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The Orphan Small Block

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  • Joe L.
    Beyond Control Poster
    • February 1, 1988
    • 43193

    The Orphan Small Block

    As many folks know, Chevrolet and GM have produced, to date, 3 "generations" of small block engines. The first generation is the most widely produced. First used for 1955 model Chevrolets and Corvettes, it had a VERY long life. For the US market it was last used in a few truck models for the 2001 model year. It's still in production for SERVICE, too. It was produced in MANY different displacements over the years including 262, 265, 267, 302, 305, 307, 327, 350, and 400 cid displacements.

    Jumping ahead to the present day, the third generation engine was first used for the 1997 Corvette and was a completely new design engine, sharing virtually no parts with the earlier small block engines. Subsequently, it was used for the 1998 Camaro/Firebird and, thereafter, it was phased into trucks as the Gen I engines were phased out. The Gen III small block has been/is manufactured in both all cast iron, all aluminum, and aluminum/cast iron head/block material. It has been produced, to date, in 4.8, 5.3, 5.7, and 6.0 liter displacements.

    Sanwiched in between the Gen I and Gen III small blocks, though, is, of course, the Gen II small block. This is the engine that I call the "orphan small block". It lead a short but exciting life, never fulfilled its promise to replace the Gen I small block, but is, nevertheless, one of the more interesting events in the saga of the evolution of the small block engine. It was produced in only 2 displacments---4.3 Liter (for some Caprice) and 5.7 liter (for all other applications). Corvette and Camaro/Firebird engines were aluminum head/cast iron block wheras all other applications were all cast iron construction.

    It was never ORIGINALLY intended to be an "interim" engine; it was intended to replace the Gen I engine and soldier on for awhile for all small block vehicle applications. This never occurred, though. Shortly after its development began, GM saw the need to completely revamp the small block engine and development of the Gen III engine began about the time or, even, before the Gen II engine "hit the street". The Gen II engine was first used for 1992 Corvettes with LT1. For 1993 its use spread to Camaro/Firebirds applications and in 1994 it saw initial use in GM "B" body cars (Chevrolet Caprice/Impala, Buick Roadmaster, Oldsmobile Custom Cruiser, and Cadillac Brougham). The last use for the Gen II engine was for the 1997 Camaro/Firebird. So, the engine had a life span of only 6 model years. Not a single one was ever installed in PRODUCTION in a truck or any other GM vehicle. Without a doubt, the Gen II small block is and will increasingly become the rarest of the generations of small blocks since its PRODUCTION applications and installations were so limited.

    The Gen II engines offered several "revoltionary" design differences from the Gen I engines. Included in these were reverse flow cooling, a direct drive water pump, an optically-triggered distributor, and significant changes to the FI system design. As a result of these and other changes, the Gen II engine produced 55 HP more than the L-98, Gen I engine which it replaced in Corvettes and, later, Camaro/Firebirds. It was the rage when it debuted in 1992.

    Unfortunately, the very things that made the Gen II engine "revolutionary" in the fall of 1991 proved, in short order, to be its undoing. Not a single one of the revoltionary features of the Gen II engine were carried over into the design of the Gen III.

    In many ways, I feel that the Gen II engine was much maligned. They run very well and are, for the most part, quite trouble-free. I factory-ordered and purchased one of the first ones to hit the street in the fall of 1991. I still have it. I like the Lt1 and the ZF 6 speed transmission, the heaviest duty transmission ever installed in a Corvette to date.

    One other thing and the thing that made my 92 a "must have" for me when I saw the first one: I think that the Gen II small block, and especially the 1992 version of it, is one of, if not THE, best looking engines ever installed in a Corvette. The Gen II engine is "aesthetically perfect" in my mind---just an awesome looking engine in every respect. As far as looks go, its, in my opinion, in a league with only 2 other Corvette engines: the 1969 ZL1 and the 1990-95 LT5 (ZR1). To my eye, though, the LT1 has the edge for looks. This is, as I say, especially true for the 1992 version of the LT1. This was the only year that the LT1 received the magnesium valve covers similar to the L98 (although the 1992 LT1 left side valve cover was actually unique to the 1992 Corvette application and was never used on an L98).

    The Gen III engine offered fantastic new technology and huge increase in power (with much more to come). Its potential is what doomed the LT5. However, as great as the Gen III engine is, there is one quality that it just doesn't have---LOOKS. In my opinion, it's the ugliest engine ever installed in a Corvette. GM tried to "cover it up" with the plastic covers which, essentially, shield most of the engine from view. But, underneath the covers (or, au natural in Camaros/Firebirds and trucks) it's just plain "butt-ugly". I'm sorry to be so frank and uncomplimentary but that's just how I feel about it. But, as they say, looks aren't everything and, for an engine, it's really a minor matter, especially since I'm a big believer in function over form. It's just that, for a Corvette, the engine is SUPPOSED to look good (and, unfortunaely, the Gen III doesn't).
    In Appreciation of John Hinckley
  • Verle R.
    Extremely Frequent Poster
    • March 1, 1989
    • 1163

    #2
    Re: The Orphan Small Block

    Joe,

    I agree with completely on the Gen III engine, it is ugly!

