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The Orphan Small Block

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

    #16
    go to

    www.charm.net/~mchaney/optisprk/optisprk.htm for more info on taking apart the opticspark

    Comment

    • Terry M.
      Beyond Control Poster
      • September 30, 1980
      • 15595

      #17
      Re: The Orphan Small Block

      If you look at the link Clem posted you can see the corrosion damage on the internal parts of the distributor. You can even see the water line on some of them. And the pictured unit is the latest (1995 +) design with the best available ventilation.
      I believe anytime the water pump is off consideration should be given to changing the distributor. The decision should be based on the age of the distributor, the duration of the water pump leak, and engine performance.
      I haven't priced the cap and rotor kit lately, but I believe through Delco their cost is a substantial percentage of the cost of the distributor. Further those of us living in intemperate climes find removing the four inverted Torx T5 screws for the cap next to impossible unless anti-seize has been applied to them. Even with the Snap-on deep socket, I was able to get only two of them lose from the distributor I replaced this week, and my cars spent the first five years of their lives in North Carolina.
      In an earlier post I described the modification to the water pump weep hole that allows the use of a tube to direct water pump seepage away from the distributor, but once we get to the point of judging the new LT1 that modification will become anethma to those who intend to have their Corvettes judged by us. Additionally that mod will provide no defense against water pump leaks from the shaft bearing - my situation.
      When servicing the distributor with ventilation provisions, consideration should also be given to replacing the vacuum harness which is available as an assembly with new hoses, filter, clamps and protective tube.
      BTW: Excellent link Clem.
      Terry

      Comment

      • Joe L.
        Beyond Control Poster
        • February 1, 1988
        • 43207

        #18
        Re: The Orphan Small Block

        Terry-----

        Yes, I hadn't checked before but I've checked now and the cap/rotor kit for the Opti-Spark distributors is outrageous, especially considering all you get is the cap and rotor. They are as follows:

        1992-94 (shaft drive)----GM #10457735 (Delco D327A)= GM list $377.96

        1995-96 (paddle drive)---GM #10457293 (Delco D8301)= GM list 216.92

        Of course, the above would be a lot less expensive through Delco or competitive GM dealers, but still a lot of money. Heck, you could just about get a Delco D-308 or 309 with "Delco-Remy script" and "patent pending" for less than these. I purchased an Echlin or NAPA kit on eBay several years ago for just a few dollars; I guess a got a bargain.

        There was an article in Corvette Fever or Vette Magazine a few years ago which gave detailed instructions for modifying and adding the vacuum ventillation system to the 92-94 Opti-Sparks. I abandoned the idea, though, after I learned from our shop division that they experienced no higher failure rate with the "naturally vented" Opti-Spark units as compared to the vacuum ventillated versions.
        In Appreciation of John Hinckley

        Comment

        • Terry M.
          Beyond Control Poster
          • September 30, 1980
          • 15595

          #19
          The Orphan Small Block distributor

          In the earlier post on this subject I believe someone posted the link to that story Joe. At the time it was available at the magazine's web site. It looked like an excellent modification to the earlier units, if one has no intentions of entering judging.
          While all these optical distributors and/or their parts are expensive now, we all know what will happen when they are no longer available from Delco. We will all refer to these times as the good old days.
          Terry

          Comment

          • Patrick H.
            Beyond Control Poster
            • December 1, 1989
            • 11640

            #20
            Re: The Orphan Small Block distributor

            Time to buy one for the 92 while we still can....

            Patrick
            Vice-Chairman (West), Michigan Chapter NCRS
            71 "deer modified" coupe
            72 5-Star Bowtie / Duntov coupe. https://www.flickr.com/photos/124695...57649252735124
            2008 coupe
            Available stickers: Engine suffix code, exhaust tips & mufflers, shocks, AIR diverter valve broadcast code.

