Greetings New to this form postings . My experience with 35 years in the phosphating business and a Camaro restorer that Zinc Phosphate is 3 times less expensive that using manganese in the long run . Both carry the Mil Spec rating of 500 hrs or 5% salt spray resistance . I would be safe to think GM used the less expensive solution . Using the Phosphate search engine . I arrived at your thread . Todays problem is the shortage of nickle a element used in Zinc Phosphate is in short supply and GM has resorted to Manganese for replacement parts . I know replacement hood hinges were recently sold by GM with Manganese possibly where the confusion started They originally came with Zinc Phosphate in the 60s 70s If anyone has a old red copy of the 8000 group section of the old counter parts book It is possible to look up the assembly fastners used during final assembly . As you know every part to a 69 Camaro for example was listed in the parts book at one time , including the fasterners . My old dealer had one of those books .Example . Gr.xxxxxx Bolt ,Fender, apron, 5/16 Cap screw .finish Z . Now for Mix ratios : Zinc is used a 3% by volume with water and manganese is used at 10% by volume with water . A substantial increase in cost over the Zinc .It should be noted a good grade of Zinc phosphate will produce a very dark finish on fasterners .A Camshaft of ring & pinion grade of zinc does not need the nickle since it is break in only & produces a very light color gray on bolts & fasterners .The final color depends on the nickle content and the base metal content of the fastner being phosphated .I supplied the phosphates for the examples in Hemmings motor news restoration article by In line Tube Thanks for letting me rant.CamarosRus said:
Smog Diverter Valve Muffler Color on 73 & 74 Z28
- Thread starter 74Z28GC3
- Start date
This site may earn a commission from merchant affiliate links like Ebay, Amazon, and others.
Buckwheat, is your first name Vernon?
