Don't forget Sean, he has a '68 engine, the first year sbb 350 that IIRC has even smaller oil passages than the later year sbb 350 engines? Didn't the General open those up later or was that just for the later v6 engines? Either way, if in the General opened up the v6 engines after 1980 then they would of for the sbb 350 if they were still in production. So I would say the mods that aren't hard to do, are still worth doing with the block taken down that far anyway. So why talk the guy out of doing them?
The closer to 'blueprint' specs you can build an engine, the better, but since it's not a racing engine and will probably never see north of 5500, much less beyond 6000, bearing tolerances don't need to be spot-on perfect either. With adequate oil pressure and volume, even tight specs will get enough oil, and loose specs (all this considered to be within the tolerance spectrum--not too far out in either direction) will have enough oil cushion. Crankshaft flex shouldn't be too bad using original factory stuff with a 2000-5000 nominal powerband range. This may not be a popular view for professional race engine builders, but if it were mine and the scoring on the crank journals weren't too bad (beyond the tolerances you'd see within the acceptable bearing clearance spectrum), I wouldn't even grind it at all and just put a fresh set of bearings in. What this means is you have to measure the highest point on the crank journal and compare it to the deepest recess of the scoring, and if that difference is equal to or less than the tolerance considered acceptable within the bearing tolerances themselves, then on a standard rebuild that won't see high RPMs won't hurt a thing. Get other opinions on this, and if I get a few red flags on this suggestion, then disregard it. Resources are limited as well as access to goods and services that are readily available here in the USA, so we all need to weigh in everything before offering a potential prognosis. I think you'd all be shocked if you were to tear down every older engine and measure specs that were considered acceptable from the factory, and inside engines that lived for decades like this lugging around heavy cars (and guaranteed they weren't babied the entire time). With that oil pickup tube almost completely plugged up, it still didn't spin any bearings. These Buick engines are rugged beyond belief. You can take factory parts and tweak them with a few changes or added induction and double the power output on them with little to no adverse effects on engine durability. Realise what you're dealing with here. I would certainly do some 'massaging' in areas that look like they might need a helping hand, such as oiling journals that bearing orifices don't line up perfectly with, chamfer where you can, etc. If it still turns out you need to mill your crankshaft, then listen to 8ad-f85. He's a pro with oceans of knowledge and won't steer you wrong. Once you start modifying the original components, things need to be measured and changed to accommodate. As usual, more 2c from the resident eccentric thinker Thanks for the compliments, by the way. You seldom see that sort of thing without a huge portfolio of parts and monies spent on something. haha (no offense intended to anyone)
oh-oh... so there's more to it then what I thought. I wasn't planning on boring out or anything... I thought I could just ground the cam and get oversized bearings to compensate for that. The only thing that went to the engineering shop was the crank.... nothing else. The plan was to get it back, say with 0.010 off it and then get 0.010 oversize bearings and fit it all back together... in my mind I thought, take a bit off the crank, add a bit on the bearings, the crank would still be working in the same place that it was before. No money in my pot for all that kind of engineering work... not even for labour as I'm doing it all myself. the crank grind is the only thing being done somewhere else. guess will be a case of putting it all back together, run it for a while and get rid of it.
The later v6 engines were also slated to be used with turbos, and so this mod would have probably been done across the board to those engines. I see no big deal with wanting to add extra insurance to the oiling, and since the mods are simple, why not? I posted what I did to demonstrate that factory oiling on stock engines was plenty good enough, and others have said that there were no issues with mild-moderate builds and no oiling mods. This is just to reinforce the idea that oiling will be fine either way, but again, who could argue with added insurance? IIRC, it was the big blocks that had issues with oiling moreso than the small blocks.
Bear in mind I'm not trying to change anyone's mind on anything, but just to offer up another point of view to be taken into consideration in the entirety of all information thus far added. Don't take my word as gospel, just another 'voice' in the crowd.
I know the later engines have a larger pickup tube but i am not sure if they also have larger internal passages i never measured... I have 7 bare blocks here i will measure them when i have a chance.. I just caution that if a person starts drilling out passages they need to be careful its easy to ruin a block...
Unless they changed the foundry tooling (expensive) or added in drilling out the passage as a standard machining procedure for mass produced blocks, it was probably a simple step up on pickup tube size to ensure better access to the oil in the pan, possibly due to issues with debris clinging to the bottom of the screen. lol (engineers have to foresee all kinds of possible obstacles the product may encounter during its expected lifespan) Higher compression (both static and dynamic, and not necessarily mutually exclusive) will affect bearing tolerances needs as well. Also higher RPMs, overall power output, and general strain/shock the bearings will see, including detonation, among other things. Most things tend to be over-engineered for these reasons, and as long as it falls within an acceptable tolerance spectrum, will live a happy life for its intended purposes.
