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Thread: Which block would you run?

  1. #1
    If you had a choice which engine block do you prefer?
    I have a perfect short deck IV Bow Tie block (4.5 inch bore), looking to build a 540 Blower motor.
    Is a Dart or Merlin that much better than the Bow Tie Block?
    Is it worth selling to buy another?

  2. #2
    Bow Tie block is good stuff.
    I would choose the Dart if I did not have any block and had to buy one. The bosses for the extra 4 head bolts are worth their weight in gold. The oiling system is improved over the Gen IV stuff also.
    Wait a minute, I would sell the Bow Tie dirt cheap ( I might need one) and buy the Dart.
    I will haul it off for you.

  3. #3
    I may have someone that is interested in buying the Bowtie Block, but unless I get a good price, I wont sell it.
    Does Chevy still make the IV Bowtie?
    If so, how much are they?

  4. #4
    I don't know if they still make that one or not.
    I have the Gen V Bow Tie in my boat.
    Dart blocks with iron caps are just under 2K

  5. #5
    do you think the dart block (bbc) with iron caps and arp studs will hold 900 hp on nitrous?

  6. #6
    UBFJ #454
    We're running a Big M Dart Tall Deck in a setup designed to put out far more than 1,500 Hp and it has worked well for us ... A couple words of caution though ... And this applies to any block that is going to be used in a 1,000 +/- motor ... Whomever is doing the machine work had better really know their stuff as all mass produced blocks like Dart, Merlin, etc. are really not truly "Race Prep'd" by the manufacturer, even if they say they are. Second thing regarding Darts, if your going to use Large Diameter Lifters like Jesels you need to "Re-Direct" the Priority Oiling System in the "Old Fashion Way" by making mods in the oil routing at the back cam journal ... a good engine builder will know what I mean and how it's done ... If you don't do this #'s 6 & 8 will more than likely starve on start up and you can say "Bye, Bye" to your push rods. Just a couple of comments based on "Been There ... Done That" kinda things.
    The only blocks that I know of that come Truly Race Prep'd are C&N's CNC'd Billet Blocks, but, they're somewhere in the neighborhood of 10K a pop (for AL).

  7. #7
    Agree with Bear big-time, Talk to several machinists before you choose. Speak to some of his other customers. If he won't give you references leave him alone. Your Bow-Tie is a good block but if you intend on running Big boost for a sustained amount of time the Dart is the one. Extra head bolts+big boost= more good.
    just .02

  8. #8
    Originally posted by Infomaniac
    I don't know if they still make that one or not.
    I have the Gen V Bow Tie in my boat.
    Dart blocks with iron caps are just under 2K
    Info, bring me up to speed here. The only siamezed Chevy block I have ever had was the first "green marine" block that had old Mark IV oiling. In the later years, wasn't the Mark IV Bowtie changed to "small block" oiling? Seems to me they did.
    On your Mark V bowtie block, isn't that a one piece rear main seal requiring a different crankshaft? Also do the Mark IV heads go right on or isn't there a different head gasket or something required? What else is really different between Mark IV and Mark V?
    It's well known I make my customers run the best while I run junk.

  9. #9
    I do not know the specifics on the mark IV Bow Tie oiling system
    Yes the Gen V and Gen VI take a 1 piece rear main seal crank. You can use a two piece crank with a seal adapter. They both have Priority main oiling systems along side the cam tunnel
    The Gen VI is made for a roller cam and requires a special cam and cam plate (retainer)The lifter bosses are about .300" taller also.
    The Gen IV heads will go on Gen IV, V And VI. The Gen VI heads only work on gen VI
    No fuel pump boss on a Gen V or VI. The gen V and VI oil pan will not work on gen IV. The IV V and VI all have different timing covers also.
    That is all I can remember. I have a Dart and Gen VI in the shop now.
    Here is My Gen V Bowtie
    Here is the Gen VI HP 500 The stands in the lifter valley are for a "Cage" that holds in the non tie bar roller lifters.
    Here is the seal adapter.
    This is a Gen IV foreground and Dart background. Notice the repair on the deck of the Gen IV

  10. #10
    Thanks Info! You've outdone yourself!
    Block I had was 14044808 tall deck. I found this link which says discontinued. You can see old style oiling system galley.
    Last prices I recall were around $1800. I sure prefer the new oiling system of the new blocks.

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