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  1. #1
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    Default What year Big Block Buick to Build?

    If you are questioning what year motor to start with for your big block Buick (BBB) build-up, this thread is for you. (If you are looking for a ’70 SF motor to build “because it has 370 HP,” you REALLY need to read this thread!)

    I’ll cut to the chase and give you the answer right off. With one major exception, it really does not matter. The exception is the 75-76 heads. They are junk, due to their compression-killing open combustion chambers. Everything else is 95% comparable between every BBB ever made.

    If you are concerned about factory horsepower levels, the fact is that the iron “hard parts” (block, crank, rods, heads, and manifolds—the stuff you might re-use in a rebuild) of a BBB have very, very little to do with the power output of the engine. Now, as Paul Harvey would say, here is the rest of the story…

    Crank and rods
    All BBB cranks and rods are identical, equal, and interchangeable.

    Blocks
    1967 through early 71 blocks have a smaller oil pick-up passage. This is easily drilled out during machine work. 75-76 blocks are slightly heavier (about 10 lbs.) For anything under 500HP, this is just dead weight. And there is only a small horsepower window between where using a 75-76 block would be beneficial before you get to the point where you need a girdle no matter what.
    If they pass a sonic check, 400-430 blocks CAN be bored out to 455, but you better send your machinist a Christmas card after that.

    Heads
    As stated, 75-6 heads are junk, due to the open combustion chambers. For the drop in compression between 70 and 71, most of the change was done through a deeper dished piston. The 71-74 heads have slightly larger combustion chambers, but not by much. They flow just a well as earlier heads. The emissions passages in 72-up heads do not affect flow. 67 and early-68 heads are known as “big port heads,” due to slightly larger intake passages. Untouched, they do flow a little better than later heads, but if you are doing any porting, it is just a “head start” for the porter. Any port job will go way beyond the flow of big port heads.
    Stage 1 heads are just the same castings as regular heads of that year with larger valves installed. Any BBB head can become a “Stage 1 head.”
    67-69 BBBs oiled the valve train through oil passages in the block and heads, into the rocker shafts. 70-up oiled through the pushrods. You can use through-the-pushrod oiling on any BBB, but, 455 blocks continued to have this oil passage in the driver’s side of the block. So, if using early (67-9) heads on a 70-up block you need to block this oil passage, either in the block deck, or in the head. The passage is in the front rocker shaft pedestal, right next to the rocker shaft bolt hole.

    Manifolds
    All intake manifolds will flow equally. As with the heads, any emissions passages added to later intakes do not affect flow. If you are putting a 67-71 intake on later heads, you need to block the AIR passages at each corner of each head, as the earlier intakes don’t cover them. There are also issues with the exhaust crossover changing in, I believe, 72. Some (all?) 67 intakes do not have the cast-in bosses to mount the throttle cable bracket.
    67-69 heads use 3/8” intake bolts and 70-up use 7/16” bolts. Obviously, you use whatever bolts fit the heads. The bigger bolts go through the bolt holes in the earlier intakes just fine.
    All exhaust manifolds flow equally. Some 67 manifolds do flow a little better, but not a big difference.

    If I missed anything, or others have a different take on any of this, chime in!
    Last edited by Nicholas Sloop; 10-25-2007 at 02:51 PM. Reason: more accurate info

  2. #2
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    Default Re: What year Big Block Buick to Build?

    Nicely done, Nicholas!

    Devon
    Fuel & Brake Systems Engineer
    "I can live with doubt and uncertainty and not knowing. I think it's much more interesting to live not knowing than to have answers which might be wrong." - Feynman
    "Good data is precious. The problem I have is when some damned fool fails to use it properly." - Slingerland

  3. #3
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    victoria B.C. canada
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    Default Re: What year Big Block Buick to Build?

    is that 50 lbs heavier a typo
    Adam
    victoria B.C.
    69 GS 400 street strip
    Stage3 heads,Gforce 4 speed,12bolt
    -PUMP GAS 464 9.98 135-
    3600 pounds

  4. #4
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    Default Re: What year Big Block Buick to Build?

    nick


    One of the biggest reason for useing a 75-76 block for us in high HP builds is lifter bore mateial the bores in MOST 75-6 blocks can be well over twice as thick. I broke a lifter bore in a 70 block 10 years ago and the bottom of the bore was less than .100 thick. I agree with the main girdle part but if you plan to be agressive at all with your cam whether it is a flat tappet or roller or if you plan to add a ta lifter girdle its better to start with good lifter bores.
    Bobb Makley
    70 Stage 2 Street eliminator 9.80's @136 R.I.P
    72 stage 2 3750 LBS
    Pro charged bulldog block
    8.80's @153+w/ 1.34 60
    85 pro Street regal
    10.40's @ 128

  5. #5
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    Default Re: What year Big Block Buick to Build?