I hope I didn't send the wrong message... It will live fine and go down the road within factory tolerance. (I think I mistyped the .0023"? Oh well) It's getting harder these days to get them to assemble without more corrective machining at the customer's cost. It's dern near an epidemic Taking .010" off isn't a certain way to ensure it will go even together. If you are uncertain why then re-read what I wrote about tolerances. Engines suffering abuse or victims of previous owners have it worse. The OP would have much greater challenges dealing with those problems being where he is. I do understand the idea behind low budget, just good enough to roll down the road builds. If I was being ultra "frugal", I would just put it back together with new bearings and not grind the crank if it were within .0015" round, taper and proved to spin freely by hand installed without the seals. It will run just fine. My point being...if you are going to machine things then why introduce any chance for problem? There's a reason this one's apart already.
the reason this one is apart was because I got valve clatter...and after inspecting the whole thing, it was due to low oil pressure. the rest of the engine was performing really well. the low oil pressure was due to a load of gasket stuck in the oil pickup, that restricted the oil flow heavily. - my own fault, when I imported it from the US I should have taken the sump off or at least fit an oil pressure light and gauge. So the truck has probably been running like this for the last 2 years... till recently when I kept revving it hard trying to figure out why it would not develop more speed at higher revs. so.. it happened due to my own stupidity. I still don't understand the whole grinding the crank thing you explained and I have read it 3 times now. I guess the only thing is tolerances.. they might gring 0.010 off the crank...and the oversized bearing not being exactly 0.010 oversized. But oh well.. I will live with it. Have no money for much more engineering, or love for the engine or intentions of keeping it for long years that will justify the cost. I do about 2k miles a year.. probably not even that, at cruising speeds, hardly push the pedal down hard. In parts I'm looking at $900 so far.. and £1k is the maximum I will be spending on this.
The aluminum small blocks also have oiling issues, I'm not sure if the block material makes a difference or not. But they need all the help they can get. A comprehensive and thorough approach generally gives quite good results though. When you are doing the build yourself there are a lot of little things that add up to a big difference. Blaming the low oil pressure exclusively on the crap on the pickup screen is a little short sighted I think, as that may not be the whole problem. Quite a lot of that screen is still clear, certainly an area much larger than the cross section of your pickup galley. Anyway, getting your crank grinder to meet your bearing clearance requirements should not cost any extra. That is part of the job. You get the bearing inserts, you take him the block, the bearings and the crank, and you tell him how much clearance you want. It should come back to you in spec if he's a competent machinist. But it almost sounds like you don't want to do the work to get the right results. Well, you don't have to put any effort into it I suppose, but most of us would feel kinda bad about slapping something together and foisting it off on an unsuspecting buyer. That's some bad karma right there. If you do want to do it right there are cheap ways to go about it. For instance, drilling out that pickup galley. You can buy a 12" long drill bit for about ten bucks. You can chuck that up in your hand drill and reduce the first 1/4-3/8" of it to the size of the existing hole with a pedestal grinder or angle grinder (a bench vise helps). You can then resharpen the cutting edges with the same grinder so it will cut (give it a small back relief so it can sink into the metal) and then voila, you have a piloted bit you can use with your hand drill which will not wander and break out to the side of the hole. It doesn't have to be perfect to do a decent job. That's one example, costs all of ten bucks. How can you reasonably pass that up? There are others. Yes you can slap it back together just the way it came apart but that's not the same as the way the factory built it. There has been wear in all sorts of places. Heat cycles have changed things. Just because it was OK from the factory does not mean it will be OK for you. And, lest we forget, many flaws were passed on in the hopes they wouldn't be noticed or just from hangover Monday. Upside down rings and crap like that, seen it many times. The factory was far from perfect. Jim
you cant see on the photo, the oil pickup tube was completely clogged with long bits of gasket, all that grey stuff you can see on the photo was all the way into the tube roughly 3" in... was so much of it in there that I couldnt even pull it out without breaking the gasket. Some of it is still in there. I did say I would do the oil modifications. can put it on my lathe or milling machine. it's all the stuff regarding to block that I won't be doing. crank will be ground, oversized bearings will be put in.. fingers will be crossed. I'm in the UK, not the US, things are not around the corner and are not cheap. the crank has to be sent over the post to an engineering place...can you imagine how much would be to send a block? So, as much as I would like to do exactly as you guys describe... cost is prohibitive. so I'll do the best money allows. Ok the way I'm doing it might not make the engine last 50k miles.. but hey.. I don't even do 2k miles a year...
