Hello Cammer man,
You say that you found some dimensions on the net, I want you to think this through please.
You never know what you have until you actually measure it. I wouldn't trust the net for a dimension, you as the builder have to confirm it all. Just measure it all to be sure. We always have. Any one little thing can bite you. Every size and spec in an engine is your responsibilty. Your reputation is made from how well you do.
For ring lands, I say confirm it all. I have hardened and ground blocks, called go no go gauges. They are precision ground, I made then years ago, heat treated tool steel, surface ground.
You just check all of the lands, piston by piston, they should be fine but I have caught a bad one or two this way, on custom pistons. You can stack feeler gages but be careful not to score the lands. Make sure your feelers do not have a sharp edge which some have,dress it back.
I have caught inadequate back space too. Check that by setting the ring in face first, the part that rubs the cylinder wall, slide it in to the back of the ring land, then measure the clearance from the front of the ring lands, to the curved back of the ring. This gap is your back spacing. Do them all. Less can be more on a competition carb car. Give us this spec. Keep your specs on a build sheet too. This way, when you pull it down to service it some day, you can gage what wore by remeasuring the used parts.
Then measure all the rings, for width, they are usually all fine, but I check it, all of it, to the tenth. Most custom piston makers, have a ring room full of rings to sell with the slugs. I recall 2 times, having to trade back some scrapers that were about a thou less wide, just to match the remainder. I suspected that kits got mixed and this happens. So it takes less time than typing this, ha ha.
For you, this is a good learning exercise. Might as well practice with the mic's and the tenth vernier scale.?
You can feeler gage the width of the land too, by comparing a new ring to it. Slide the ring in backward again, then see how your 0015 gage fits, then 002. And depth mike the back spacing.
Also,but you need to decide if you want to gap the rings with a torque plate on or not. If I dont plate hone a block, which is rare, but this is sometimes done on a lot of blown stuff, with sleeves, then no plate is used to fit the rings. There is a case for stressing the bore to gap the rings anyway, but this is your call as the builder.
But if you are trying to win, in class racing, or in a team setting,you can do a long list of tricks, including doing the valve job or lapping the valves with a torque plate installed. Lapping rings, lots of little tricks. You are not really going to need that, but, when you fuss and fuss, you get some satisfaction too. When you leak down the engine later, and all of the numbers are the same, and small, you kind of smile. This can be the edge you need, the game of harnessing free horsepower, or building an engine that lives long enough to win, and that does not grenade.
Often a well built engine has more even static and dynamic compression too, and usually better cylinder balance, power wise, and more. Compression balancing can actually extend crankshaft/bearing life and more. Often the out drives, like all of the chains on a Cammer, see less stress
On TRW or FED Mo pistons, I have shimmed the back space out, you can get special shim stock 'expanders' which is spring tempered stainless. It can help some class builds, not needed for most new style pistons. Never hurt back then. Still do it in some settings. So look into the land depth and tell us what it is.
Your suggested end gaps are not ideal. Lets hear who's piston, what ring, and if you are setting them with or without a torque plate. You can call your piston vendor for a nice starting point. They suggest these dimensions a lot, due to the properties of their specific material, forgings and so on.
You are designing a lot of horses out of this engine, by reducing the compression and cam timing, so, a lot of the high speed, or blown gaps do not apply. The bore concentricity factors in, so tell us more please. I'd like to see how round and tapered your bores actually are, just measure it, take notes. Give us the specs please.
Some guys use a head plate, to distort the bore, but then relax it, and do the rings without re stressing the block. We always asked, if we fit the pistons with a head plate,why not the rings? Ideally, the bore should be measured and fit the same way to me, plate on, so doing the rings, plate on, always made sense to us.
Here,you have an alloy block, with sleeves, it is less of an issue but worth comparing. Depends upon how trick you want to be. Depends on the actual parts too. SOme blocks from the same vendor, and not as hard as others, same with heads. Some end up too soft, and some won't even maintain the torque for long.
On doing that job, gapping the rings, I have special tools that you can make. These make doing it all the same, and a lot easier. I have a big piece of stock that is turned and make a depth setting fixture. It pushes the ring down, the same, every time, with a torque plate on. We use a similar tool to set the sleeves
That reminds me, again, did you set the sleeves our did your machinist?
