Hi.. so I've measured the piston at the top, just above the first ring, measured 3.765 couldn't find any markings on the pistons...so assume they are standard and not over bored? can't see any 3.765 on that table though..?
A caliper across the bore is good enough to determine if a bore is STD, +.030", .040" or whatever. Service manuals instruct where to measure the piston. It's usually at the skirt, often just below the wrist pin. That would tell you the clearance between the piston and bore. That's one reason I mentioned Googling the info. It wasn't to be a smart mouth. I assume people would research their basic info needs and ask forums for info not as commonly found, or to help with decisions based on what the books leave out.
Sorry, I didn't read till I got back from the workshop.... dammit! I'll go there again tomorrow evening and pull a piston out and measure it below the pin.... I didn't want to measure across the bore because there's a bit of carbon built at the lip and didn't want that to interfere with the measurement... I don't have a service manual
Measure the bores anyways. If the caliper cutting through bothers you, then wipe or lightly scrape it off. You'll need to determine if there's enough of a ridge to avoid more machine work and measure things still. What if the previous builder messed up on the piston clearance? No need for the service manual. That's why I mentioned Google, so you don't have to ask a question that someone else has to Google and copy the info for you and waste your trip and time...along with whoever helps you because you ignore advice.
Right, just got back from workshop... measured the piston and it's 3.795, so I'm guessing that's standard size right? therefore the reason also why there's no markings on it. the bore cleaned up pretty well, so there's no lip. I measure it but I can't remember exactly but do remember was almost the same as piston. sorry, I was in a rush and someone in the workshop next door started chatting to me and he does not shut up, all I wanted was to get out of there hahaha Oh and by the way, got news from the engineering place where the crank went to. afterall what they done (and said was enough to clean up) was 10thou on the big ends and a polish on the mains. Parts list looks like this... think I got everything? CCA-504-16------- Summit Valve seals 14.97 FEL-MS96006----Summit Valley Pan 20.97 TA1436------------TA Valve springs for 212 cam 75 old ones-----------TA Spring retainers 0 TA_1521----------TA Timing gear stock replacement 39.95 TA1635C----------TA piston rings standard 75 TA212-350-------TA 212-350 cam 185 TA1406-----------TA Hydraulic lifters 68-69 79 TA1419A----------TA Stock pushrods ?? CONFIRM 49 TA1507-----------TA oil pump rebuild kit 29.95 TA1502-----------TA oil pressure regulator 19.95 TA1510-----------TA booster plate 25.95 TA1704----------TA oil pump shim kit 20.59 TA1550----------TA standard Main bearings 89.95 TA1540----------TA .010 Rod Bearings 65 TA1559----------TA High Perf cam bearing kit 74.75 TA1705----------TA full gasket set with neoprene 59.95 TA1520D--------TA 5/8 oil pickup tube 29 TA1515----------TA Rear Main seal 16.95 Total - 934.99 Ouch!!!!!
So they ground .010" on the rods and only polished the mains? I'm going to call that into question right away. Grinding the rods moves the crank around some. The mains are therefore done afterwards out of near necessity. Saying .010" is pretty meaningless being that there's a range it could end up at. Is it at the high side, low side or nominal? What are the exact measurements in tenths? See what I mean? (not busting your balls, just saying) I'd figure out IF your pistons have correct clearance before deciding they are going back in that engine and ordering parts. Their condition needs to be assessed yet. 'If'...it's already at .005" clearance then you might have an issue. I was hoping you'd look up where Buick wants you to measure those at. My reply was general and intended to get you looking.
From what I understand, they didn't ground 0.010. the crank is 0.010 smaller than original out of factory. I dont understand how grinding something moves it around if then you compensate with oversized bearings.... the actual centre should be pretty much in the same place it was. take from one part, add on the other. ok there might be a slight variation, I'll just live with it. What do you mean by pistons having the correct clearance? If the bore is standard, the piston is standard, get new piston rings, make sure the rings gap is as it should be and off we go? Not sure about this piston clearance you are talking? Even on the bikes I do that, if standard, do a hone, off we go.. or rebore, get oversized pistons, slap some new rings on it and off it goes... the pistons are fine, not scored or anything. From that measurement I took, looks like the piston is standard right? Sorry.. I'm not trying to be a smart ass, but I think the level of detail is way too much for me... I dont' want to be perfect as I don't have the love for this engine to do it that way. I just want to get it going, cheap as possible. if it doesnt work.. It will go up in flames.
http://blog.wiseco.com/piston-to-wall-clearance-myths-mysteries-and-misconceptions-explained You almost certainly have some taper in the cylinders, so clearance will vary. Cylinder taper is one reason an engine rebuild includes over boring and fitting new pistons.
ah!! thanks for that Larry. well, the way I see it is I wasn't even going to touch the pistons, so a hone and new rings is a luxury. hahaha A rebore and new pistons would 100% mean the engine would go in a scrap pile as I would not be spending that kind of money on it.
I'm sorry we are helping you save money and that you don't take advice from professionals. You are dealing with a botched job and were handed the problems caused by ignorance. It would be incredibly foolish NOT to double check whatever else they may have messed up BEFORE deciding to spend a dime. If you are showing that you are both willing to put $1000 into this and at the same time UNWILLING to make sure it would even live prior to assembly, then you would be showing the same ignorance that began this project. Right now you want to hurry to meet your shipping deadline and are taking intentional steps that have a strong chance resulting in mishap, but disguised as "I'm not looking for perfection" or whatever. I can tell you that bad things happen trying to force your will on a machine. I regret assisting this thread.
what botched job? seems like the engine was pretty much standard except for a new timing gear, 1 lifter and 1 pushrod. Believe me, I take all the advice and have learnt a lot with all you people have written here, but some stuff I just can't do. This started as to me not spending money.. I just wanted to sort the basic and get back on the road. Going to the extent I have now, of grinding cam, etc is already a big thing... if I had, at the start found straight away that the valve racket was due to the oil pump, I would have just replaced that and leave the rest as is. So, to me, doing what I'm doing is already a luxury. I take the advice, but in the end it's up to me to make the decision of where I want to go. The shipping deadline is very very important. if I dont meet that, then I only have the parts in June or July. $900 dollars worth of parts, using standard shipping methods, would probably end up cost me around $2k or more once landed here. I thank you for your input and i'm sorry you regret assisting.
