Building a GMC 702 V-12
(→Hydraulic Tappets) |
(→Hydraulic Tappets) |
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[[File:HL-31 compared.jpg]] | [[File:HL-31 compared.jpg]] | ||
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| + | In the picture the lower set if the used V-12 (by the way the wimpy little clip is removed with just a small screw driver and if the assembly does not easily come apart it will if you rap it against a hard solid surface like a vise or anvil) and the GM manual wants you to clean them with kerosene. Pay attention here because this is where the difference is. Notice the ball and retainer in the upper new HL-16 is free floating and in the V-12 there is a little spring that keeps in contact with the plunger body orifice at the bottom center of the plunger. These parts are easily cleaned and but into a new plunger and body. All of these lifters I have been showing have the same external dimensions in case I did not mention that up front. In the example of the above picture then I simply used the Old push rod cup, ball spring and ball retainer. | ||
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| + | Here are the parts I shall put together effectively the a new plunger, ball and body. Oh yes and a new wimpy retainer. I think I may regret not putting some high quality snap rings in place of these. The original motor had plenty of these broken and or well worn. | ||
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| + | [[File:Build.jpg]] | ||
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| + | So a closer look at that spring and some contemplation | ||
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| + | [[File:Curious spring.jpg]] | ||
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| + | What is the purpose of that spring? I did find that the HL-18 is the lifter that matches 100% including this spring. I summarize that it to help prevent bleed down of the valve train when sitting for long periods. It would take a while to fully pressurize 24 empty lifters this large. Comments are welcome and I will also get a full PN listing though I tell you that I have three distinct lifters with the same part numbers as the HL-16 and older not HL series are by the book of numbers replaceable. Back to that spring thing, what would happen if one uses the HL-31 without it? | ||
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