366 big block?

Discussion in 'High Performance Modifications' started by speedywrench, Aug 21, 2008.

  1. speedywrench

    speedywrench New Member

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    Aug 19, 2008
    Hull, IA
    I was wondering if building a 366 for a 81 z28 is a :dumper: idea or if there are some tips to make it a screamer?

    I'll have pics up soon. I am a new member so here's a quick history.

    Bought the Z with no motor, tranny, etc! It was a mess but the body was good. I built a 350 bored .30 bigger cam, vorteck heads, eldebrock performer intake, eldebrock 650, headers, 5 speed tremec. cragar ss, t-tops,
    Well I got married and needed a motor for a truck and ....... I can't :whine: I parked the car. It's been parked with no motor for over 3 years. Now I have a 350 bare 4 bolt block or this 366.

    Just want some input. What kind of ponies are we talking if I build the 366? How big of a deal is it to drop in?

    Thanks guys
     
  2. Grumpy 427

    Grumpy 427 Veteran Member

    There are many SBC stroker kits out there, the 406 or 415 seem to be making some big power. Depends what you want to do with the car. I have never heard of a 366 BBC? not sure why you would want to build one?
     
  3. speedywrench

    speedywrench New Member

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    Aug 19, 2008
    Hull, IA
    The 366 is out of an old straight truck. The understanding I have is it's the same block as a 454. The stroke is the same the bore is just smaller?!?! That's what I was reading online the other night but I don't know much about them either.
     
  4. GetMore

    GetMore Veteran Member Lifetime Gold Member

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    Nov 8, 2004
    Patterson, NY
    It is not worth it to build a 366 big block. You get the extra weight, and no more displacement.
    If it has the same stroke as a 454 (4.25", IIRC) then it must have a small bore. A small bore means less room for the heads to breathe, and that is not a good thing.
    FWIW, one of the magazines did a test of a 408 small block against a 408 big block. I don't remember the specs, but the SBC was bored 4.165", and the BBC was somewhere around 4.25", and had a shorter stroke to lower the displacement. The BBC made more power due to the larger bore allowing the heads to breathe better.

    Now, if you have it backwards, and it has the same bore as a 454, and there is nothing keeping you from stroking it to 454 or so, then I'd say you may want to go with the big block. I wouldn't do it to my car, but I like handling more than grunt.
     
  5. 74RAT

    74RAT Veteran Member

    3,400
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    Dec 28, 2003
    ft. stockton,tx,usa
    it's a 396/402/427 stroke of 3 3/4" and a very small bore. smaller bore than the 396 @ 4.094,,,,, not really a good starting platform from the 366 block standpoint,, but all the parts you'd put on the outside "could" be transfered over one day.

    just hard to get any compression from it (366) with no performance pistons offered for it. pretty much all the bbc heads require some kind of decent sized dome with any cu. in. size to get compression up to and or over 10.0:1. even the 454 with 100 cc heads will barely get you there with a flat top. just under it anyway.

    you could build up a 427 with that crank if you could find a 427/454 block. can't bore that one to make a 4.250 bore. to thin,, or through to water if you try. you'd have to balance the assy though. it's balanced for the 366 piston weight.

    i think that is also a tall deck truck block if i remember correctly. was used with 4 ring pistons that have a taller compression height/pin height to piston deck.
    3 compression ring grooves and one oil ring groove. calls for the specific tall deck intake,, or using intake manifold spacers. headers can be fun also. they can hit the floor under your feet from the heads sitting up a little taller and raising the header collector flanges. the headers for the tall deck blocks or heads with raised exhaust ports can get pricey. just my opinions. hope it helps.
    andy
     
  6. GetMore

    GetMore Veteran Member Lifetime Gold Member

    2,866
    0
    Nov 8, 2004
    Patterson, NY
    BTW, from how I understand it, the 366 was a decent truck motor. It didn't make a lot of power, but you could stand on the throttle all day and not break it.
     
  7. pdq67

    pdq67 BANNED

    10,496
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    Jul 26, 2001
    Columbia, MO, USA
    It's a TALL DECK BB that has like a 3.935" b x 3.76" s so really can't be made into a larger BB like the bigger bore engines can.

    That and the tall deck block can cause header and aftermarket intake manifold fitment issues so really do your homework if you still want to use one.

    pdq67
     
  8. mrdragster1970

    mrdragster1970 Veteran Member Lifetime Gold Member

    .

    Can't remember the exact specs, but it's a junk block. Can't be bored enough to use decent heads without choking them down. If they were worth anything we would have been using them already all these years. Good luck, listen to the guys, not a good platform to start with.

    .
     
  9. MyBoTy

    MyBoTy Veteran Member

    1,535
    1
    Feb 9, 2002
    Lubbock, Texas USA
    Ge the steel 3.766" stroke crank and snag the 4-bolt main caps and bolts, that's about $200 worth right there to put toward the right engine. Surely you can find a good 2-bolt main 454 block, maybe a cast stock crank and some truck rods. Get lucky and score a pair of open chamber ovals, do a little work on those, pick a cam and have a strong street runner on a budget.
     
  10. rustbucket79

    rustbucket79 Veteran Member

    That's what I was going to say LOL!

    The (2 pc seal cranks) were hard as nails and forged, rods are good HD stock length, main caps of course but aren't a drop on for a 2 bolt block unless they are close enough to only need a line hone, plus drilling and tapping for the outer bolts. The heads actually work well on a flat top 454, giving in the 8.5:1 compression range with their 101 cc chambers. I had a set on my old truck, and took the time to put the pass car 2.06 intake valves rather than the 1.8xx stockers, with a little bowl work they worked quite well. The block is a boat anchor, but probably worth a few bucks at your local recycler.;)
     

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