Cop Car

iTrader: (14)

whats the stock main bearing and rod bearing areas of the crank? i have my motor appart and i want to see how much wear has gone on with the crank..

you guys think it would be fine to replace the crank, rod and cam bearings and get new piston rings and not machine the block or crank and reuse stock pistons? dont say "you might as well do ___ while its appart" im asking if it would be fine to do this on a crankshaft that is barely worn.

aux_fast_cam

I would at least bore the block and get new pistons and rings. the rods and crank could probably be reused with new bearings. block bore 3.905 with 3.903 pistons and have whoever bores block do new cam bearings and put pistons on old rods

I think this is the minimum that can be done if all else is in good shape.

kossuth

iTrader: (12)

Ok grab a drink and sit a spell I'm gonna get alittle long winded here. Have a machine shop check the crank unless you already have some really good tools. Too be honest unless you have a really good set of calipers you aren't gonna be able to accurately check the crank or anything else on the motor to be honest. A .001 accurate caliper is not gonna do the job. You need something that is accurate to .0001 which is gonna cost you more than what having it checked at a machine shop and polished. It cost me about $50 to polish my crank. Polishing it isn't a bad idea because like honing the bores does to the rings, it gives the new bearings a new surface to seat on. You also need to hone the bores. You DO NOT NEED TO BORE IT!!! As long as the cylinders aren't messed up IE gouges or scratches hone it. If you are looking to do this cheap then believe me on this one. It's gonna cost about $150 to bore a block and about $500 for a set of 3.905 pistons, Honing the block should cost around $100 or so. While the shop has the block to hone it also give them the pistons. They don't need them for anything other than to just check the final size of the bores AFTER they hone the bore. Honing it is gonna remove .001 or so out of the bore and you want to ensure you are still in spec. Remember you are working with an aluminum block, and clearances are an absolute on these motors. Ever hear a LS1 with a slapping problem??? Not something you want I assure you even though it would make alittle more power.

I've done the whole bit you are doing now and will offer this advice. If you go with Federal Mogul bearings or Clevittes and the crank is still standard grind but is on the low side of what is acceptable get .001 + main and rod bearings if you are putting it back together mostly stock. Those two companies don't like to machine bearings as close as GM does and that is why you hear about all these oil pressure problems that people have on rebuilt motors. My crank is on the low side of what's tolerable and I went with a set of .001 bearings and my mains are sitting at .0017 or so all the way. If your crank is on the high side (very unlikely for a used piece) then you would be fine with standard size. If you find the crank has to be turned then have them turn it to the high mark of what .010 would be and go with straight .010 under bearings. The Federal Mogul bearings you can get .001, .002, .010, .010 + 001, and .010 + 002 plus or minus bearings. If you pistons are on the low side of what is acceptable you have two options that I would suggest. First if you are on the cheap is have the pistons sent out and have the skirts coated like the newer LS pistons are. This will cost you about $20 a piston or $160 total. Or if it is the piston that's alittle smaller which isn't likely but still you can get a set of sealed power pistons that are standard or 3.908 in size that are hypereutectic for about $250 or so for the set with rings and all.

In the end it's your decision but like I said polishing the crank and honing the block would definately be on my list of things to have the machine shop do. They have the proper tools to check things with and such. Also ask to be shown the specs on things like the crank and the bore on the block. Most shops will let you and plus that way you have piece of mind that you saw it all yourself. Below are the specs on the crank and cylinder walls and cam bearings for you.

Crankshaft rod bearing journal diameter = 2.0991 - 2.0999 in
Crankshaft rod bearing journal out of round = 0.002 in (basically how much the journal can oval out)
Crankshaft rod bearing journal taper = 0.0002 in (thats the max on 1/2 the journal length)
Crankshaft main bearing journal diameter = 2.558 - 2.559 in
Crankshaft main bearing journal out of round = 0.000118 in
Crankshaft main bearing journal taper = 0.00039 in
Crankshaft end play = 0.0015 - 0.0078 in (basically this is where you see how much the crank walks in the block)

Bore information will follow in next reply

kossuth

iTrader: (12)

Piston diameter = 3.8962 - 3.8969 mm
Piston out of round limit = 0.0007 inch
Piston to wall clearance = 0.0007 - 0.00212 in (this is where I was talking about the whole if the pistons have like .002 of clearance in the walls I would have them coated)

If you think about all the information I have just provided you now you can see why you want somebody to check things while they are down. Motor has a number of miles on it, It costs very little to have things checked vs having something go south later. Also remember you CAN'T USE ARP MAIN STUDS unless you line bore the block and that is gonna probiably cost $200 or so. Have them check the line bore and if it's good just get stock bolts ($70 for the set) and be done with it. If it needs line bored then you will have to address that at the same time. I know you are thinking, "Well it ran just fine before I pulled it down and the bearings and such all looked good". That's fine and dandy but what if the block is slightly distorted now and the line bore is on it's way out? Then you know what the result will be. The key to a good running engine is keeping all the running clearances within spec. That's what separates the good rebuilds from the bad. You should probiably spend 1/2 of your money at the machine shop. As I see it now you have $140 in rod and main bolts $100 in head gaskets and bolts. $170 in main, cam, and rod bearings. $150 in piston rings. You can see where I'm headed with this obviously. Any questions post up and good luck with whatever you decide.