Seems to me the engine was a victim of an inept and careless assembly before you. I wouldn't assume they did a single thing correctly, looking at what's there so far. You have enough measuring tools and skill to at least check things over before deciding what it really needs spent on it, and then make a decision to actually use it. I would assume it to be junk until you prove it can go together as you intend. (any engine with problems) If you do the same as the last person and force your way upon it, it will again respond in kind. I can tell you that prioritizing deadlines over the actual engine itself will end up costing you the engine. I deal with shops all the time that have the mentality that "If it ran before, it must be fine". Their stuff blows up and they just blame it on the garage assembler customer. I don't care about your engine, or if you blow it up It's just a machine. If the previous person is blameless for the result, then assume it is too worn to proceed until proven usable. It seems like you are going to possibly make the same mistakes. Believe it or not, I've driven an engine that had .013" piston clearance with a cast piston and you only could hear a slight rattle for a moment on start up. Crazy It would have been recommended to be .0035-.0045" max. For what it was it had plenty of snort. Made pickup truck go sideways at will. Roughly 10k miles later it shattered a piston, the rest were discovered cracked at tear down. Sad thing is that someone put a good chunk of change into it with name brand parts. Complete victim of ignorant assembler. My gain as it was sooo cheap to get. The block crank and rods went on to a 600hp project. I get it, your priority, your decision. I try to deal with people that don't project so much apathy. Good luck. Peace.
Nah... i don't think it has been touched to this degree i'm going, when taking it apart it all seemed pretty much standard from factory. all the wrong things I believe it to be due to a snapped timing chain, and oil starvation...debris going around etc. I don't have the measuring tools required for this size of pistons, other than a digital caliper. my micrometers are way too small and dont have a boring gauge either. I have the day off work, I will go down the workshop and measure it the best I can... might ask one of the worshops next door if they have something I can borrow. I've just watched a video on how and where to measure to check the clearance, so I'll do that. But just to clear, the measurement I took means it's a standard size piston right? I'm guessing if standard then its a cast one correct?
How difficult is it to redo the Harley motor. Price of rebuild kit that includes new pistons? Just a thought/ should you be able to revive Buick. You would become. The Buick expert in your town. Assuming people allready know you as accomplished bike mechanic
The harley motor is dead easy and simple. Pistons are £100, rings are like £20....it's very cheap because it's popular so parts are easy to come by. dont spend much money at all and can do all of it with the engine on the bike. I have had an engine done professionally and the cost of the whole build, including spliting the cases and check flywheels, pinion, new pistons, rings, valve seals, etc.. was only £750 I'm no mechanic...I do it as a hobby on my own bikes. Buick engines are not very popular here and parts are just non existent. Chevy and Ford is a completely different story though
OK... adjust my comment to say, "careless and inept repair" because it clearly didn't make it very far afterwards and I'd be worried about what the last person either inflicted to it or overlooked because they couldn't be bothered. Point still remains that it is likely a very worn factory (almost untouched) engine because it had to have repairs. I like how you state that you aren't either a mechanic or a machinist but are willing to argue with several. I admire the tenacity. I'd hoped your level of stubbornness were more focused on finding a way to use what you have in hand to simply look your engine over rather than dispute what professionals are telling you, or disbelieve aspects of machining or repair. I'm glad you found a video that opened your mind and allowing you to see what we've already stated. It's kind of disrespectful to tell people that "(you) can't do that" or "this sounds too complicated". We can see what you have for tools. The piston and a feeler gauge would work in a pinch. To be clear, you've got enough info to ensure your list arrives with the right stuff and to answer your other questions.
errmm I didn't argue with anyone. Never have I tried to say or said that the info I got here was wrong...I don't have a clue. if anything I said the way you guys explain things makes sense in terms of mechanics and science... like the mesuring the bearings and grinding after to get the correct clearances for oil etc.. The one with the piston..well, if I measure and it comes that there's too much slop on it, then it's a case of it is what it is, as I would not be spending the money getting a rebore done and new pistons on it. If it does 5k miles and explodes I'll be happy with that as the cost wasn't great. I have to balance how much i'm willing to put on this engine vs what driving I'll get out of it. It's a buick engine.. its worth nothing over here, so there's no point spending money to make it last 20k miles.. or 10k miles for that matter. I appreciate all the information, never disputed anything, I have followed advice as far as the money i'm willing to spend allows.
If I've misjudged anything, my apologies. If the pistons are too sloppy, they could possibly be knurled to make them a bit bigger for a pittance in price. For a very low budget build like this, I'd consider skipping the crank grind for a polish. Ignore light scratches, it should run for much more than 5000 miles. (ignore my memory if they aren't light) Don't rope yourself into an outcome not knowing all the options or what you are working with. Around here, people tend to give away used pistons to replace collapsed ones for projects like yours. I didn't forget you have a container headed your way.
It'll run ok, just make sure the valves seal. You're not gunna beat on it too hard anyway. Drive it like grandma would.