On gapping the rings, I also had some flat top pistons, which are made in steps, like 4.00, 04.03,4.05,4.133 and so on. The head or crown is turned flat in a lathe, just mount the soft jaw piston vise jaws(another tool a good engine shop has), and the skirt is turned mostly off too. These are for use if a torque plate is off. The depth works fine on the bare deck ring gapping operation. Usually blown/sleeved/billet block, or bone stock
It is de burred. It has three washers pressed into a land, at 120 degrees apart, to slide the rings, one by one, hole by hole, to the same depth in the bore. This is much easier than 'Eye balling' each one, and guessing if it is really square. If it is not square,the gap comes out wrong.
I have used a dial caliper, you cinch the stop screw so that is not moving ,,,LOL And use the depth part, to set the ring square to measure, in a pinch, building at a race.
This is slow and tedious. I would figure something out.
Do it right if you have time. The washers just act as down stops to let you work better. Start the ring , then push it home with the checker, slowly. Then measure the gap, pull it out, trim a thou, back in, square, check again. Over and over.
Then use masking tape or a layout table to number each ring pack, for the hole that it was gapped for.
Now for my concern,
On the main bearing clearances, you have some at 0020, and some at 0030 ? And you have decided to run that, and not see if the crank is running out?
Don't be offended please, we do a bone stock street gas build at least within a few tenths out here, so you do whatever you like. For me? I would do my best to make it nice.
Sure, after break in, you can lose a tenth or two off of some bearing inserts, but the big crank pin here, say the 0020 clearance guy, can settle in it's bearing, by point loading it to wear faster. The 003 journals will kind of let the tight guy even out,but in doing so, that bearing loses over plate, and some of the features designed in. On a street engine, a cold start is a big wear factor, so having the crank setting pretty even, helps it live.
Tell us your clearances 1,2,3=Thrust,need 2 specs please,4,5
Coated or non coated bearings I wondered too? Coatings have never been better. More free horsepower or durabilty sometimes, free meaining, psiton vs piston, etc. Power wise.
Can you list the main bore sizes as well? In the block, that size? On the X or vertical axis? And the eccentricity and so on?
Personally? I have never assembled a street or endurance engine with a full thou variation. On a fuel car, just going back for another pass, with 60 or 70W, no big deal.
But that extra 001, is a half a thou per side, and a half a thou, well on some components in an engine, that can be bad. Like on a wrist pin, to the rod or inside the piston to the pin.
Little side note, we want to check your pin fit too,pin to piston, and check the pin fit to the small end of the rod, and also the wrist pin end play to the lock rings, for later.
But remember, the mains feed the rods. Your oiling system, is a series of controlled leaks, daisy chained one after another. A pressure loss here, affects the pressure down the line sometimes. We were keen on maintaining the oil pressure and volume all of the way to the back main. We did a lot of testing to help engine live.
The rate and volume fed to the rods, is affected, by the leakage, at the mains. So a real loose goose main,will deny the adjacent rods some measure of oil. In turn, the side clearance of pair of rods, will splash a bit less too, while others may be biased to through more. That affects things like pin and cylinder wall lubrication, and the rate of which the underside of the piston is cooled. Splash helps pull away piston crown heat too. I like it all even and close.
If you list all of your dimension in columns, as suggested, the cause of this range will be on that page. The numbers reveal a lot. Is it the block, crank, a bearing? I wonder and want to improve this if possible.
Tolerances can also 'stack' on you. Parts range sometimes, so changing them around, can sometimes improve the fit. So can some adjustments.
I wonder, did they hone the main saddles funny. Sometimes if you rush a guy this happens.
If the main pin/journal is small,and the bearings shells there mic smallest, the block may have been honed wrong. This happens if guys are not good at doing billet caps.
If you do not dress the stones on the line hone well, and often, and/or trade sides at and even rate, some guys line hone a taper in a block. I do it from the front for 3 licks, then the back, 3 licks. That evens out the work. Measuring all the way helps
If I get a line honed block, I dial bore gage it, and confirm that it was done correctly. I hope you did this too. All machine work is not automatically 'right on' at all, no sir.
This is why I want your numbers. I have seen guys hand me a block, honed, and the saddles taper 001 front to back, or back to front. Thats because the honing stones were not trued well. On an aluminum block, the block is soft compared to the billet caps, so this can mess the machinist up if he does a lot of stockers only. It can taper the stones fast too.
I suspect that the block may be tapered. If so, the machinist owes you a do over
Also
On setting the rear seal, and gluing it in, do you plan to let the filings from doing the rings just fall into the bores, maybe down to the crank, or will you just run it.? I wanted to figure that timing out too. I want your sequence to come together well
Personally, you can't do that in a race engine shop that I know of. The filing happens in the mock up area or machine area,you clean, then assemble. So one room is fine, just keep the grindings out of the finished engine. Gapping rings creates shavings, you can clean each ring, over and over, in and out, but this is too slow and un needed really.
