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Thread: 1957-283 front main seal in neoprean?

  1. #1
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    1957-283 front main seal in neoprean?

    Dose any gear head out their know if they are making a neoprene replacement style rear main seal for a 57- 283? The gernal or holder for the seal on a 57 Chev. 283 has the rope shape, and in 1958 the gernal became a" vee" shape with a flat bottom, to except the new and improved neoprene rear main seal. Also is their a benefit to hot tanking the motor prior to a rebuild, compared to cooking it out? Did they make a better breathing ram horn manifold for the corvette283 compared to the 57 passenger car? I have seen vette ones listed at around 2", I believe . do the vette ones have a different angle to the engine pipe? I am soon going to have my 283 motor rebuilt , and I have a set of 1957" power pac 539 heads" I am going to use on my Nomad which was originally a two barrel car.I will have the s/s exhaust inserts installed on the exhaust side, and I am pretty sure that the power pac option use a slightly different cam. Can anyone recommend the best quaility cam, and rebuild parts needed like rings ect?
    Last edited by nomad; 02-24-2019 at 06:22 AM. Reason: corretion

  2. #2
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    Dose any gear head out their know if they are making a neoprene replacement style front main seal for a 57- 283? The gernal or holder for the seal on a 57 Chev. 283 has the rope shape, and in 1958 the gernal became a" vee" shape with a flat bottom, to except the new and improved neoprene front main seal.
    Standard neoprene front seals fit the timing cover and crankshaft on a 57 283. That's what you get when you buy a replacement.

    Also is their a benefit to hot tanking the motor prior to a rebuild, compared to cooking it out?
    It's unclear what you mean by "cooking it out". If you take the block to a real automotive machine shop they will clean the block with an acceptable process prior to machine work. The old school "hot tanking" has been modified due to EPA requirements.

    Did they make a better breathing ram horn manifold for the corvette283 compared to the 57 passenger car? I have seen vette ones listed at around 2", I believe . do the vette ones have a different angle to the engine pipe?
    Most ram horn manifolds have a 2" outlet. There were ram horn manifolds made in the 60s for high performance 327s that had 2-1/2" outlets (cars and Corvettes). They are reproduced. Ram horn manifolds over the years had various outlet orientations. The 57 ones and the 2-1/2" ones have a vertical, centered outlet. It's no problem for a muffler shop to make up a mating head pipe.

    Many choices on camshafts and other rebuild parts. Best thing is to consult your machinist/engine builder and use what he recommends.

  3. #3
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    I think you are referring to rear main rope seal, and yes they do have a neoprene replacement.
    https://www.ebay.com/itm/1955-1956-1...item237e2c7520

    I would also suggest the one piece oil pan gasket
    https://www.classicchevy.com/chevy-e...1955-1957.html

    In 57 I'm pretty sure the corvette used the same exhaust manifolds

  4. #4
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    Hello Rick, and thanks for your reply. One friend told me that their machine shop just heats up the bare block, and cooks out the old debris. And another friend sent his motor to a certain machine shop because he said that they have a hot tank and hot tank out the debris. When you say that the old school hot tanking method has been modified due to the EPA, in what way has the hot tanking method been modified? Do you believe that just cooking it out is just as good? Also thanks for your info on the 60's ram horn 2-1/2" exhaust manifolds. I would think that if both types have a vertical, centered out outlet, that it should except a stock ordered 1957 dual exhaust pipe kit, as long as the 2-1/2" one has the same length port and the studs are spaced the same. I once had a 57 283 motor rebuilt and the rear main leaked badly right from the beginning .My mechanic thought that he could replace it with a neopteran style until we had the motor apart and his neoprene seal had the" VEE" shape with the flat bottom which I later leaned is a 1958 -283 and up improvement. He used a Chinese finger and packed the new rope seal properly and left the extra length required amount, and it worked out and never leaked. Someone told me that they now make a rope shape neoprene one and was wondering if this is better seal?
    Last edited by nomad; 02-24-2019 at 06:19 AM. Reason: corrections

  5. #5
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    The change to the old school vat cleaning is the caustic material used in the vat. It's been outlawed by the EPA - the waste is too hazardous.
    Again, just take the block to a full service automotive machine shop and they will clean it properly.

    The replacement rear main seals that convert to neoprene are superior to the old rope seals and are easier to install successfully.

  6. #6
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    I put the seal in a 57 283 and it works great.

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