            Comment

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

              #21
              why cant you convert to a rear distributor? *NM*

              Comment

              • Joe L.
                Beyond Control Poster
                • February 1, 1988
                • 43207

                #22
                Re: The Orphan Small Block distributor

                Patrick-----

                I've got 3 new Delco units in stock [none for sale now or ever].
                In Appreciation of John Hinckley

                Comment

                • Joe L.
                  Beyond Control Poster
                  • February 1, 1988
                  • 43207

                  #23
                  Re: why cant you convert to a rear distributor?

                  Clem-----

                  It could be done, but it would require a multitude of other changes. The LT1 camshaft, as is, will accept a conventional distributor (it has the gear for the purpose of oil pump drive). However, the LT1 plenum manifold is not designed to accept a conventional distributor. I doubt that it could be so-modified, so the whole intake system would need to be swapped out for something else which is compatible with a conventional distributor. Due to the LT1's reverse cooling, an L98 set-up would not work. Beyond that, the LT1 ECM is designed to work with the Opti-Spark type unit. Whatever would need to be done to change that I wouldn't even want to think of getting involved in. In any event, the mods would make the engine smog-illegal and, at least in California, you'd never get it to pass the biannual inspection.
                  In Appreciation of John Hinckley

                  Comment

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

                    #24
                    Re: why cant you convert to a rear distributor?

                    i know that GM sells 4 barrel intake to be used with LT-4 and has a hole for the distributor. i have seen a special machined spacer at trade show to install the distributor in the FI intake once you machine the hole in the FI base plate. you also need a "small body" distributor converted to HEI

                    Comment

                    • Joe L.
                      Beyond Control Poster
                      • February 1, 1988
                      • 43207

                      #25
                      Re: The Orphan Small Block distributor

                      Terry------

                      Another thing that I've often thought about is this: apparently, the primary point of water/moisture intrusion into the unit is the joint between the cap and the aluminum backing plate/drive mechanism. Why there isn't some sort of positive and effective seal in this area is a mystery to me. Anyway, it would seem to me that the interface area could be treated with Permatex "Kleen and Prime" and then a bead of silicone sealer laid down at the interface. Then, the bead could be tooled with a finger so that the area was completely covered/sealed AND a professional looking application would exist. If clear silicone sealer (like that used for aquaria) was used, it would be almost visibly undetectable, especially considering the location of the sealer on the unit.

                      For second design units, it would seem to me that the sealing I described above would make the unit completely impervious to moisture or water damage from a leaking waterpump, rain splash, or anything else (except atmospheric moisture present in the ventilation, of course). From what's been reported about these units, though, it seems that the waterpump leakage is a primary cause of distributor failure.

                      First design distributors would, of course, still have the 3 ventilation holes on the bottom of the aluminum housing. However, these should't represent much of an intrusion point for leakage from the waterpump. So, if the first design distributors were sealed as I described above, I would think that the waterpump as a source of distributor problems would be eliminated, too.
                      In Appreciation of John Hinckley

                      Comment

                      • Joe L.
                        Beyond Control Poster
                        • February 1, 1988
                        • 43207

                        #26
                        Re: The Orphan Small Block

                        Mike-----

                        First of all, a few specific comments:

                        1) For the most part, the LT1 engines that you have pictured via links are, basically, salvage-type engines shown in an as-removed from vehicle condition. ANY engine seen under such circumstances would look very unimpressive. So, in my opinion, the pictures that you linked are relatively meaningless in the context that you offerred them. If the LT1 engines pictured are unimpressive, then a similarly pictured LS1 or LS6 would be even MORE unimpressive relative to appearance. I've seen more than a few LS1s and LS6s under such conditions and I can assure you that they are VERY unimpressive;

                        2) The one in-car LT1 engine that you show via link looks very good to me. You can see most of the top of the engine from valve cover-to-valve cover and from stem-to-stern. Up close, one could see portions of the sides of the engine and manifolds and much of the front of the engine. This is not all that much different than 60s and 70s Corvette engines. It's too bad, though, that Chevrolet dropped the magnesium valve covers after 1992; they would have made this engine look SO MUCH BETTER;

                        3) The 50s and 60s Corvette engines that you show via link or reference look OUTSTANDING to me, too. If you will note in my original post, I NEVER said that those engines looked bad. Quite the contrary, it is those very engines, and others, that make engine appearance a CORVETTE TRADITION and, in my mind, an expectation. Certainly, I would say that some of the engines used in Corvettes looked better than others (like a 1969 ZL-1 looks better than a 1966 L-72-----NOT a lot better, but, IN MY OPINION, better; or, a 1995 LT5 looks better than a 1971 LS-6-----NOT a lot better, but, IN MY OPINION, better).

