Moose2 Posted August 27, 2022 Share Posted August 27, 2022 I just started tearing open a 425 I bought from a local boneyard. It sat in the open for several years without any heads although the valley cover, timing chain cover and oil pan were still on it. Oddly the bores don't look too bad and they mic at stock (no overbore) so I think an overbore might work out. However some of the valve lifter bores don't look good at a glance (rust issues). My question is: if I have to, is it possible to overbore the lifter boreholes and are oversize hydraulic lifters available?? Alternatively, is it possible to sleeve lifter bores?? Never said I was smart, just looking for a winter hobby and thought bringing a 425 back from the dead would be a worthwhile thing to do. Link to comment Share on other sites More sharing options...
Craig Balzer Posted August 27, 2022 Share Posted August 27, 2022 Gonna need some more details : Link to comment Share on other sites More sharing options...
gungeey Posted August 28, 2022 Share Posted August 28, 2022 Sleeves. http://bhjproducts.com/bhj_content/products/liftersleeves/lbs.php I think the cost dictates that the engine be of some significant sentimental or historical value. Hone the worst one and let's take a look. The bottom of the bore is probably fine. 1 Link to comment Share on other sites More sharing options...
telriv Posted August 28, 2022 Share Posted August 28, 2022 There is NOT enough "Meat" in the lifter bores to bore them out to an inch plus using the BHJ sleeves. MOST stock GM lifters are .842" in diameter. Now you could use a Ford lifter which is .872" in diameter. So all that the lifter bore will need to be enlarged is .015" for a total of .030". In any case the expensive/costly part is the fixture that will need to be CUSTOM made to be absolutely positive EVERYTHING is on center as it's supposed to be. Just my thoughts on the subject. Tom T. Link to comment Share on other sites More sharing options...
Moose2 Posted August 28, 2022 Author Share Posted August 28, 2022 Thanks everyone. I'll try to get a few pics to share, and I'll also clean up one of the bores that looks bad. More soon........ Link to comment Share on other sites More sharing options...
Moose2 Posted August 28, 2022 Author Share Posted August 28, 2022 One other thought in response to gungeey's post: even if the bottom of the bores are fine, aren't I losing some oil pressure anyway? I've never been real comfortable with the functional oil pressure limit of approx. 35# and hate to lose any of it if there's a better alternative........ Link to comment Share on other sites More sharing options...
gungeey Posted August 28, 2022 Share Posted August 28, 2022 1 hour ago, Moose2 said: One other thought in response to gungeey's post: even if the bottom of the bores are fine, aren't I losing some oil pressure anyway? I've never been real comfortable with the functional oil pressure limit of approx. 35# and hate to lose any of it if there's a better alternative........ Have to clean it up and see the extent of corrosion. You have a couple lifters that were at the bottom of their travel. They'll bleed out quicker than the restwhen you shut down. They may be a little noisy at start-up. That's the route I would take for a winter project. As Tom said there's not a lot of meat to over bore. BHJ makes sleeves of oilite brass. Hardest to find is an experienced machinist with the patience for the multiple setups/passes required. Time= Big $$$$. Link to comment Share on other sites More sharing options...
Moose2 Posted August 28, 2022 Author Share Posted August 28, 2022 Here are two pics of the worst looking lifter bore. In Pic A its the hole on the left before I took a quick pass at cleaning it up this morning. In Pic B its the hole at the top of the picture, and I was impressed at how well it cleaned up. Behind the oil port in the bore you can see a glimpse of the lower part of the bore and it isn't cleaned up well, but that's because I didn't put a lot of effort into doing a complete job; just wanted to do a quick partial shine to see if the corrosion was limited to the surface of the bore or had eaten its way deeper. I'll take it to the machine shop and hope they don't find a show-stopper in one of the bores. If they do, I'll probably take your advice and walk away from it as a project. Thanks to all of you for sharing your knowledge with me! Mike Link to comment Share on other sites More sharing options...
arnulfo de l.a. Posted August 28, 2022 Share Posted August 28, 2022 Best way to know for sure is to measure but looking at the pics ,if that s the worst as you state I think you will be alright with cleaning pass only. I did not see any pits only surface rust. Link to comment Share on other sites More sharing options...
JZRIV Posted August 30, 2022 Share Posted August 30, 2022 (edited) The lifter bores can be sleeved but you'll need an experienced shop that specializes in bringing engine blocks back from the dead and has done that process. Custom sleeves can be made. Tom T is right, there isn't a lot of metal there in the bosses but I don't think there is a lot of lateral load on them either. Since its a 425 its worth investigating further. After they are cleaned up you'll know what lies ahead. Having said that.....The first thing I would do is have the block magnafluxed to check for cracks in water jacket Edited August 30, 2022 by JZRIV (see edit history) Link to comment Share on other sites More sharing options...