That does mean more work for you of course. So, get your bearings, seat them in the block and torque the caps, then measure them to the nearest ten-thousandth of an inch in at least 3 places each. You have a lathe, you should have telescoping gages and micrometers. Same for the rods. Hope like hell they are all the same, and be particular about it. Everything rides on your own accuracy here. Now measure your crank and see what you have, based on that one bearing photo, .010" undersized may not be enough. But if it is, no deep grooves or such, subtract .001" from your bearing measurements and tell your crank grinder to meet that dimension +0, -0.0005" and ship it off. Measure it VERY carefully when it comes back. No reason to do much to the block if there are no hot spots on the bearings and the crank turns freely. Except for drilling out that pickup galley. That I'd do in any case. Some people say 1/2", some say 9/16", some say 5/8". Your choice there but the bigger it is the easier it is to suck oil through it. Means better oil pressure. My 340 is at 9/16" and has very good oil pressure but it has all the other oiling mods too. There was plenty of meat to go to 5/8 and I wish I'd done it, but it's your call. Little steps add up here, but the best thing you can do is get the bearing clearances right. Then stay the course and get the rest of it right too. Do a forum search for oiling mods. BTW, I've also used a lathe and gas torch to make drill bit extensions when I didn't have that long bit. Not hard. Jim
*To be more clear, yes the bearings may vary a slight amount. *The part of the block where the bearings rest varies slightly more, especially with wear and abuse. *When the crank is ground .010", it isn't ground exactly .010"...there's a range to that dimension. *All of these slight differences might stack up to a problem where they end up too tight, too loose, or destroying each other. *Actually, they often do and the problem is worse in recent years for several reasons. *Engine parts like blocks often warp slightly from use and abuse, making the likelihood stronger. *You can choose to do the same thing in a different order that prevents all of this from happening. *Measure twice, cut once
No there is no hotspots on any of the bearings, no discoloration anywhere either. I don't think the engine was too bad, I only had the rockers knocking and that was due to oil pressure.. everything else turned freely and beautifully... No tight spots, could easily turn the engine by hand (well not easy as in there's loads of slack, but with not much effort if you know what I mean). So I'm getting a bit confused. so say if the machine shop finds that grinding 0.010 is not enough to get rid of scoring (I believe it is as you can hardly pick it up with your nail), they can't grind just 0.015 right? they have to go more because the next set of oversized bearings are 0.020.... right? OK, I've read it properly now and I get it. I understand now why sending the crank, after getting the bearings. get new bearings, put them in, measure the inside diameter. then measure crank see how much of the crank has to be ground off to meet the inside diameter in the bearings. got that right? If that is the case.. its a difficult one. because I only have one shot at ordering parts. and they will only come in January. If I order 0.010 and they are not enough.. then i'm stuffed. Could I just order 0.020 and then measure the inside of the bearings, measure the crank, etc and tell the machine shop to grind the crank (even if more than required to clean the scoring) to match that? got this right?
Order both sets of bearings now as I've previously mentioned...or order the .020's right now. You'll need to have the bearing inserts installed and torqued in BOTH the mains the rods (all of them), in order to obtain measurement. Since you use lathe and mill, I'm going to assume you are comfortable obtaining measurements with mics and bore gauges. You'd have to have dang near a chisel gouge to not clean up @ .010". Even with as wide as the blade is on a caliper, there's no way you or the shop will get any useful measurement prior to grinding. They won't bother, they'll grind it and tell you where it will end up if you don't tell them your concerns. The problem with having them grind twice is that the rods are ground first and the mains second (it moves things around some). So it's way better to have them do it just once depending on what it is you are grinding. I know this goes against the grain here but bear with me... Since you are shipping things around and can't be there in person to resolve problems, it might be wise to have them grind some extra clearance...to the low side of the range or an extra .001" after you give them your dimensions. You can blueprint your oil pump gear clearance to give the best possible chance of success.
Maybe a mic of rod journal and light polish with a .001 bearing will do well for him. And how much of this stuff is same as early rover /215. ? Which should be available in Europe. https://www.summitracing.com/parts/cle-cb610p1 As far as overengineered on the oiling system, I would not hope there. A piloted 1/2 in drill bit then a long air craft bit. Or similar in Europe . Worth the cost of the drill bits and time . The oiling system is marginal at stock. Gary’s info is usually sound. But after a few builds and seeing the v6 “before black” being drilled by factory to 5/8 . I would not hesitate on drilling it out. My opinion differs from Gary’s on oiling. Add a higher rpm range and more oil demand. Even mike Phillips (Am&p/engine masters)does not hesitate on oil modifications. I would have to follow the master. I have seen noise that could be mistaken for valve train actually be out of round rods. Junked a whole set on an engine. Shop could not rebuild. I would tighten rod bolts to spec and measure as the early rods this is common. Might be your whole problem as you have not mentioned that you found the noise issue and addressed it. Either way I would check rods first . Before cutting crank or ordering parts. This may change everything. Or add to the list of parts needed.
