1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

chevy 366 big block

Discussion in 'Chevy Trucks' started by bodhidexter, Sep 8, 2003.

  1. bodhidexter

    bodhidexter Junior Member
    from ma
    Messages: 11

    i have read in a previous discussion that "a 366 big block chevy can only be bored .030 over " is this true, if so why? also can a 4.25 stroke crankshaft be put in this block?
  2. wyldman

    wyldman Member
    Messages: 3,265

    The 366 has thicker main webs,and a taller deck height,but the cylinder walls are the same as any other big block.

    .030" over would be the safe limit.

    Can't tell you if that crank would fit,I don't know on the big blocks.
  3. Rick Loncosky

    Rick Loncosky Senior Member
    from 17557
    Messages: 102

    If you look up the spec's for your 4.25 crank, (out of a 454 right?) you'll find that the mains might be a little bigger. The important thing is the 454's are externally balanced and the 366 are externally balanced. I'm not saying it can't be done but you will have to get the whole rotating assembly balanced or you'll shake it apart.
  4. VictoryRedK1500

    VictoryRedK1500 Member
    Messages: 47

    I was curious what the horsepower and torque ratings were with the stock 366 gas. When I was in school in the 80's and early 90's, most of the county's school bus fleet consisted of Bluebird/Chevy C-60 buses. Currently they run nothing but diesels, Cummins powered Bluebirds.
  5. ratlover

    ratlover PlowSite.com Addict
    from IL
    Messages: 1,325

    366 tall deck block is usefull for 1 thing IMO and that is to rob the steel crank and the steel 4 bolt caps. Well if it is running it makes something deccent to move things around but I wouldnt ever put omoney into one

    a 366 is a 3.76" stroke. just like the 396 402 427 and a tall deck 427 a 454 is a 4" stroke. The mains are the same on all of them.

    I havent ever really heard of anyone stroking a 366. A 4.25 crank would probably go with a bit of clearancing of the block around the pan rails.

    Rick, Do you mean a 454 is internally balanced? It is external. As long as you use a internal ballanced crank/flexplate/balancer or extrenal combo of the 3 you can swap back and forth between the 2 no problem in any chevy motor. If you go to a conventional piston/longer rod from the tall deck stock stuff it will screw the factory ballance up pretty good though.

    A tall deck motor(366 or TD 427) use 3 things that are different from a normal BBC. a different lenght distributor, and extra ringed piston and a different intake.

    Intake can take a special aftermaket or you can use a regular BBC intake with spacers. You can run conventional pistons with a longer rod(pretty common).

    I would generally say it should go 60 over pretty safley but a sonic check would tell for sure.

    I definatly wouldnt put any money into a 366 and never do it as a serious build up even if the block was free. If its a shade tree rebuild on the cheap and all of the parts arnt going to cost much$$$ to reuse then I might throw one back together.

    oh....and the tall deck BBC heads beyond suck.
  6. ratlover

    ratlover PlowSite.com Addict
    from IL
    Messages: 1,325

    and on the power rating.....they make deccent torque but the stock HP is close to a lawn boy

    And before anyone gets all up in arms saying they ran a 366 or a 427 in a dump truck for years and it pulled fine and ran excellent bla bla bla......I'm mostly kidding.....they are ok for thier application. But IMO when it comes to rebuild time its time to canabalize thier crank and main caps. The only thing I can see a 366 block being good at in a truck is in the back as ballast :p A TD427 block might be of some use to a racer that is building TD stroker motor but thats about it. Once they start going south its time to look for a 454 to build. JMO Flame suit one :p
  7. Rick Loncosky

    Rick Loncosky Senior Member
    from 17557
    Messages: 102

    Ya I did a "TYPO", :rolleyes: 454's are EX-ternally balanced and 366/427's are IN-ternally balanced. Thanks I don't want to pass any misinformation.