427 tall deck

Discussion in 'Engine: Repairs , Modifications ,trouble shooting ' started by JMck64, Mar 26, 2019.

  1. JMck64

    JMck64 Member

    I recently found a 427 tall deck motor. Its a .030 bore with standard bearings on both mains and rod journals.
    I found two ways of building this motor, stroker kit for a 496, or a 427 car motor.
    I also have two pair of BBC heads, Rectangular port (3994026) open chamber with 2.19 int. 1.88 exh. and Oval port (3872702) closed chamber 2.06 int. 1.72 exh., but both are bare. Looking for the most economical builds for both, the 454 block is .030 over and if I purchase the stroker kit for the 496, I can use the internals from the 427 TD, and install 427 crank into the 454. Which would give me a 427 car block and a 496 stroker engine. I am looking for some ideas on these motors, any more info?
  2. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    welcome to the forum
    have a local machine shop carefully inspect the existing crank and rods ,
    before you use them to build a 427 in a short deck/standard block
    Id certainly have the rod bolts in the truck rods swapped for new ARP, rod bolts.
    try to select a 6.385" connecting rod and 7/16" rod bolt rotating assembly,
    for the 489 stroker

    scat cast steel cranks tend to be better quality and more precisely machined,
    than most other rotating assemblies from what I see.
    given youll be using the two sets of existing heads you now have on two builds,
    one a 489 stroker and a future 427,
    the larger valve ,open chamber heads with a dual plane intake,
    would certainly be my choice,
    on a 489, stroker, the smaller oval ports are a better match to the 427 build,
    obviously you'll need new pistons in the standard deck block and re-balancing the rotating assembly.
    the oval ports may provide a bit more lower rpm torque, but the valves and closed chamber head design,
    will be comparatively restrictive in the mid and upper rpms, be sure you select pistons ,
    that get the static compression up in the 9:1-9.7:1 range if you use pump gas.

    bore diam x bore diam. x stroke length x # cylinders x .7854= displacement








    Last edited: Mar 26, 2019
  3. Unforgiven

    Unforgiven Well-Known Member

    Welcome to the forum from Michigan!
    I am looking forward to seeing this build.
  4. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    a few related and useful threads,
    for many people,
    reading through the links and sub links,
    will look like extra time and work that might best be ignored,
    but it will eventually cost you time and cash,
    if you don,t have the info the links contain.

    the tall deck BBC is a very good place to start,
    if your thinking of building a 489-496 stroker big block chevy,
    performance engine
















    Last edited: Apr 11, 2019
  5. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    496 Stroker Works !
    Proven on Grumps last year.
  6. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    Tall Deck 427 is strongest Factory GM Block along side 455 Pontiac.
  7. JMck64

    JMck64 Member

    Thank you for the info. Last night I was plastic gauging the crankshaft, the bearings were STD. on both, but after the plastic gauge on the mains, 1).002 2).002 3).0015 4).0015 5).002 so I now need to have the crankshaft turned, I stopped there, so I am starting with .010 / .010 for the Mains and Journals, this engine also had the larger 427 pistons .030, brand new by the looks of it, so I will try to sell this 4 ring piston .030 for some cash. I will get the number to these pistons. But I will check your threads here tonight, again thank you
    Last edited by a moderator: Mar 27, 2019
  8. JMck64

    JMck64 Member

    Thank you so am I lol
  9. JMck64

    JMck64 Member

    Well I guess that late night post was off a bit, the crankshaft is within specs, the pistons that I have appear to be aluminum .030 427 tall deck truck pistons, any info here? What's a good cam for this motor is left stock or as is?
  10. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    Grumpy does not like the 4-ring pistons.
    I have a 427 Tall Deck too put away.
    Good shape. Blocks are not date coded on Tall Decks any year I have found.
    Heads on it are Tall Deck 427 Oval ports.
    Similar to the desirable 781's. 1984 casting date codes.

    Cam was mild.
    Only has 230 Hp most tall decks.
    It may be more because in trucks they all had a Governor carb Holley 4bbl that limited cfm to only 300-400 cfm.

    270 -280 advertised duration be a start.
    Pistons stock are heavy.
    But drop forged aluminum.
    Last edited: Mar 28, 2019
  11. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    Been about 1 year.
    I was going to do the same just roll new bearings in. New oil pump.
    New Cloyes True Roller Timing chain set.
    Isky Mega Hydraulic 280 cam.
    Tall Deck Moroso Intake spacers.
    Modern Brodie race oval port intake.
    Install into my 1987 Corvette convertible.
    Backed by a TH400 trans fab my own trans Crossmember using drag tech fabrication.
    I listened to Grumpy.
    I will buzz it high.
    6500 +.
    Shelved project for now.
    496 ci Stroker better. Proven so here .

    Decided to put my Old 70 T/A back together in 2019.
  12. Maniacmechanic1

    Maniacmechanic1 solid fixture here in the forum

    It's a solid $5,000-$15k build project 496 depending upon power level.

    Been told by other Chevy guys 454 better on a tight budget.
  13. JMck64

    JMck64 Member

    I just found out the parts for the 427 as in gaskets are not listed in parts stores, is it safe to assume that they different than 454 due to the 5/8 inch tallet and longer? And where's the best place to buy?
  14. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    almost all the gaskets in a tall deck BBC interchange with a standard deck engine gaskets.
    the intake manifold is wider the distributor needs to be the slip collar style to match the distributor intake to cam clearance correctly,
    and if you choose to use the standard deck intake manifold youll need spacers on the tall deck.


    Last edited: Apr 10, 2019
  15. JMck64

    JMck64 Member

    One more it I am looking for, intake manifold spacers for oval port applications. Is there one available?
  16. JMck64

    JMck64 Member

    With that in mind, using the Edelbrock performer dual plane manifold. What camshaft and lifter combo would you suggest? I'm using the closed chambered heads with smaller valves on the 427 TD, 1970 To 1973 peanut port heads. The range for performance is 1500 to 6500 rpm's, the heads appear to be stock, but I am looking to keep the lift down so I won't have to more machine work done. We have decided to keep the 427 TD as semi stock motor, and I will purchase a SCAT assembly for my 489 or 496 build.
  17. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

    flat tappet?
    solid or hydraulic?
    and whats your static compression.
    what transmission,?
    what cylinder heads will you use?
    if automatic what stall converter?
    truck/car rear gear ratio?
    ,and intended use?
    do you have headers?
    Last edited: Apr 11, 2019
  18. JMck64

    JMck64 Member

    Flat tappet- just more lift.
    The pistons are the 427, 4 ring, but .030 flat tops, unsure of static compression, but the pistons are
    Sealed Power L2377F30 Engine Piston
  19. JMck64

    JMck64 Member

    Forgot to add, 77 Chevy van with 2.73's right now and a turbo 350 trans. Looking to put a 700R4 trans.
    Strange but that's my project for dad, he just went thru surgery and he lost his right leg.
  20. Grumpy

    Grumpy The Grumpy Grease Monkey mechanical engineer. Staff Member

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