    Outstanding thread.....very well done.....
    Chris Jones

    73 Riviera (in progress)
    97 GMC Suburban
    2000 Nissan Altima

  6. #6
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    Default Re: What year Big Block Buick to Build?

    Nick,
    Nicely done. This should be a sticky in the FAQ forum, like my timing thread.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  7. #7
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    San Antonio, Texas
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    14

    Question Re: What year Big Block Buick to Build?

    so if I'm reading this correcltly..

    you would probably want to use a later model block, with either stock or moddified 67-74 heads. 75+ heads have too large of a combustion chamber?

    what if you had 75+ up heads, is there anyway to "close" the chamber by running domed piston or is there a valve clearance issue there?

    Just curious since I haven't gotten to go pickup or see my 455 yet.. already planning my rebuild
    =======================================
    I live my life one paycheck at a time, for those 9 seconds after I get my check cashed... I'm rich...

  8. #8
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    Default Re: What year Big Block Buick to Build?

    I do not have a 75/76 455 but the 70 & 71 block I have seem to have decent material for the lifter bores. Nice and even too. Same for the cylinders.
    I also have a 72 block with a few extremely thin bores (way under .100") and core shift. Even some the cyl. walls are real thin only on the one side of the cyl..
    If I was looking for a block I would pull the pan and intake to have a look at how much meat there is for the lifters and cyl. and check out how even it was cast regardless of the year just to be safe. I've worked in 2 foundries for 12 years. Cast iron and aluminum. Alot of things can happen.
    Ray

  9. #9
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    Default Re: What year Big Block Buick to Build?

    75+ heads have too large of a combustion chamber?

    yes, but the bigger problem is that they have absolutely no quench / squish area. that's why they're called 'open'.

  10. #10
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    Default Re: What year Big Block Buick to Build?

    Quote Originally Posted by LARRY70GS View Post
    Nick,
    Nicely done. This should be a sticky in the FAQ forum, like my timing thread.
    Thanks, Larry. That was the whole point. I PM'd Jim W. to ask him to make it a sticky, referrencing your timing thread, and he said sure, but put in in the FAQ section. I will put my original post there, but I'm not sure if I can move the whole thread...

  11. #11
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    Default Re: What year Big Block Buick to Build?

    Quote Originally Posted by NSAN1T View Post
    so if I'm reading this correcltly..

    you would probably want to use a later model block, with either stock or moddified 67-74 heads. 75+ heads have too large of a combustion chamber?

    what if you had 75+ up heads, is there anyway to "close" the chamber by running domed piston or is there a valve clearance issue there?

    Just curious since I haven't gotten to go pickup or see my 455 yet.. already planning my rebuild
    You are reading correclty. There is no way to "fix" 75-6 heads. There are no domed pistons for Buicks. Only flat-tops, which can get you serious compression with good heads, and deck and head milling. The block issue is pretty much a non-issue. Unless you are in the high horsepower range, or running a big cam (see Bobb's post above), the later block is really not an issue.

  12. #12
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    Default Re: What year Big Block Buick to Build?

    Quote Originally Posted by bobkmando View Post
    75+ heads have too large of a combustion chamber?

    yes, but the bigger problem is that they have absolutely no quench / squish area. that's why they're called 'open'.
    I think we are saying the same thing here, just using different words...

  13. #13
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    Default Re: What year Big Block Buick to Build?

    Quote Originally Posted by Nicholas Sloop View Post
    Thanks, Larry. That was the whole point. I PM'd Jim W. to ask him to make it a sticky, referrencing your timing thread, and he said sure, but put in in the FAQ section. I will put my original post there, but I'm not sure if I can move the whole thread...


    Nick,
    Any of the moderators can move the entire thread and make it a sticky for you. Just PM one. It should be in the frequently asked questions (FAQ) Any time someone asks the question, just link them to your post. That's what i do with Timing questions.
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  14. #14
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    Default Re: What year Big Block Buick to Build?

    Quote Originally Posted by LARRY70GS View Post
    Any time someone asks the question, just link them to your post. That's what i do with Timing questions.
    Me too, unless you beat me to it...

  15. #15
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    Default Re: What year Big Block Buick to Build?

    Quote Originally Posted by standup 69 View Post
    is that 50 lbs heavier a typo
    No, not a typo.

  16. #16
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    Default Just a note..

    Always sonic check a 455 block--- always..

    Don't assume because it has no visible core shift, or because it is a certain year block, it's good for a high HP build..

    I have a number of sonic sheets from 76 standard bore 455 blocks, that look perfect in the lifter valley, but have core shift in the passenger side bank, particularly bad on the backside of number 4 and 6 hole, in line with the pin.

    That said, I also have a couple '76 race blocks that were over .200 everywhere, and that is super for a 455 production block.

    Moral of the story.. sonic check-- always.. it's the best 40-75 bucks you can spend, and it should be done before anything else is attempted.

    JW
    Owner/operator

    Tri-Shield Performance
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  17. #17
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    Default Re: Just a note..

