. The sonic check will give you the real answer.

    .060 was probably the maximum overbore 331 piston available back in the day.

    I'm far from an expert though. My engine has yet to run!

    P.S. Everyone says get 390 heads if you can for improved breathing.
     
  14. falconsprint63
    Joined: May 17, 2007
    Posts: 2,359

    falconsprint63
    Member
    from Mayberry

    331 and 365 blocks are different castings, but share a lot of parts. the 365 and early 390's are the same block with a different stroke. late 390's add spin on oil filter and supposedly a little better oiling system.

    I had a late 390 block that the machine shop recommended sleeving rather than going .060 on, so I just built the 365 .030 with 390 guts.
     
  15. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    Someone said I wasn't planning on enough carburetor for my build, so now I'm thinking about this: 4 antique eye-talian Weber 45 DCOEs.

    Good idea or bad? New, yet old...
     

    Attached Files:

  16. Roothawg
    Joined: Mar 14, 2001
    Posts: 19,889

    Roothawg
    Member

  17. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    This car has a low hood-line, so the intake manifold design is a challenge. Working on it! :)
     
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  18. Terry Buffum
    Joined: Mar 20, 2008
    Posts: 277

    Terry Buffum
    ALLIANCE MEMBER
    from Oregon

    You mentioned "The application is a 2600 pound sports car. The power will go through a 3-speed '37 LaSalle top-shift trans and back to a 1950 Ford rear."

    Any chance we'll see you at the vintage sports car race at Laguna Seca in August? Our pit generally has the four cars in my avatar, now plus a Kurtis. Please come out and play!
     
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  19. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    I'd love to! I've been meaning to go for 20 years now and never made it a priority. I should!

    In case you haven't seen my album on the car:

    http://www.jalopyjournal.com/forum/media/albums/richards-special.26850/
     
  20. Terry Buffum
    Joined: Mar 20, 2008
    Posts: 277

    Terry Buffum
    ALLIANCE MEMBER
    from Oregon

    I love your car! I used to have the same body Allied fiberglass Cisitalia 202D (mold pulled off of Robert Peterson's car while it was in the Barris shop for paint, as I'm sure you know) on a tube chassis on t-bars. It originally had half a Duesy engine, later a flat head. I sold it before I retired to Oregon.

    Even if you're not ready to race this year, please do come by our pit and visit!
     
  21. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    Will do! I remember the article Geoff Hacker wrote about it.
     
  22. Terry Buffum
    Joined: Mar 20, 2008
    Posts: 277

    Terry Buffum
    ALLIANCE MEMBER
    from Oregon

    Your four 45DCOEs should be plenty of carburation, and they will look and work great! I have three on the Jag (only about 240 cubic inches) making around 300 hp. Rob runs three on his 12 port GMC (320 cu in) making about 350.
     
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  23. boo
    Joined: Jul 6, 2005
    Posts: 545

    boo
    Member
    from stuart,fl.

    i'm putting a 1955 331 stock, 48,000 mi eng in my 34 rdst, using a 3-2 intake w/3 #97's, just a cruiser, any prob w/progressive linkage to run one carb w/cruising???
     
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  24. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    Stock 390 tripower made 345 I think. Hoping to make 400 or better. We'll see!


    Sent from my iPad using The H.A.M.B. mobile app
     
  25. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

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  26. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    [​IMG]Mallory metal needs to balance crank. Forged Ross pistons are so much lighter than stock cast Caddy units.


    Sent from my iPhone using The H.A.M.B. mobile app
     
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  27. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

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  28. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    [​IMG]BBC rods and narrow bearings had to be narrowed further to fit reduced width Caddy journal. Crank was offset ground with a generous fillet radius.


    Sent from my iPhone using The H.A.M.B. mobile app
     
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  29. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    [​IMG]Deck was cut to allow pistons to end up .020 below deck. With a deck cut like this, the water pump ports in the head may not line up. I'm running an odd water pump configuration so this doesn't matter to me.


    Sent from my iPhone using The H.A.M.B. mobile app
     
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  30. c322348
    Joined: Nov 28, 2007
    Posts: 312

    c322348
    Member

    [​IMG]New gear set and custom ground hydraulic cam go in next. The short-block is nearly complete. The engine builder will need to find some valve springs that will fit the head and support 6500 RPM.


    Sent from my iPhone using The H.A.M.B. mobile app
     
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