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Oh, I know. I never had this problem before, but I have never rebuilt an aluminum block before either. We already covered this topic several months ago, and came to the general consensus that the cam tunnel was not perfectly straight. The "fix" for this was to hone and polish the bearings a hair. It made the cam fit snug, instead of getting stuck. That one bearing might have a little more clearance on that one side where it wasn't perfectly aligned, but it's not going to kill all the oil pressure. It would be like running a slightly wider bearing gap. Many people do this with main bearings, and don't lose oil pressure. It's not an ideal situation, but it seems to work. Like I said, this machine shop has done this lots of times before, and no one has complained.
ok, maybe it’s the missing plugs or valves in the oil pan like previously mentioned?
Travis, FIP cam bearings (finished in place) are common in most automotive OEM blocks these days, as part of the manufacturing process. FIP cam bearings are pressed in place and they are final reamed, along with block decking, honing cylinders, etc. It’s a part of the machining process before the blocks are sent out to be built. Where many guys make mistakes, is that we A$$ume that we can knock out a set of OEM bearings, and install a new set of cam bearings, and everything is going to be ok…should be simple right? But it’s not some of the time.
The manufacturers found that it’s far cheaper to cast a block that’s close to perfect, and then utilize final machining processes to “clean up” casting flaws. Basically the FIP cam bearings take up the “not so perfect” cam bearing bores slack by being final machined or reemed. The hone process isn’t used because using a true hone would embed debris In the bearing surface, so they are reemed. Not every block has cam bore alignment issues, so it’s fairly uncommon to find one where issues are present after new bearing install, such as the OP is seeing here, but it does happen. You can research Mahle cam bearing info and read up on the process, and how the OEM’s are doing this.
Another example of the blocks being “close but no cigar” is look at most LS aluminum blocks with the heads off, and you’ll see the cylinder bores are usually offset among each other. The liners are set in jigs and the aluminum is poured around them at the foundry. The cylinders are usually pretty bad out and final machining finds the exact bore centers, making some of the liners walls much thinner than the opposing wall, because of core shift.
Here’s a good read on FIP bearings…https://enginepro.com/camshaft-bearing-fundamentals/
Travis, FIP cam bearings (finished in place) are common in most automotive OEM blocks these days, as part of the manufacturing process. FIP cam bearings are pressed in place and they are final reamed, along with block decking, honing cylinders, etc. It’s a part of the machining process before the blocks are sent out to be built. Where many guys make mistakes, is that we A$$ume that we can knock out a set of OEM bearings, and install a new set of cam bearings, and everything is going to be ok…should be simple right? But it’s not some of the time.
The manufacturers found that it’s far cheaper to cast a block that’s close to perfect, and then utilize final machining processes to “clean up” casting flaws. Basically the FIP cam bearings take up the “not so perfect” cam bearing bores slack by being final machined or reemed. The hone process isn’t used because using a true hone would embed debris In the bearing surface, so they are reemed. Not every block has cam bore alignment issues, so it’s fairly uncommon to find one where issues are present after new bearing install, such as the OP is seeing here, but it does happen. You can research Mahle cam bearing info and read up on the process, and how the OEM’s are doing this.
Another example of the blocks being “close but no cigar” is look at most LS aluminum blocks with the heads off, and you’ll see the cylinder bores are usually offset among each other. The liners are set in jigs and the aluminum is poured around them at the foundry. The cylinders are usually pretty bad out and final machining finds the exact bore centers, making some of the liners walls much thinner than the opposing wall, because of core shift.
Here’s a good read on FIP bearings…https://enginepro.com/camshaft-bearing-fundamentals/
yes, I read up on this before posting. I’ve built a few engines in my lifetime and never had to hone a cam bearing. But, I have mushroomed them and the cam didn’t want to spin. Now, knowing what I do know, I knocked them out and installed new ones being more careful.
I was aware that the Oem’s would final machine the cam bearings in some blocks, but I knew that’s not what happened here with this block, I assumed his machine shop did not have a high dollar machine like oem’s use. I had also read about grit getting embedded in the bearings (highly probable) and then possibly messing the cam up. I’m not entirely certain that the cam bearing honing is his issue. Heck, I don’t think he’s even started it yet. When I built the motor that’s in my car now, I turned it over with the starter and it did not build pressure using just the starter. It may be fine if he cranks it. But be warned, if it does not have pressure in just a couple seconds, better shut it off or he’ll be pulling it back out and replacing bearings.
Travis, FIP cam bearings (finished in place) are common in most automotive OEM blocks these days, as part of the manufacturing process. FIP cam bearings are pressed in place and they are final reamed, along with block decking, honing cylinders, etc. It’s a part of the machining process before the blocks are sent out to be built. Where many guys make mistakes, is that we A$$ume that we can knock out a set of OEM bearings, and install a new set of cam bearings, and everything is going to be ok…should be simple right? But it’s not some of the time.
The manufacturers found that it’s far cheaper to cast a block that’s close to perfect, and then utilize final machining processes to “clean up” casting flaws. Basically the FIP cam bearings take up the “not so perfect” cam bearing bores slack by being final machined or reemed. The hone process isn’t used because using a true hone would embed debris In the bearing surface, so they are reemed. Not every block has cam bore alignment issues, so it’s fairly uncommon to find one where issues are present after new bearing install, such as the OP is seeing here, but it does happen. You can research Mahle cam bearing info and read up on the process, and how the OEM’s are doing this.
