Building a GMC 702 V-12
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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? | 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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| + | On with assemble, the "keeper" of this ball and spring is a tight fit on the HL-18 (and originals) to the point of requiring a small screwdriver to drive the "hat" edges into the back side of the plunger piston. I noticed that while disassemble of originals that some were not fully seated and that the other part numbers did not have any means of retention as the "hat" is of smaller diameter. I would guess that not using a retained would make it difficult to insure the ball did remain in proper position relative to the orifice at the plunger bottom. Hence a malfunction during operation as this spring would no interfere with the proper operation of the tappet. | ||
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| + | [[File:keeper assemblyr.jpg]] | ||
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| + | The photo above shows the keeper properly seated (ball in orifice, small spring and keeper) in the plunger bottom. Now we are ready for assembly of the lifters. By this time all parts have been thoroughly cleaned in solvent based parts washer (remember when it used to be cheaper to use gas to wash parts, invest in a commercial parts washer service... its worth it) and then rinsed in kerosene. That's right, kerosene for reassemble. Oh, actually prior to the setting of the orifice ball it is a good idea to trial fit all the plungers with the mating lifter bodies. DO NOT MIX these up as there are factory matched. Generally if they bind you will need to take some crocus cloth and polish the spot of interference. Remember that if you force them then they will scratch which will make the whole thing worse. Your gonna want that plunger to slide smoothly into the body. While I am on this whole smooth thing, if you bought NOS lifters on evil bay or somewhere else they still need to be disassembled and cleaned. Several I found were rusted from age and moisture. To get them apart I simply removed the top retaining ring, squirted Kroil into the side port hole and taped it vigorously against a heavy vise, pushrod end doing the impacting as the plunger came to the edge of the body. | ||
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| + | Next thing that happened, I found out what those springs are for. It is an attempt to prevent bleed down during period of non operation. As this thing is so large and the oil path long, I got an idea that the engineers were trying to prevent premature wear (ala poor lubrication on the cam lobes) by holding a good amount of oil in the lifter body. At least it would mean having pressure come up faster if you did not have to pump half a quart of oil into the lifters. Anyway, you can not assemble anything unless you relieve the trapped air under the plunger. | ||
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| + | [[File:assembly trickr.jpg]] | ||
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| + | This is how I did it with an awl. | ||
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| + | [[File:togetherr.jpg]] | ||
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| + | Assembled!!!!!! | ||
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| + | [[File:completed liftersr.jpg]] | ||
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| + | That's a lot of lifters.... | ||
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| + | Of course there are a lot of holes to fill. As mentioned in the start of this article, I am only going to cover the "odd things" that one needs to pay attention to and not normal assembly. If there is interest, I can post another section or new WIKI and the run of the mill tear down check and rebuild. | ||
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| + | So here is the short block.... Motor City's greatest RPO gas motor of all times. | ||
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| + | [[File:702 Short Blockr.jpg]] | ||
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| + | Note the difference in design of the lifter galley. More to come..... heads next and that is just as interesting, right down to the sodium filled valves. | ||
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[[Category:Engine]] | [[Category:Engine]] | ||
[[Category:Good articles]] | [[Category:Good articles]] | ||
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