Just another little fyi tip in case it helps ya pal.
You can do anything for your own stuff, but I wasn't trained that way, so I think my point is about sequencing, and doing high quality work. I file fit the rings way before I final install a crank. Set the side clearances on the rod pairs, confirm the piston to wall, and the rest of the little things I suggested.
Remember, the mock up goes through these steps, and sometimes the pistons, after checking the valve to piston, come out to get milled for more clearance. So until I know how the piston to valve is, I get this correct, then balance it even. If you have to add valve reliefs, you lighten the pistons some more. So the crank needs a bit less bob weight. Some guys get in a rush there, and have to pay to re balance !
Your shortened ramp cam, and current pistons should be OK, but remember this for the next time. And check it. Get 16 low tension checking springs installed on your heads too. And figure out a plate or bracket to mount you dial indicator base on to check all of the valves.
Also...
I sometimes relieve the bores in a small bore cammer like yours too, did you check that and look into it? We often shaped the edges of the bores or allow the valve to flow a bit less disruptively. That requires grinding, pin rolls, carborundum dust, again, you do a full clean, after. For the street, you don't need that handlful of ponies maybe.
On the rings again, also, did you have a stone to dress the edges? I used a diamond file, it is square, and an Ozark stone. That is a fine grained, semi soft dressing stone.
Each end of the ring must be carefully chamfered.
Do you have a ring gapping tool, machine, or just free handing them with a file? If you are a very skilled metal shaper, the file can be OK, but I had the trick machine with the electric motor, now I just use the hand cranker which is fine, and stone them 2 ways. You do not want a sharp edge there, cutting the ring lands, the rings rotate and you do not want the ring acting like a cutting tool
One tip, go slow. It is easy to over cut a ring and you can't do much but get another for the set.
On a Moly ring, I do not file or de burr in a back forth motion, I go in one direction, to avoid any isses similar to the old Ramco Double Moly days. Just a habit based in TLC kind of. You ring set and seal is a crucial aspect of your engine.
OK, have fun
Be careful doing the rings, they can cut your fingers. As you gap them, the edge gets sharpened some times, and it can get ya. Seen guys cut and cut their hands if not careful. A Latex glove can help.
If you are trying to be trick, well this is not a race engine I see, pump gas,that's cool. I have another special tool, to assemble the oil rings, in each piston, slide them in, using a tapered piston installation cone, the old Ed Pink kind. Upside down. The piston for each hole, and only the oil ring, go in the bore upside down, to the bottom. Then you pull the piston up the bore, by the pin, with a tension reading pull scale. You read the scale and note the drag.
That way, you can adjust the expanders to the drag you need, and make them all the same. You just need the side of a bench grinder usually, fine wheel, dress the expander slightly,and then deburr, re test.
If the clearances are all equal, and the oil rings all draging away on the oil film in the bore equal, and the rod side clearances are also equal, along with the oil volume, enhanced with equal clearance,we figured, for a race engine, the oil film per hole, might be more equal, so any scuffing might be more uniform, along with wear.
If you are just in a hurry to build a street engine, some of these blueprint tricks are for learning the trade, or acquiring a higher level of precision. It is also part of why a Pro has to charge you what they charge. Blueprinting a carb engine, takes a lot of time and special tools.
Nice work, just giving you glimpse into how we did it for Ford back when, and since.
Hang in there.
You can just 'bolt it together', some do,or blueprint it, and that comes in levels. We did/do tenth tolerance engines. That is an advantage for some settings. I think all of these expensive parts deserve no less to be frank, but if you get close,given the target use,cool beans maybe. This is your call. I just don't want to see you miss something that can 'hurt it.'
But a lot of guys get it close, and send it. This is your build sheet. .we can make suggestions and give tips, but you own the result as the builder. The result and outcome can be very nerve racking at times.
I like precise assembly, that is how we did it at Ford Racing, very very fussy.
But for the street, some guys just get it close for sure.
I have to be honest, I do not like 0020 and 0030. For us, that has to get corrected. Crank may be tweaked. And I never lay a crank until I know how straight it is. I explaned how to check it with an indicator.
If you want to get a better idea, just do the steps I shared. Then let us know. I still wonder why you found taper and eccentricity there too.
Good luck and have fun pal. If you lived close by I could be more help. Typing an engine together is , well, a challenge for me...I think I gave you a jump start.
Patience and precision is good, to us.
I am really busy, working long days and weekends. Please email me if I can help further.
You have a fun car in the works and I am proud of you for trying to learn how to build an FE.
Thanks
