thermostat housing

Discussion in 'Original Drivetrain Topic' started by RS70Z28, Dec 8, 2006.

  1. Budz

    Budz Veteran Member Lifetime Gold Member

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    I've got a few '660's.....number's are on either the flange or the neck. :confused: Also, the "size/font" of the number's is different from one to the other.
     
  2. Gary S

    Gary S Administrator Lifetime Gold Member

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    Bud,
    I have a number of 660s also. Mine all have the number on the neck, but the ones that came off original engines have larger size numbers than the ones I purchased over the GM parts counter many years later.
     
  3. CamarosRus

    CamarosRus Veteran Member

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    I honestly thought that 660 was the (most/only) correct number, but I MUST defer to my fellow expereinced friends and judges.............after SEEING Jack's ORIGINAL, UNRESTORED, UNMOLESTED 70 Z-28.
     
  4. 70 LT1

    70 LT1 Member

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    My Norwood 70Z also has the same one Jack shows on his. I had assumed it was wrong until I questioned Jack earlier what was correct.

    John
     
  5. LT1Z28

    LT1Z28 Veteran Member Lifetime Gold Member

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    Could this be a case of mid year change ? It would be interesting to see if the build date determines what is correct. My car is a 2C and has the "660" on the base just like Jacks "2128". The 660 was definately used on the 1969 Camaro so having some of those left around for the 1970 was certainly possible. Happy Holidays to all.
     
  6. M21RSZ28

    M21RSZ28 Veteran Member

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    Correct Thermostat Housing For A 1970 Z28

    Here is a little history on the 660 and 128 water neck

    The 3877660 Thermostat Housing was first used in 1966 on Corvette's Chevelle's Nova’s and Impala’s

    There are at least six different casting designs for the 3877660 housings used from 1966 thru 1973 with no part number change at all

    Several different manufacturers produced the 3877660 Thermostat Housing during the 1966 thru 1973 production model years with several of the housings having different casting designs used at the same time during assembly line production in a single model year

    The early 3877660 water necks had the 660 casted on the base of the housing with some minor casting differences from 1966 thru early 1969 Production model years

    Also during the 1968 and 1969 model years the 660 water neck with the small lettering casted in the neck was used in assembly line production along with the 660 water neck with the part number casted on the base

    The 1968-73 660 water neck with the part number casted on the neck had some minor casting changes made in 1970 and again in 1972

    Original 660 thermostat Housings used during the 1970 model year used both small and large lettering casted in the neck with some minor casting differences between the two housings – again more than one manufacturer producing the 660 housing during the 1970 Production Model year

    Later GM service replacement 660 housings from the 1980's thru the 1990's use a new casting design with a thicker and solid base without recessed area’s much like the 128 housing and are different from the 1966-73 660 style housings and are incorrect for 1966-73 restoration projects

    This explains the differences found in the housings with numbers casted on the base of the housing or with small or large numbers casted on the neck of the housing

    The 128 Thermostat Housing was designed with a thicker bass for added strength with only one shallow recessed area near the tall bolt hole tower and this is probably why this housing was used on the 70 Z28 Camaro for the added strength on high revving small block motor

    The 660 housing base uses a thinner thickness base between the short and tall bolt hole mounting towers and also has three deeply recessed areas around the base of the housing making the base on the 660 not as strong a base as the 128 housing has

    The 660 water neck was used heavily in production during 1966-73 on V-8’s and was also available as the only replacement water neck for 1966 and later V-8’s - this makes the 660 very plentiful and an easy housing to use as a replacement for the128 housing that was used only on the assembly line during production and not sold as a service replacement part

    GM Parts catalogs are great and I use them a lot – however some parts listed in GM parts Catalogs are service replacement parts only and may use a different part number and a physically different part from the original part during production on the assembly line

    GM would scale down the number of parts used only on the assembly line and pick one of the several similar parts and use that part and part number for service only in the Gm Parts Catalogs

    Some parts on Z28 Camaro's were used on the assembly line only - for example the water pump pulley used on a early production 1970 Z28's is 3947824 also used on 1969 L78 SS 396 Camaro's

    GM used the 3976060 water pump pulley on 1970 LS6 and L78 Chevelle’s but also used
    The 060 pulley as the service replacement pulley in the 1970 parts Catalog for 69 SS 396 L78 Camaro and the 1970 Z28 Camaro’s and does not list the 3947824 pulley for the 1969 SS 396 Camaro’s or 1970 Z28 Camaro's at all

    So the 3972128 Thermostat Housing used on the 1970-72 Z28 Camaro’s and on the 1970-72 Lt-1 Corvette’s would never be listed in the 1970 or later Chevrolet Parts Catalog

    A very good friend has an original 1971 Z28 Camaro built in January 1971 and is an excellent example of an original Z28 Camaro with the correct original parts

    His January 1971 built Z28 Camaro retains the correct 128 Water neck along with such other rare parts as the Correct 064 Dated clutch Fan and Diverter valve with “GF” label and all the original GM hoses with the GM part numbers and the very yellowed white stripe vacuum hose - just some the very rare and hard to find original parts that make up an original Z28 Camaro

    The only way to verify the 1970-72 Z28 Camaro’s used the 3972128 water neck is by an Original Car - but this can be a problem also

    If you are not real familiar with original parts used on 1970 Z28 Camaro’s the parts you are looking at may look correct to you and you may assume the parts are original to the car - but the part could have been changed out and still look correct and original

    There are still some very original cars out there and they are the best source for what part is correct for your Z28 Camaro and yes as always GM would use other related parts in place of the standard part commonly used on a particular vehicle either by choice or by mistake

    Hope this answers the Question on the 128 vs. 660 water neck issue
    M21RSZ28
     
    Last edited: Dec 24, 2006
  7. iroc875sp

    iroc875sp Member

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    Wow, great info.... Thank you sir !
     
  8. 70 SS/L78

    70 SS/L78 Veteran Member Lifetime Gold Member

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    Thank you for the great info M21RSZ28.... Based on this statement i'd say that the value of a 128 water neck just went up!!
     
  9. camaro gold z28

    camaro gold z28 Veteran Member

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    Just found this photo of the of the original water neck from the 70 Z28 I am restoring. It is the "660" part number. The small bolt has a "C" marking and the long bolt has a "D" marking. Note the original orange over spray. The intake had a lot of over spray on the front and rear areas and in places it looked like silver paint was used to cover over some of the over spray areas.
    Anyone with unrestored cars find over spray and silver paint to cover???
    Thanks

    jon

    [​IMG]
     
  10. jacsey 70Z

    jacsey 70Z Veteran Member Lifetime Gold Member

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    Great Picture Jon, Intakes were on when the block was painted, hard not to get overspray on the intake. Guess it just depended on the guy spraying how messy he was as to the amount of silver. I've told the story of the guy I met that painted engines for 30 years at the Flint plant, he actually gave me the name of the guy at the end of the engine line with a can of silver paint and a brush touching up the intakes.
    My car has all kinds of silver (see pic) just about every intake bolt has silver on then also.
    Jack


    [​IMG]
     

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