    I am curious about something. Why didn't GM just redesign the top end of the small block, that is, install Gen III heads on the proven small block block and lower end?

    They continue to have bottom end problems with the Gen III engines losing main bearings.

    Verle

    Comment

    • Clem Z.
      Expired
      • January 1, 2006
      • 9427

      #3
      Re: The Orphan Small Block

      the gen III engine uses the same rod bearing inserts as the gen I and II and that is the only part that is a carryover. the 1 ignition coil per spark plug is what makes the gen III engine look funny and several companies now make a kit to move the coils over to the inter fender wells and supply a different rocker cover to clean up the top of the engine. a lot of GMs show cars with the gen III engines moved the coils for a cleaner look. edelbrock now sells a 4 barrel intake for the gen III engine and it comes with a special computer to run the ignition so people who do not want to fool with the fuel injection can put the gen III in other cars. i will bet that GM did the engineering on this project and let edelbrock do the manufacturing. the setup is in the latest GM performance catalog

      Comment

      • Joe L.
        Beyond Control Poster
        • February 1, 1988
        • 43193

        #4
        Re: The Orphan Small Block

        Verle-----

        I don't know the answer to your question. I expect, though, that GM figured that for competitive reasons, they needed a completely new engine. The foreign competition seems to come up with completely new engine designs on a regular basis, so GM might have figured that after 40 years they needed to come up with something totally new, too. For better of for worse. GM Powertrain's previous philosophy revolved around continuous refinement and improvement of older designs. But, the competition has forced them away from that.

        At the present time, the only "old" engine design in the entire GM stable is the 3800 V-6. This engine dates back to the old Buick V-8. Also, the current 3100 and 3400 engines are derived from the 60 degree V-6 engine developed for the old Chevrolet Citation family of cars which debuted in the later 70s. That engine has been completely revised to a form which is almost totally unrecognizable as being based on the original design and is being first used in the new Chevrolet Malibu. This engine will form the new "High Value" line of GM V-6 engines. Displacements will range from 3.5 to 3.9 liters. The 3.9 version will debut in the new Pontiac G6 later this year or early next year. The particular variant to be used in the top-end version of this car will have about 250 hp.

        All the other GM engines are new or relatively new and are not based upon old designs, at all. The new "High Feature" V-6 is a 60 degree DOHC design and is a completely "clean-sheet-of-paper" engine. It debuted at 3.6 liters and 255 hp in the 2004 Cadillac CTS and will also be used as an optional engine in the near future in the Buick Ranier and the Buick La Crosse. At some point, it will likely phase out the old 3800.

        The EcoTec 4 cylinder "global engine", which is relatively new, has become GM's only 4 cylinder engine for passenger cars. Variants of it will be used for ALL automotive 4 cylinder applications. A turbo-charged version at about 250 hp will be an optional engine in the new Pontiac Solstice. GM Powertrain has developmental turbocharged versions of this engine producing well over 800 hp. I understand that the Lingenfelter organization has produced over 1200 hp with turbocharged versions of the Ecotec.

        Trucks-only will get the relatively new 6 cylinder in-line DOHC engine as well as the brand new 4 and 5 cylinder derivatives thereof. Of course, the LS1-derived small blocks will also be widely used in trucks. A few will get the 8.1 L Gen VII big block.

        A revamped Northstar is in Cadillac's long-term future. A derivative is going to be used in the Pontiac Bonneville.
        In Appreciation of John Hinckley

        Comment

        • Joe L.
          Beyond Control Poster
          • February 1, 1988
          • 43193

          #5
          Re: The Orphan Small Block

          Clem-----

          Without a doubt, the coil-on-plug design of the Gen III engine is a major factor in "fouling the appearance" of this engine. However, even with re-located coils and improved valve covers (which GM might do for PRODUCTION versions in the future, too), it's hard for me to ever picture the Gen III as an attractive engine. The fundamental architecture of it just doesn't lend itself to that. It could be improved significantly but that's all that I could envision.
          In Appreciation of John Hinckley

          Comment

          • Mike Cobine

            #6
            Re: The Orphan Small Block

            One other thing and the thing that made my 92 a "must have" for me when I saw the first one: I think that the Gen II small block, and especially the 1992 version of it, is one of, if not THE, best looking engines ever installed in a Corvette. The Gen II engine is "aesthetically perfect" in my mind---just an awesome looking engine in every respect.