RivNut Posted August 30, 2022 Share Posted August 30, 2022 Wild hair here. Can you clean up the lifter bore and find a lifter from a different application that would fit the new diameter? Link to comment Share on other sites More sharing options...
telriv Posted August 30, 2022 Share Posted August 30, 2022 Already been discussed Ed. Link to comment Share on other sites More sharing options...
Moose2 Posted August 31, 2022 Author Share Posted August 31, 2022 I took it to the machine shop yesterday and they'll magnaflux the block, take out the frost plugs and oil gallery plugs and run it through their cleaners. I asked them to run it through the cleaning process twice. Then they'll check the decks for warping. If it isn't pronounce dead by then, they'll hone the lifter bores lightly and mic them. If it still isn't pronounced dead, I'm gonna assume it can be run through their shop along with a set of magnafluxed and planed heads and I'll get it back as a decent long block............ This machine shop has a good reputation, been in business for decades and have rebuilt a different 425 nailhead and a Cadillac 472 for me in the past. 1 Link to comment Share on other sites More sharing options...
telriv Posted August 31, 2022 Share Posted August 31, 2022 Just make absolutely sure the lifter bores don't have too much clearances as you will end up with low hot idle oil pressure. I believe the spec is .001" clearance IF I remember correctly. Tom T. Link to comment Share on other sites More sharing options...
Moose2 Posted September 5, 2022 Author Share Posted September 5, 2022 Thanks Tom, I'll check that spec in the shop manual, and pay attention to it. I'll talk to the machine shop guys about it too......... 1 Link to comment Share on other sites More sharing options...
psychostang Posted September 25, 2022 Share Posted September 25, 2022 Any update on this? Link to comment Share on other sites More sharing options...
XframeFX Posted January 30, 2023 Share Posted January 30, 2023 Yes, any update? Link to comment Share on other sites More sharing options...
Moose2 Posted February 28, 2023 Author Share Posted February 28, 2023 Sorry for the huge delay everyone. The machine shop is moving at the speed of a glacier. They still have to line bore the crank holes and attend to the lifter bores. These guys are friends and I'm trying to maintain that so their speed is my speed. Not many alternative shops in the area either....... When I know more, you guys'll know more!!!! 1 Link to comment Share on other sites More sharing options...
arnulfo de l.a. Posted February 28, 2023 Share Posted February 28, 2023 2 hours ago, Moose2 said: Sorry for the huge delay everyone. The machine shop is moving at the speed of a glacier. They still have to line bore the crank holes and attend to the lifter bores. These guys are friends and I'm trying to maintain that so their speed is my speed. Not many alternative shops in the area either....... When I know more, you guys'll know more!!!! You may want to rethink the line bore if you have not done it yet. Russ Martin advises against it. Leaves the timing chain permanently loose. 1 Link to comment Share on other sites More sharing options...
telriv Posted March 1, 2023 Share Posted March 1, 2023 I agree with the above. NO LINE BORE. If the caps are properly torqued down you will see that Buick's machining was pretty good. I haven't had to do one yet. For most machinists it actually takes more time to measure than do the boring. To me it's a lazy way out. Just my thoughts on the subject at hand. Tom T. 1 Link to comment Share on other sites More sharing options...
Moose2 Posted July 4, 2023 Author Share Posted July 4, 2023 Huge time delay, but still moving slowly. The machine shop cleaned/honed the lifter bores and found them acceptable. I told them to skip doing a line bore so that's behind us too. They planed the top deck on the block 10 thousandths, and the heads needed to be shaved by ten as well. Crank cleaned up fine but needed to be ground - 10 also. Piston bore is 30 over; I was expecting that. They're using Clevite shell bearings throughout. I'm adapting a switch-pitch trans from a '66 and the flex plate I received had been drilled "mirror image" to the stock mounting bolt pattern. The machine shop stalled out on getting it mounted in order to balance the rotating assembly, and were grinning at me when I went in to apologize for the flub. Took about 90 days just to get a replacement for the darned thing. I think they're still shaking their heads at me down at the machine shop. Just waiting on valves, guides (not bronze) and springs now. Russ Martin will be refurbing the rocker arm assemblies. 1 Link to comment Share on other sites More sharing options...
telriv Posted July 5, 2023 Share Posted July 5, 2023 The assembly gets balanced with the harmonic balancer & the flex plate bolted on. The flex plate can mount six different ways & ONLY ONE way is correct as all the bolt holes are symmetrical. The index holes NEED to line up or else they will never be able to balance the crank correctly. Tom T. Link to comment Share on other sites More sharing options...
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