                        4) When I used the term "aesthetically perfect" you will note that both now and in my original post, the term is enclosed between parentheses. Among other things, this means that the term is not to be taken literally AND that it IS NOT A PRECISE TERM. But, I'll describe later why, IN MY OPINION, the LT1 engine is "aesthetically perfect".

                        Now, to get to the "meat of the matter". It's definitely true that beauty is in the eyes of the beholder. That's the reason that my comments regarding the various engines were offerred and, hopefully, interpretted, as OPINIONS and NOT statements of fact. Notwithstanding this, I think that it can be generally stated that certain things can be regarded as generally attractive and certain things as generally unattractive. For example, most folks would say that a rose or Yosemite Valley are "beautiful" and they would also say that something like the Hunchback of Notre Dame is NOT beautiful in a material or physical sense.

                        So, what are the attributes that make an engine, or anything else for that matter, appear attractive and what make things unattractive? Well, in my mind one of the important attributes for beauty is SYMMETRY and another is PROPORTIONALITY. Color and contrast of colors are two other important elements. Chrome or stainless steel elements, understated rather than over-stated, are an important element which contributes to attractiveness as are aluminum elements. There are many other ethereal elements which come into play, too, in the OVERALL impression and degree of attractiveness or lack thereof.

                        For an engine, valve covers are a MAJOR factor in generating the overall impression of attractiveness. Most aftermarket valve covers are pathetic in this regard. They are too overstated, too cheesy, or too something else. I've never seen one that I liked. On the other hand, I regard the 65-74 PRODUCTION big block valve covers to be one of the most attractive valve covers ever made. Elegant in their simplicity and "subtley voluptuous" in contour. In my opinion, in a thousand years, no one could come up with a valve cover which better "fit" the big block engine's other physical characteristics. It was a MASTERPIECE of design and complemented the basic architecture of the engine PEFECTLY.

                        Wide cylinder heads are an attribute which contributes to the attactiveness of an engine. The mystique of the original Chrysler Hemi was not based on the term "Hemi", but rather the agrressive appearance of the wide cylinder heads with center mounted spark plugs. The center mounted spark plugs and shape of the cylinder heads and valve covers provided great SYMMETRY. Engines with 2X4 also had a long and SYMMETRICAL air cleaner, adding another attractive element.

                        The cylinder heads on a big block Chevrolet are relatively wide AND APPEAR WIDER. That's one of the things that contributes to the attactiveness of the engine.

                        One of the great attractive features of BOTH big block and Gen I and II small block Chevrolet engines is the APPARENT PROPORTIONALITY of the engines. The engines are PROPORTIONAL in width and height. They are neither too tall for their width nor too wide for their height. Picture the person that weighs 120 pounds and is 6' 2" tall or the person that is 5' 2" tall and weighs 280 pounds. Do you think that either of these folks would be generally regarded as attractive? The reason is that their girth is not PROPORTIONAL to their height. PROPORTIONALITY is an element in attractiveness of an engine just like it is for so many other things.

                        The Gen III small block has WHAT APPEAR TO BE narrow, "flat" valve covers with no style or character, at all. Worse yet, they're bespoiled by attached ignition coils. Even if the coils could be re-located and the appearance of the valve covers improved, they would still suffer from the inherent architecture of the engine and could not be made vastly better in appearance as a result. Certainly, GM is not going to redesign the engine with appearance as a primary goal. That would be absurd. The engine was designed with FUNCTIONALITY as the primary objective and appearance "way down the totem pole", if it was on the totem pole, at all. That's as it should be, too. ALWAYS, function OVER form.