            Joe,

            You have good advice and good information, but this "aesthetically perfect" escapes me. I mean, compare the following URLs with a tri-power big block, or any of the old fuellies. Of course, I never considered any of the engines to really be "works of art" in looks. There are clean ones and there are cluttered monsters that look like a bundle of snakes with the hoses.



            The Corvette has so much plastic, who knows what it looks like as in this URL:
            1993

            Z06

            And as Clem said, it isn't that bad if you get the coils off:

            compared to an old one:


            Note the heads on these die cast models are the accessory mount style and the rear crankcase vent is covered.

            old 425 hp

            435 hp

            I guess it boils down to beauty is in the eye of the beholder. Almost anything I can see the engine is looks good to me. Most that you have two days of wading through hoses and plastic to get to the first spark plug is ugly to me.

            Comment

            • Duke W.
              Beyond Control Poster
              • January 1, 1993
              • 15610

              #7
              Re: The Orphan Small Block

              I completely agree with your analysis, Joe, but want to point out that virtually all manufacturers who attempt to "style" the engine compartment nowadays use plastic covers. Look under the hood of any Merc, BMW, or Audi.

              The "problem" with Gen III styling is, as you say, the coil on plug ignition, which a lot of other manufacturers use.

              I recently looked under the hood of an Audi S6, their hot new V-8 sport sedan that goes for something on the order of $75K, and there was so much plastic it didn't even look like there was an engine inside - relatively much "worse" than a modern Corvette.

              The "look" of a vintage Corvette engine is one reason we all like them. A glance under the hoods shows a "real" engine, with nicely detailed components, and all the Gen I FIs especially the '63-'65 are the best of the lot IMO.

              Duke

              Comment

              • Mike Cobine

                #8
                Re: The Orphan Small Block

                I am curious about something. Why didn't GM just redesign the top end of the small block, that is, install Gen III heads on the proven small block block and lower end?


                I have no inside information, but my first guess is that since they have gone to a longer stroke to reduce emissions and improve low end torque, they wanted more room for the crank.

                While the 400 crank swap into the 350 block is common, you have to be careful in your rod and cam selection as they are close. While the original design was great for being compact and lightweight relative to the engines of the time, they made their original design work on a displacement of roughly 240 cid. It was only when they realized they could have 265 for the price of 240, and blow Ford's 239 cid V8 away, that the 265 was born. No one was thinking of 400 inch engines. Unfortunately, Ford didn't sit still and put out a 272 cid to Chevy's 265 in '55. Darn good thing Chevy didn't stick to the 240 cid.

                In '56, Ford had the 292 and 312 V8s added and Chevy went to 283 in '57, with FI as a trump card. The rest is history.

                But still, the original small block Chevy V8 was designed for 240 cid. To get 400 cid out of it is quite the achievement.

                Chevrolet may be plans for other larger displacements, and probably based on stroke changes rather than bore changes. So a new block design allows moving the cam to allow for future growth, and allows spreading the bore centers for future growth.

                The logic is that if you bored for more size, you have to use a different block and different pistons. If you stroke for different size, you use a different crank and different pistons. I imagine a crank is much cheaper than a block to manufacture.

                With the current 4.8 L, 5.3 L, and 6.0 L engines, much of the previous large V6 and small block V8 applications are covered. It could be conceivable that the big block will be phased out and the Gen III be changed to larger than 6.0 L. Friends with the Gen III in 3/4 ton trucks say they get great power so I'd think the intro of a Gen III around 7 L is something that is quite possible. How many times do you hear of talk of the Z06 with a 427? I'm sure they don't mean a Mark V or such.

                And think of the savings to Chevrolet if they can do 4.8, 5.3, 6.0, and 7.0 with one block instead of two different engines.

                Then I also think that from the Chevrolet engineers I've met of the new generation, they are itching to prove themselves with a legend. They want their names to be like Cole, Duntov, and Mitchell. You can't do that using Cole's SBC, Duntov's chassis, and Mitchell's style. You can only build a legend if you build it from scratch.

                Just MHO, nothing more.

                Comment

                • Clem Z.
                  Expired
                  • January 1, 2006
                  • 9427

                  #9
                  Re: The Orphan Small Block

                  joe i built a all aluminum BBC for a drag boat back in the 70s and the owner had ground and polished the whole engine to a shine before he bought it to me. i have not seen this guy for years but my guess he died from silicosis from all the aluminum dust.

                  Comment

                  • Chas Kingston

                    #10

                    Comment

                    • Wayne W.
                      Extremely Frequent Poster
                      • April 30, 1982
                      • 3605

                      #11
                      Re: The Orphan Small Block

                      Me neither Geezer. Old timers learned not to put the distributor there a long time ago. These young whipper snappers have to learn the hard way.