    Useful Casting numbers for various year Buick 350 and 455 engines

    http://www.v8buick.com/attachment.ph...9&d=1171504079
    Larry
    1998 "Fully Optioned" SC3800 Riviera
    70 GS 455 Stage1, TSP 470, 602 HP@ 5900, 589 TQ @ 4900
    TA Hyd Roller Cam, 230*/238*, 112, .544"/.577" lift, 4-7 swap
    MSD Digital 6+, Ignitionman Distributor w/MSD trigger
    THM400 with Ultimate 258mm converter, Gear Vendors OD
    AED 1000 HO Carb, 800 CFM 7042240 Quadrajet
    8.5 10 bolt, 3.73's Race weight 4025lbs.
    Best E.T. 11.54 Best MPH, 116.06
    Larrymta@verizon.net, GSCA #291
    BPG # 1063
    N.E. GS/GN Club Assistant Director

  18. #18
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    Default Re: What year Big Block Buick to Build?

    This is a very nice sticky.

    I have one question about the oiling schemes on the different blocks/heads. I'm planning on using 1970 455 heads on a 1969 400 Block....problem or no problem?
    So will that work fine or do I have to mod something slightly?

    Thanks In Advance.
    Ian
    1949 Chevy Styleline Deluxe
    1967 Buick Special Wagon - 400BBB/TH350
    2000 Pontiac Trans Am WS6 6 Speed
    2000 Chevy S10

  19. #19
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    Default Re: What year Big Block Buick to Build?

    Quote Originally Posted by htwhls19 View Post
    This is a very nice sticky.

    I have one question about the oiling schemes on the different blocks/heads. I'm planning on using 1970 455 heads on a 1969 400 Block....problem or no problem?
    So will that work fine or do I have to mod something slightly?

    Thanks In Advance.
    Will work fine. Just use 70-up lifters, pushrods and rockers.

  20. #20
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    Default Re: What year Big Block Buick to Build?

    I would suggest blocking the oil feed holes in the deck that used to oil the old-style rockers, rather than relying on the head gaskets to seal them up.

    Devon
    Last edited by DaWildcat; 11-04-2007 at 10:44 PM.
    Fuel & Brake Systems Engineer
    "I can live with doubt and uncertainty and not knowing. I think it's much more interesting to live not knowing than to have answers which might be wrong." - Feynman
    "Good data is precious. The problem I have is when some damned fool fails to use it properly." - Slingerland

  21. #21
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    Default Re: What year Big Block Buick to Build?

    Quote Originally Posted by DaWildcat View Post
    I would suggest blocking the oil feed holes in the deck that used to oil the old-style rockers, rather than relying on the head gaskets to sel them up.

    Devon
    I thought about suggesting that, but every 70-up 455 still has the passage on the driver's side, and I've only heard of one instance where someone suggested that oil was seeping out through the head gasket (and I am skeptical of that).

  22. #22
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    Default Re: What year Big Block Buick to Build?

    Ok, I have a question then. I have a 75 block with 73 heads. I know its lower compression because of the piston dish. What spec pistons would I have to put in to raise the compression to 10:1 or so. Also does this lower compression really affect my perfomance that much.
    65 Special, now a 455!
    Had a 61 skylark shell
    70 Skylark 350 Driver, with lightening holes!

  23. #23
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    Default Re: What year Big Block Buick to Build?

    Hmmm are the 75 heads "really" pieces of crap.
    Can't they be used in a boosted car. Turbo/compressor setup, due to the low compression??

    I have a couple of them heads. Dont know what to do with them though.......anchors maybe

    // Jan
    Last edited by SwedishGS455-71; 08-22-2007 at 03:37 PM.
    Jan Havman
    Sweden
    1971 GS 455 Ht

  24. #24
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    Default Re: What year Big Block Buick to Build?

    Unless I missed it in this thread, what about having the '75-'76 (less desirable) heads milled down some to increase combustion? Is there enough material there to allow for this?

    Sidenote; great site, excellent info! I am used to a couple other sites that are HIGHLY technical so I had big expectations. So far, my expectations have been met. Continue the great work gentleman.

  25. Default Re: What year Big Block Buick to Build?

    no, scrap heap those huge chamber heads, by the time you cut them down to get a good cc, your valves would rub through the pistons into the crank

    I may have a set of 70 heads I would be willing to part with They need rebuild.
    MarkO
    "There he goes. One of God's own prototypes. A high-powered mutant of some kind never even considered for mass production. Too weird to live, and too rare to die."-Raoul Duke
    Street Sleeper~'70 Skylark Holiday Coupe
    Build-> http://www.v8buick.com/showthread.ph...ge-Find/page10
    N2O-> http://www.v8buick.com/showthread.ph...-Nitrous-facts
    Hydraulic Clutch &T/O Bearing-> http://www.v8buick.com/showthread.ph...-chime-in-here

 

 
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