Another example of the blocks being “close but no cigar” is look at most LS aluminum blocks with the heads off, and you’ll see the cylinder bores are usually offset among each other. The liners are set in jigs and the aluminum is poured around them at the foundry. The cylinders are usually pretty bad out and final machining finds the exact bore centers, making some of the liners walls much thinner than the opposing wall, because of core shift.
Here’s a good read on FIP bearings…https://enginepro.com/camshaft-bearing-fundamentals/
so I ended up reading most of it. It agrees with what I’ve been saying. And I also like this idea:
Honing is not recommended because grit from the hone stone will become embedded in the bearing surface. A homemade reamer can be made using an old camshaft if the journals are still within spec. Cut a groove diagonally across each journal about 1/8” deep. Then relieve the journal surface on one side of the groove, leaving the other side sharp. This produces a single flute reamer that can be turned with the aid of an old cam sprocket to remove bearing metal from the high or tight spots.
so I ended up reading most of it. It agrees with what I’ve been saying. And I also like this idea:
Honing is not recommended because grit from the hone stone will become embedded in the bearing surface. A homemade reamer can be made using an old camshaft if the journals are still within spec. Cut a groove diagonally across each journal about 1/8” deep. Then relieve the journal surface on one side of the groove, leaving the other side sharp. This produces a single flute reamer that can be turned with the aid of an old cam sprocket to remove bearing metal from the high or tight spots.
Yessir. My machinist has one of these cams that a previous employee made while there. He told me it was around there somewhere a couple months back, so when I dropped my recent build off earlier this week, I asked him if I could buy it from him. It’s a brilliant idea. I’ll make my own if he doesn’t sell it to me.
Yessir. My machinist has one of these cams that a previous employee made while there. He told me it was around there somewhere a couple months back, so when I dropped my recent build off earlier this week, I asked him if I could buy it from him. It’s a brilliant idea. I’ll make my own if he doesn’t sell it to me.
That’s what my machine shop did to mine. I know I said “hone”, but they used a stock cam as described above. It barely takes anything off. That’s why I call it a hone. Sorry if that caused confusion, but I didn’t want to derail the topic of this thread.
I ordered a 2 pack of plugs from Amazon. I’m going to plug the oil pan and try again. I just need it to work one day. After the dyno, the oil pan is coming back off. I have to swap oil pans with the LS1 that is still in the car, and also losing oil pressure.
Ok, I installed the plug in the oil pan. I got a 2-pack in case I ever need to do this again. I also put the oil pump back together and bolted it on the engine. That's when I noticed the problem. This is one of those, "I can't believe I didn't notice that" kind of moments. I'll just post the pics and let you see for yourself.
Oil pan plug Oil pan plug That's where my oil pressure was going!
I ordered the 9427693 plug from a local Chevy dealer. It should be here in a few days.
I got the spring style tensioner because it was listed as a fit for my engine. I looked at several of the "block" style timing chain dampeners, but none of them listed the 6.2L as a compatible fit. I didn't think there was a difference in hole pattern. I don't know why there are no 6.2L engines listed as a fit. The first 2 gen-4 engines I took apart still had the original spring type tensioner, and they were still functional. This engine was already disassembled, so I don't know what kind of shape the tensioner was in. This won't be a high mileage engine, so I'm not worried it.
I ordered the 9427693 plug from a local Chevy dealer. It should be here in a few days.
I got the spring style tensioner because it was listed as a fit for my engine. I looked at several of the "block" style timing chain dampeners, but none of them listed the 6.2L as a compatible fit. I didn't think there was a difference in hole pattern. I don't know why there are no 6.2L engines listed as a fit. The first 2 gen-4 engines I took apart still had the original spring type tensioner, and they were still functional. This engine was already disassembled, so I don't know what kind of shape the tensioner was in. This won't be a high mileage engine, so I'm not worried it.
The LS2 style has a bolt spacing of roughly 1.7 inches. It was the LS1 that had a wider pattern and is obsolete. I think it was around 2.185
The spring tensioners were designed for engines with VVT, as cam timing from a firm chain is imperative in a VVT application. Did some engines get the spring tensioners that didn’t have VVT? I’ve never seen one personally. I buy aluminum blocks, and do a fair amount of high end LS builds for clients. Sometimes I’ll buy a core for the block and if it’s a VVT engine, it will still have the spring tensioner in there. I’ve tore a lot of those down and the tensioner is broke, and the spring from it is in the oil pan…it’s common. I’ve had a couple where the failed tensioner caused undo wear on the chain, from the chain rubbing on the steel frame of the tensioner, and the chain is broke. Save yourself the trouble and buy the LS2 damper block. It’s stable and does a good job at keeping chain harmonics down. It’s fits your block, zero issues. Here’s a pic from one of my builds…
I got it plugged up, so it should make some pressure now. I also slid a couple washers under the oil pump spring for good measure. I already have the spring chain tensioner in there, and I'm not replacing it now. I appreciate the input, but I'm not replacing it this far into the build. I'll keep it in mind for the next build, which will likely be the LS1 that's in my car now.
Ok, I installed the plug in the oil pan. I got a 2-pack in case I ever need to do this again. I also put the oil pump back together and bolted it on the engine. That's when I noticed the problem. This is one of those, "I can't believe I didn't notice that" kind of moments. I'll just post the pics and let you see for yourself.
Oil pan plug Oil pan plug That's where my oil pressure was going!
Are you saying there was no Welch plug in the oil galley??!!!