                      Comment

                      • Terry M.
                        Beyond Control Poster
                        • September 30, 1980
                        • 15573

                        #12
                        Re: The Orphan Small Block

                        Gee Geezer, I feel good about my skills. I beat the book on Monday, and that means I should do better yet on the next water/pump distributor change that is coming up for the other Caprice. In spite of the water pump leak, the distributor was still holding up, and I didn't feel bad about changing the distributor at 140K. The Gen II is a high maintenance engine, unlike the Gen I, but I love both of mine. While there is no inexpensive alternative for the distributor, NAPA sells a rebuilt water pump for $40, if cost matters.
                        The good guy price on the GM water pump is 120-140 and 200 on the distributor.
                        BTW: If you decide to dump the Roadmonster wagon, give me a shout - unless it is a woodie. Next to a 1A2 wagon the RM or Olds 94-96 wagon is right there on my list.
                        Joe has my vote for his sentiments about the Gen II - the best of both the old and the new.
                        Terry

                        Comment

                        • Joe L.
                          Beyond Control Poster
                          • February 1, 1988
                          • 43193

                          #13
                          Re: The Orphan Small Block

                          Geezer-----

                          The water pump and Opti-Spark distributor are 2 of the real weak points of the Gen II. My first design, first edition distributor failed at 3,000 miles. It was a huge job for the dealer to replace the distributor, especially at the time since service technicians had never done anything like this before. They also found that the waterpump was leaking so they replaced that, too.

                          The first design, first edition distributor (used for about the first 7,000 1992 Corvettes), had no ventilation, at all. So, it was immune to external water intrusion. However, it wasn't immune to optical sensor fogging caused by the lack of ventilation. The first design, second edition had 3 small holes on the bottom of the aluminum housing for ventilation. Water intrusion from leaking waterpumps can harm these.

                          The second design distributors used from 1994 through 1997 use a closed, vacuum ventilation system. I'm surprised that water intrusion from a failed waterpump is damaging to them.

                          Before I retired, I spoke with our City's fleet manager and shop supervisor about their experience with the Gen II engines in police cars. They rack up hundreds of thousands of miles on these cars (especially, since the police department did not want to let go of the Caprices as they performed FAR, FAR better than the Ford Crown Victoria). They told me that they had very little problem with distributor failure on these cars whether it was the first or second design distributors.

                          In any event, the direct drive waterpump, which was supposed to eliminate the problem of bearing failure due to the effect of drive belt side loading didn't work out like it was supposed to. It did eliminate the belt side loading problem. However, the pumps fail for other reasons and have a shorter life than belt driven pumps. So, it was one step forward and two backward.

                          As far as Gen II performance goes, ask any policeman that has driven both the Caprice with the Gen II engine or the Crown Victoria with the SOHC "modular" engine which he prefers.
                          In Appreciation of John Hinckley

                          Comment

                          • Chas Kingston

                            #14

                            Comment

                            • Joe L.
                              Beyond Control Poster
                              • February 1, 1988
                              • 43193

                              #15
                              Re: The Orphan Small Block

                              Geezer-----

                              I think that's "overkill" on the dealer's part. I could see replacing the waterpump whenever the distributor has to be replaced since you have to remove the waterpump, anyway, to get at the distributor. Since the cost of the labor (if a dealer is doing the job) is more than the cost of waterpump, itself, I think that it would just about always make good economic sence to replace it whenever they're in there for the distributor.

                              However, when replacing the waterpump, a great deal of additional work is necessary to replace the distributor. Plus, the distributor, itself, is about twice the cost of the waterpump. Usually, if the distributor is going to fail because of water intrusion (as a result of a failed waterpump seal or otherwise), it will happen very quickly. So, by the time that you know that the waterpump needs replacing, you'll know that the distributor does, too. If the distributor is still functioning ok when the waterpump is replaced, the chances are very great that it will continue to function properly and there's no reason to believe that the failure of the waterpump adversely affected the distributor.

                              Something that I've often wondered about is whether the distributors actually need to be replaced when they fail. These distributors are, basically, a pretty simple device. They have a shutter wheel, an optical sensor unit, a rotor, and a cap. The only thing that really goes wrong with them is that the optical sensor lens gets "clouded" or otherwise impaired due to moisture-related intrusion/contamination. So, why couldn't one just open them up, clean the optical unit (which, itself, is sealed, potted, and thus protected from any moisture intrusion) and restore the unit to perfect functionality? The cap and rotor are also available as seperate parts if they need to be replaced. They aren't available through the GM parts system, but they are available through the Delco parts system or aftermarket sources (like NAPA, Sorenson, Echlin, etc.).
                              In Appreciation of John Hinckley

                              Comment

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