I do use the lathe and mill, but I dont do things to tight tolerances as is never required for what I do, so a normal set of digital calipers and an outside Micrometer is all I have in terms of measurements tools. I'm guessing what I have to do is exactly what this guy is doing right? it does make sense doing it the way you guys are saying.... will take me longer as I'll have to wait for January for the bearings to get here.. but I might just do what you say. 1 - order 0.020 bearings to be on the safe size 2 - Once they are here fit them to the mains and rods 3 - measure crank journals 4 - measure bearings 5 - the difference between the 2 is what I'll tell the machine shop to grind got that right? In the mean time I can keep on cleaning and painting the block, heads, timing cover etc... So once parts are here will almost be everything ready to be put back together.
You'd be surprised how little metal needs to be removed for a scratched/ grooved journal to clean up. I used to work at a machine tool spindle rebuild facility and ground i.d. & o.d. housing bores/ shaft journals for new bearings. .0002 and under was main tolerance used.
I can't speak for every single Buick 350 ever made, only the ones I've dealt with personally, as well as conveying information I have gleaned from others' experiences with them. I've had '68 350's (as well as other newer ones I've dealt with), with 2 barrel and 4 barrel carbs, revved way, way past where other people say they are supposed to give out of breath and never ever had any issues with oil pressure or bearing failure. Others have said the same. That said, I also suggested here in this thread that any oiling mods done would add extra insurance against any potential failure, and so while the engine is already torn down in this state, is a good idea to help it out any way you can. Why not, right? Simple enough. The comments about over-engineering was intended to reinforce this general idea, as well as stating that everyone who seems to think the Buick 350 is a ticking time bomb unless you do umpteen modifications to all the 'weak' factory parts isn't entirely accurate unless you plan on revving it over 5500 on a regular basis and/or are going to produce some serious power levels. This simply means you have a great foundation to work with already, and anything you do over this will just extend the durability and life of the engine, particularly for high revving and greatly increased power levels. My comments are meant to encourage confidence, not instill doubt in this rugged engine. JP says the pick up tube was completely clogged, and ran it for 2 years before it started behaving badly. Hell look at the bearings and crank. No bearings spun, and yeah they look rough, but after having been through no oil for a couple of years? What does this tell you about the engine? You reckon a 5/8" oil passage would have saved it more than the 1/2" one? Aluminum (bearing material) is way softer than iron, much less nodular iron the crank is made of. Telling the guy he needs to grind his crank .020 is, well... shall I say, unnecessary. Smooth it over and be done with it. Raise your hands here fellas. How many Buick 350's have you torn down because of spun rod/main bearings due to insufficient oiling, that wasn't beat the **** out of due to super high power outputs on stock parts? This general myth that stock engines are junk and need to have their hands held all the way through a 'proper build' is bunk. It's not a 7000 RPM racing engine, though trying to twist one there using stock bearings and oiling along with a racing cam could be the real reason your lower end crapped out on you. ...but a stocker with a mild bumpstick and a 2 barrel? How is this even remotely close to being a 'higher RPM powerband' that would normally require oiling mods? You guys are blowing this way out of proportion for this particular application. Hog out the oil journals if it makes you feel better, but don't think for a minute it's somehow going to be required in order for the engine to live. It's one tough ass engine by its very nature, and came that way straight from the foundry. Buick didn't make junk, and the suggestions and mods we come up with 49 years later isn't somehow light years ahead of the geniuses who designed these works of art all those decades ago.
Generally a .010 regrind is used for high mileage normal wear to get back to factory bearing clearance. .020 is used where there is damage to the journal such as in a spun bearing, etc. You have one bearing shell which shows damage, the real question is just how much. I would measure that journal with your dial calipers and see what you get for wear. If it is more than say, .005" or shows visible scoring the safe thing is to go for the .020 bearings for that set (mains), the .010 for the other (rods). But again, measure the bearings, subtract .001" and order your journals ground to that size plus zero, minus .0005" Or if you are worried about your measurements subtract .0015" and use the same tolerance. I wouldn't go smaller than that, you'll lose oil pressure if you do. Jim
