curious about SBB?????????????

Discussion in 'Small Block Tech' started by CarolinaDrifter, Jan 16, 2013.

  1. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Thanks Jim,it looks like from the 2lb difference bewteen the 2 blocks that the 340 was lightened further than the 300 design,which I kinda thought happened anyway.Thats why Buick increased the main journal size,they used the bigger journal cranks to compensate for the lighter castings they used with the taller decks,just like they did with the 400/430/ 455 block's monster 3.25" main journals,to stabilize the harmonics that a smaller main journal cranks would emit with the thinner castings. Which doesn't seem to be an issue with a 300,but then again it has .450" less stroke than a 340,so?

    If a sbb 340 is made to have a finished wall thickness of .180",and the deck height difference between a 300 and a 340 is .645" then times that by 8 = 5.160" of extra cylinder wall of .180" thick and 3.75" in diameter,that alone should be over the 2 lbs difference between the 2 blocks. Then you subtract the main journal housing bore metal that is removed to house a 3" crank journal vs a 2.50" main journal. Bearing caps about .900" wide X 5 = 4.5" long X 3.188" diameter with a .250" wall thickness. These 2 would probably be close in weight to cancel each other out.Close anyway,BUT,then there is the .645" taller deck comes back into play with the metal surrounding the extra cylinder wall hieght that raises the deck times 2 for both sides should be quite a bit more than 2 lbs with a minimum thickness of .125" to around .188" to hold the coolant in. So weight was taken out in other areas to get the weight down closer to the 300's weight. Unless they just made the outer case thinner to get the weight down?

    In any case,you're probably right,but I can dream until its confirmed can't I?
  2. pmuller9

    pmuller9 Well-Known Member

    As you know the OD of a cylinder wall for a non siamese block is oval with the thinest area between the cylinders.

    With a bore spacing of 4.24 with a 4.00" bore, subtract a .100" space (typical) between the cylinders for water flow
    you end up with a wall thickness of .070" providing there is no core shift.

    Just knock out a freeze plug and measure the space between the cylinders with feeler guages or something similar.

  3. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    Well,if the thrust sides are good(around .150),then a full block fill and an oil cooler,and down the road.:Brow:
  4. DaWildcat

    DaWildcat Platinum Level Contributor

    Personally, I'm very happy to see how the discussion's developed.

    And it doesn't even matter that the original poster hasn't chimed in since his original question!

  5. My66Skylark

    My66Skylark Member

    Gentlemen, I almost hate to disrupt the technical discussion. It is, in fact, very interesting. But I'm a simple guy that happens to have what I believe to be a cool car and I'd like to save it.

    I have no issues getting dirty, but I won't pretend to know how to rebuild an engine. I have a 300 in my '66 Special Deluxe. I'll need to take the vehicle to someone for engine work. Basic questions:
    1) should I cam/port the engine or replace?
    2) approximate cost

    I'm a bit concerned, given some of the comments, that modifying the 300 would be cost prohibitive (I'm not emotionally attached so budget needs to be reasonable). I like the idea of having a "Buick" car, so my preference would be for a Buick engine. Some, however, have suggested replacing with either GM or crate engine. I welcome your feedback.


    WV-MADMAN Well-Known Member

    What exactly is wrong with your 300?

    I for one really like the little 300 and would fight to keep it:TU:

    But by far the cheapest option is to find a running Buick 350.

    The SBB 350 is almost a direct bolt in replacement for the 300.
  7. My66Skylark

    My66Skylark Member

    I haven't taken the car to a shop yet. I was bound and determined to drive it to the shop, not towed. Objective one completed.

    I'm guessing here, but I believe that I have a valve leak. The car sat for quite some time and produced a good bit of smoke once I was able to get it started. The smoke has come down quite a bit, but can get pretty heavy when you step on the gas. If a major overhaul is required, I need to weigh options - repair, modify, or replace.

    I'm not planning on taking the car to the track, but I'd like the car to sound, feel, drive as good as it will look. If the 300 will get me there, I'll stick with it. If it's not a long-term option, then I need to run through my option list, compare costs of each and make a decision. A chorus of folks are saying, "Ditch it and go big." But I'd just as soon spend my own money rather than have them do it. Thus the request for help.


  8. Jim Blackwood

    Jim Blackwood Well-Known Member

    If you can, drive it around for a bit to see if any of the symptoms ease up. Run a compression test. Copy down the numbers. Squirt oil in the cylinder (a couple good squirts) and run the compression test again. Bring the results back here. That will tell a lot.


    WV-MADMAN Well-Known Member

    What color is the smoke?

    That can be a big indicator of what the issues are.

    I agree with Jim that you should drive it some before you deside what your next step is.
  10. Jim Blackwood

    Jim Blackwood Well-Known Member

    Might also run some sea foam or other similar product through it in case you have a stuck ring. Firing on all cylinders?

  11. My66Skylark

    My66Skylark Member

    Just ran the compression test and it looks like I'll be putting a new engine and transmission in the car. One of the cylinders drew a blank (zero) on both the wet and dry test. Most likely a hole in the piston. All others were between 140 and 170. Transmission is also shot.

    I did some investigating and to rebuild the 300 would cost me about $2600 - $3000. A new 350 would run me about $2000. You were correct, again. Transmission another $1500+. Fortunately, I know someone selling a 350 w/transmission for; $1500. It's a 1.5 years old and he's ready to put in a big block. Good news for me. It's a GM, but for 25% of the cost of both engine and trans, my budget says "yes."

    Thanks for the tips. Saved me a lot of time, money and trouble.
  12. 300sbb_overkill

    300sbb_overkill WWG1WGA. MAGA

    For anyone wondering this is a very informative thread, minus the last few posts.

    Big bump!


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