                        The Gen III engine's cylinder heads are not really so narrow, but they APPEAR narrow. It doesn't make the engine unattractive, it just doesn't contribute to making the engine attractive.

                        With respect to proportionality, the Gen III engine also APPEARS disproportional with respect to height versus width. I don't know if this is actually the case, but the engine APPEARS narrow and tall. This doesn't make the engine unattractive, it just doesn't contribute to making it attractive.

                        For a Corvette, as a matter of tradition, the appearance of the engine IS important. There is probably no other car ever built that folks always want to "see the engine". With a Porsche, no one seems to care or ask what the engine looks like (not that they could EVER really see it, anyway). With an Acura NSX, nobody really cares what the engine looks like. Even with an old AC Cobra, no one really cared what the engine looked like. But, with a Corvette, folks want to see under the hood and EXPECT to see an impressive engine. It's a tradition that's been established as a result of those dynamite-looking engines of the 50s and 60s. It's something that has never died.

                        It's very true that most modern engines are hidden under lots of pipes, tubes, and shields. However, the LT1 engines, while partially obscured, were mostly visible, just like in the old days. In my opinion, the elements of PROPORTIONALITY were "perfect" on this engine and the SYMMETRY was "perfect" or "near-perfect". The engine appeared "tight" and compact. The waterpump, distributor, and spark plug wire configuration contributed to an aggressive and "race-ready" appearance (as problematic as they might otherwise be) and futher contributed to the symmetry of the engine.

                        While, IN MY OPINION, the 1969 ZL-1, 1990-95 LT5, and the 1992 LT1 were the best looking engines ever installed in a Corvette, I don't think that they were the best looking engines ever installed in an American car. IN MY OPINION, that honor goes to the Ford Boss 429 and the 2002 Ford Mustang Cobra DOHC. I seriously considered buying a Mustang Cobra because I thought the engine was the best looking thing I ever saw (you all KNOW that I'm a "sucker for a pretty face", though). Of course, neither the Boss 429 nor the DOHC Mustang Cobra were really all that great as far as performance goes, but, open the hood and I'd "melt" right on the spot. Sorry to agrandize a Ford on this board, but I have to give credit where credit is due (I do agree, though, that neither engine was up to Chevrolet perfomance standards).

                        Anyway, I'm including another picture of the 1992 LT1. This is the very picture that made me "fall in love" with the looks of the engine and "have to have" a 1992 Corvette. The engine in my car still looks very much like this one and you can see almost as much of it as it sits in the car as you can in this photo. I still think that it's the best looking engine ever installed in a Corvette. But, you don't have to if you don't want to.




                        Attached Files
                        In Appreciation of John Hinckley

                        Comment

                        • Terry M.
                          Beyond Control Poster
                          • September 30, 1980
                          • 15595

                          #27
                          Re: The Orphan Small Block distributor

                          Joe,
                          I agree one could improve the seal of the distributor cap to housing in a number of ways, and anything would be an improvement. Vigilance for any signs of water pump leakage is important as well. None of these actions will negate the fact that the distributor components will eventually wear and require replacement of part or all of the unit.
                          In spite of the proximity to the water pump I believe the distributor drive from the front of the cam is a mechanical improvement, as is the gear drive for the water pump. The light trigger is also relatively trouble free, and another technical innovation. The packaging of these items required some compromises which have resulted in the shortcomings we have beaten to death.
                          Have you ever seen the SAE paper on the Gen II LT1?
                          Terry

                          Comment

                          • Joe L.
                            Beyond Control Poster
                            • February 1, 1988
                            • 43207

                            #28
                            Re: The Orphan Small Block distributor

                            Terry-----

                            No, I have not seen the SAE paper on the LT1. I was not even aware of it.
                            In Appreciation of John Hinckley

                            Comment

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