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#21
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Something to consider since the block is coming back down. This would not be a big deal. You can have the bushings knocked out. Drill a .030" hole in the bushings to line up with the oil feed hole in the block. Drill this hole on the other side of the giant hole. Put the same bushings back in. Flat stone hone those bushings to fit .904 Crower lifters. The only cost would be a little labor. Really not that bad of a fix.
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#22
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Concerning lifter bushings: One of the most popular manufacturers is BHJ products for them. The most common size for GM engines is 1.002". This would be a .160" larger hole than stock or .080" wall removal. Looking at that Ram Air V block picture, doesn't look like an issue at all. BHJ will make bronze bushings any size you want in .001" size increments inside or outside. They have two different hardness bushings available. Custom bushings are around $20.00 each. They all need to be honed after installation. They get out of shape during installation.
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#23
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I would be very concerned with trying to doing any sort of home honing work to size the bushing when running roller lifters and there need to be perpendicular to the Cam.
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I do stuff for reasons. |
#24
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Although the lifter bore hone procedure could be done at home, it is very messy. You need a constant bath of honing oil to get good results. Generally done in the cylinder hone cabinet at a machine shop. Precision, flat stone rigid hone is an expensive tool. Mine was around $1200.00 10 years ago. I would guess the tool is in the $1500.00 range now. It will produce , straight round bores though. As far as proper bore geometry to the crankshaft/camshaft centerline, hopefully the original bores were bored with a squaring fixture for that purpose. Again the tooling is made by BHJ and called "Lifter True". The work is done in a vertical mill with the fixture. The fixture is engine platform specific. They are about $3500.00 for a basic kit, plus an additional $1000.00-1500.00 for each engine platform you want to use it on. Without a fixture like that, the only way to get the bushings in correctly would be to have a CNC lifter bore program for a 5 axis machine. Actually, could be done on a 3 axis machine if you had one and a program for a Pontiac. It's a big job either way.
I would not recommend sizing anything with a ball or flexible hone. http://www.bhjproducts.com/bhj_conte...ooling/lbh.php |
#25
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So when finishing bushings, you just go straight to the hone and no reamer?
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#26
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That depends on the shop, the tooling they have, and the ID of the bushing. Reaming lifter bushings is really a tough job. Especially if doing it by hand. Honing is super slow, but accurate. When I have BHJ make my bushings, I size them so I don't have to ream them. I go for a .002-.0025" press fit. I try to have the ID about .004-.005" small once installed so I can just hone them. Honing from the OP's .842" nominal size to a .903" would take hours and probably wear out a set of stones. In his case, I would ream or drill them if I wanted to reuse those bushings. He would need to see if his shop has 2-4 incremental reamers to do this. Can't ream .060" in one shot. There is allot of advanced tooling and cnc processes out there. I have no idea what his shop may have available. In my minimal old school shop, we have a vertical mill and a rollover fixture. Plus the BHJ tooling. If I was reusing his bushings, I would have to drill the bushings within a 64th of an inch. Then hone the rest of the way. Or he can just start over. He can save a couple hundred bucks if he reuses them and they can be saved.
Last edited by mgarblik; 03-30-2023 at 06:05 PM. |
#27
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Thank you for the follow up.
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#28
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Out of curiosity could a set of lifters have the outside diameter hard chromed to buildup the OD? I'm not sure if anyone has tried this?
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Todd Sedlmeier Who ever thought pinewood derby cars would lead to this! October 2004 HPP Shootout participate http://www.highperformancepontiac.co...out/index.html 86 Grand Prix 535 High Port 8.93 @ 153 65 GTO 433 High Port 12.04 @ 113 |
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