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  • If you havent seen a fuel car run, GO SEE THEM. Its an experience of a lifetime for a gearhead. I worked around jets for most of my adult life and a hemi on nitro is far louder and way more impressive... Well its on par with an F15 doing a full burner engine run but is completely different.

    Olds has a small and big block, easily identified by the head casting code. For small blocks its a number (3-5-7), for big Olds its a letter (A,C,E,J) are the most numerous codes. The heads will physically bolt to big or small blocks, and its really a matter of deck height and main journal size.

    Pontiac engines have no big or small block and while the displacement started at 265ci way back in 55, it grew to 455ci in 1970, and with aftermarket cranks you can get 498ci from 400 or 455 blocks. Damn near everything on them interchanges, as long as you know the year breaks when they changed things like valve inclination angle, and intake flange angles, then you have small journal 3" and big journal engines 3.25". That isnt a big nor small block thing, its the main journal size and 421,428, and 455 engines have the large journal, the rest have 3" all the way back to the late 50s. You can physically bolt any Pontiac head to any Pontiac block and with the right intake manifold it will all fit together. They all use the same size rod at 6.625", the same pushrods (except for Ram Air-IV which had thicker but not longer pushrods) and all of them had the ball stud rocker arms, because it was designed by a Pontiac engineer in his basement, which chevy and the rest copied. Its easier to say what doesnt interchange, which is pistons, cranks, and rings. The Pontiac used cylinder head changes to raise or lower the compression ratio rather than a dished piston. You can get as low as 7.7:1 on a 455 with one head and 12:1 on the same engine with another head, and both heads will have a 2.11 intake valve.

    All of this is for the 50s, 60s and mid 70s engines, because in 77 they made the 301 and a smaller version that is hardly seen. Not much interchanges with the 301, but it looks quite a lot like the older engines. They are easily spotted by a dipstick poking out from behind the drivers side head. All the others had the dipstick tube on the passenger side between #2 and #4 cylinders. The nice thing about a 301 is that a 400 or 455 will bolt in where it is sitting real easy.

    There is no big block Pontiac 400, chevy is the only one that made a small block 400. Anyone that tells you theyhave a big block 400 Pontiac doesnt know what they are talking about, or they are pulling your leg, usually the former. The really fun thing about a Pontiac is it can displace more than 500" and be dressed up to look like a 326 or even a 265. I used to tell people all the time that my 455 was a 350 or a 310, they had no way of knowing unless they know the very minor differences.

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    • Marky - I TOLD your our Pontiac guys would fill in the blanks!

      And Ford had the MEL series (Mercury, Edsel, Lincoln) but they have limited performance potential and almost no aftermarket support. It's probably a "Big Block" but that part of the family tree died out.

      Buick had a REAL Big Block (430, 455 mostly) and they were BAD a$$. Great heads but needed oiling system mods if used in performance applications. The small block Buicks covered several designs including the all aluminum 215 V-8 (love them little suckers) which were based on the V6. Also had a 300 ('64 only IIRC) which was a cast iron block version of the 215 but still with aluminum heads. Then the 340 which I think was a 300 with iron heads and a little more displacement but I'm not positive on that one, followed by the Buick 350 which was a new design and has nothing in common with other GM 350s. The 350 is most often referred to as the Small Block Buick and has some performance potential. Power Block did a build on one a while back and it made great power.

      Any questions? Happy to answer them. I think it's excellent that you're asking these questions as lots of guys throw statements around and really have NO idea of what they're talking about. Better to have REAL info!

      Dan

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      • I get tickled with Fords... a lot of guys call a 351 Cleveland a "Big block" , but it's 9.2" deck height is smaller than a 9.5" deck height 351 Windsor. Still, if you ask "them" ... "They" will say that a 351w is a small block. Interesting that it is called a Small block when it would really be a Medium block. The Small block is a 302 at 8.2" deck in my mind.

        You'll here "Tall Deck" thrown around too, the above example of a 351w and 302 is an example of deck differences on the same basic block platform.



        Deck height in this post meaning the distance between the centerline of the crank and the blocks cylinder deck
        Last edited by Beagle; February 1, 2013, 09:41 AM.
        Flying south, with a flock of bird dogs.

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        • coincidentally, nelson posted a big block vid.
          this has some classic problems conquered for car use.



          this is the real thing in that, the goal was to max power at slow rpms.

          this one is at 400+ foot pounds at 2100.
          a classic big block, as in way back at the beginning kinda classic.

          my first impression of big block earning it was a 65 chevelle. all factory.

          after all the engines he posted..this is the one that cracked the dyno, and it was the classic way.

          another way to look at big block and small block. As gas is very fast, formula 1 uses the same fuel in modern times to do this:


          it is up to the builder, small block mind or big.
          formula 1 or diesel.

          I mention diesel, as that is why big blocks hang around for outrageous drag racing today..they are outdone in the working world by something as simple as a 12v cummins.

          the old big block used to be a diesel type discipline.

          I like the one in nelsons video. that is old school, even the spacer for tall deck and dual plane.

          I currently play with formula 1 type think with a japanese engine, 2.65 inch stroke. it is so fast, not even the factory tuned them..they guessd at it (it shipped in the 80s..).

          ..which leads to false impressions of old engines. (big or small). Gm used to just slob the big blocks, same excuse as the little formula 1s...no tune truly available until the early 90s.
          Last edited by Barry Donovan; February 1, 2013, 01:29 PM.
          Previously boxer3main
          the death rate and fairy tales cannot kill the nature left behind.

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          • Anyone that thinks a 351 Cleveland is a "big block" needs a slap in the back of the head and needs to be sent to the back of the line.

            Present company excepted, of course.
            I'm still learning

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            • Thanks for the drawing Beags. I threw out the term "raised deck" like Marky would know WTH I was talking about. None of us are born knowing this stuff.

              Dan

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              • Great stuff

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                • Lots of guys say the Cleveland is a big block, but really the closest that design gets to a big block is the M, which has a raised deck, larger mains/crank, and the same bellhousing pattern as the 429/460. Other than that, its a Cleveland with more mass. Got in an argument with one guy on a Mustang forum who thought the 429/460 was the only big block and the FE (352,360,390,406,410,427,428) were not big blocks. He just couldnt wrap his head around the idea that Ford had different engine families with overlapping displacements, but very different architecture.

                  Since we are on Clevelands, here is the difference between the 2V, and 4V. The V means venturi in 60s Ford speak, so its 2 barrel or 4 barrel heads. The 2V came with a 2 barrel carb, and the 4V was obviously 4 barrel. The 4V is on the left, and the 2V is on the right, and these heads will bolt easily to the same engine. Some 4V engines had the same cam as the 2V, and Ford was stingy with lift and duration in the 60s and 70s, so all it takes is a cam to really wake either of these heads from the sleepy doldrums of stock cams.



                  This pic shows the canted valve arrangement of the Cleveland. It shares this layout with the big chevy. Using a head like this requires different reliefs in the piston crown so the valves dont hit. The second pic shows how the combustion chamber looks in a canted valve head. Its quite different from what is called a wedge head, and those were on almost all the other over head valve engines that werent Hemi or canted.





                  This is a Pontiac head with the valves lined up. GM did things somewhat different from Ford, in that the valves are arranged EI-IE-EI-IE. I = intake E = exhaust. The smaller valves are the exhaust. Ford decided that IE-IE-IE-IE worked better for them, and big Chevy had to go with that layout due to packaging issues with the big ports. The wedge heads have the valves lined up which is a remnant of the shaft rocker arm systems used before the ball stud came about.





                  This is what a Cleveland looks like (painted Pontiac blue) and its definitely a small block even if it is wider than a 302. The 351C 4V impressed me enough in my youth that I am a big fan of them, to the point that they are pretty much the only engine under 400ci I will build. The first engine that scared me was a 4V in my 72 Mustang. All it had was a mild cam and headers, and that car wold have given my GTO and its 455 a hard run.

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                  • Todd, I HAVE to meet you some day! Great info for a newbie.

                    Markymark - Hope your head hasn't exploded! We've given you a LOT of info in a couple of pages.

                    Another tidbit so you can sound like a smart guy - The FE is the only engine (as far as I can recall) that has the valve cover sit partly on the head and partly on the intake manifold. As you walk around a car show you can pick out an FE pretty definitively. Not sure this is true for a Boss 429 Hemi/DOHC/SOHC but those are pretty easy to pick out of a crowd.

                    BTW - are you clear about the word "displacement" (or cubic inches - cubic centimeters in metric)? I won't go into the definition if you already have that.

                    Dan
                    Last edited by DanStokes; February 2, 2013, 04:42 PM.

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                    • Sometime Dan, maybe in Ohio when I have a car to run at Wilmington. I just wish I had a hemi laying around so I could show him the differences. Got a buddy in town with the early ones, but the weather is utter crap lately.

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                      • that's a hemispherical combustion chamber... even if it is a Honda. haha.
                        Flying south, with a flock of bird dogs.

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                        • Marky - I don't know if you can tell from Beag's pic but that combustion chamber looks like half a grapefruit with 2 (in this case) valves in it. The piston is shaped to fit into that half sphere and the shape is arguably the best for valve placement, cylinder filling and other improved power-making properties. The Buick Nailhead actually has a similar shape but not nearly as ideal as the Chrysler - or Honda, in this case. I'll try to remember to take a pic of my Nailhead when I'm out in the shop.

                          Dan
                          Last edited by DanStokes; February 3, 2013, 07:16 PM.

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                          • Normally I dont like to hotlink to other pages, uses up their bandwidth, but I didnt want to grab the pic and put it on my photobucket either. Here is a hemi head, the valves are not aligned front to back, they are set up side to side for a straight shot into and out of the chamber.

                            A drawback to the hemi design is you need a big dome to raise compression and that makes for a heavy piston. A heavy piston will tends to stretch or snap the rod as the crank swings through top dead center (TDC) and pulls the pistons back down on the intake stroke. Thus it limits RPM and added mass in the reciprocating assembly makes the engine rev slower while putting more loads on all the parts connected to it.

                            Thanks to hothemideads.com for the pic

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                            • the honda pic is mine ... 125cc of screaming glory, and I think it redlines around 10,000. That's when it quit pulling anyway. HA! The cam journal is usually the first thing to go iirc). haha.

                              Todd brings up another topic - "solid dome" or "hollow dome" piston or Dish (reverse dome) or Flat top pistion...



                              Figuring "compression ratio" is as easy as knowing the area of the cylinder with the piston at BDC and the same are with the piston at TDC, it's a ratio of bigger area compressed into smaller area.

                              The chamber area in the head and the piston crown shape can have a dramatic effect on this.
                              Last edited by Beagle; February 4, 2013, 06:48 AM.
                              Flying south, with a flock of bird dogs.

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