92zcamaroperson

iTrader: (18)

Arent the ARP main bolt just stronger than stock ones? Or do you mean main studs? Can you reuse stock main bolts?

I have a shortblock that I just bought with a spun crank bearing. Would it be best for me to just haul it in and let a machine shop handle the dissassembly and reassembly or is it safe enough for me to do. When installing the crank and new bearings do I have to clearence several things or anything?

kossuth

iTrader: (12)

Yeah, you caught me LOL I meant studs I'll go up and edit that. Ok it spun a main. You can disassemble it no problem, plus it will save you a ton o money. If you haven't torn into a motor before it isn't rocket science. Plus I know I'm more of a visual and hands on type of learner so it will give you a sense of what you are getting into. Tearing it down you don't have to be super careful except for the pistons when you push them and the rods out through the top of the bore so you don't ding up the cylinder wall, but putting back together you got to be for sure.

It will have to be line bored and probiably will have to have a bearing with a larger outside diameter installed to salvage the block. I looked on federal mogul's and clevite's websites and I saw no listing for a bearing like that BUT I know it can be had, your machine shop may have to special order it though. As a kid I grew up on a farm and we had a 1066 Farmall tractor we used ALOT. Tractor spun a main bearing. Getting a good used block was gonna cost about 2k . What I remember most was splitting that heavy SOB tractor LOL(8500 lbs) in 1/2 to get the motor out. It cost about $800 in parts 10+ years ago to get her back running again (had to oversize the mains like I mentioned) but it's still working away no problems since.

Your main bolts can't be reused. I reused my old bolts and torqued to 55 ft lbs on the inner bolts and 50 on the outer bolts just to plastigauge my mains, but then I replaced them with new bolts once I was certain it was all good. So I wouldn't throw them away but get replacements you will need them. It's about a $70 difference for ARP hardware vs stock stuff. Being it is gonna be line bored anyways that's your call.

Disassembling a LS1 isn't hard at all, just keep stuff in zip lock bags, keep it oily, and keep it all labelled. The parts I would give the shop being your motor had bearing problems is pistons with rods, camshaft (if you have one out of that motor you want to use) crank, and block. Rest of it unless you are gonna have the heads gone over has no real need to go to the shop. Crank unless you are getting another crank will abviously need to be turned .010 under. As for the pistons and rods "sigh" have the big ends of every single rod checked.

This motor had bearing damage and the journals have been heated in a manner which they were not designed. It is entirely possible the rods are fine but while you have it down have them checked. If they are out just get new rods, they are $90 each new and most shops charge close to that to resize them and if you do resize a rod then you are in the boat of having a mismatch of bearings ect ect. If you resize one rod you should do them all. Keep as much of the rotating assembly the same. It will make parts ordering easier and cheaper.

A bearing for a resized rod is gonna be a special order part. If 5 or more rods need resized at that point I'd evaluate exactly what you want with the motor. Putting in forged rods is not much more money at that point in the game, but then you have to replace your pistons or go with a Manley rod on your factory pistons, but why at that point? Would probiably make more sense at that point to find a used rotating assembly on Ebay or something and pickup an entire rotating assembly if you didn't want to get a ton o money into it.

Your machine shop will know, but I'm gonna just say this, you can not put aluminum parts into a normal parts washer. The chemicals in a normal parts washer will pit and eat aluminum. Brakeclean is your best friend. Methanol works great too if you can get your hands on it.

Hopefully this gives you an idea of what you are gonna get into. This isn't everything but it is a good starting point.

soldeir

iTrader: (10)

hey kossuth you said everything veary well i couldt have said it better maybe cop car will take your advice and build the motor the right cop car take kossuth advice and build a motor the right way dont go cheap and put 200 miles on your new motor then spin a bearing

92zcamaroperson

iTrader: (18)

would you say its worth having the block "hottanked" or "dipped". Any idea of a decent price for that?

And what does it mean to have the block line bored?

kossuth

iTrader: (12)

They will clean the block up after they machine it I wouldn't get too crazy with that yet. That is something you will want done after all the machining is done. As for line bore.

If you have ever had a motor apart the main caps are what holds the bearings up against the crank and holds them in place. There is a similarly machined area in the bulkhead of the block that does the same. What a line bore does is there is a long cutter that is just as long if not longer than the block. What they do is the torque down the main caps with no bearings or crank in it and basically machine the bores where the bearings would sit. The bearings are a precision fit, that is why the mains in that motor you have spun. The block distorted somehow or the bearings where subjected to a low or no oil pressure situation. So to correct the situation you must oversize the caps and bulkheads in the block to correct a spun bearing condition then you have to go with like I said above a larger OD bearing. Because of the damage from spinning it you can't just go with a set of stock bearings material has been removed and the bearings will not properly seat in the main cap or block bulkhead. The main bearing journals also must all be in line in the crank for it all to spin properly the mains must be in line for the crank to ride in the block properly. Think of it at taking a piece of steel rod that is perfectly straight. Support it on each end and in the center and see how true it spins. Ok, now take the center support and pull it down some and see how hard the rod spins now. Crankshaft will do the same thing and it will cause bearing failure if the main bearing seating surfaces are not in line. Here is a picture I found on the web that would be of help to you to understand if I'm not being clear. As we all know a picture is worth 1000 words. No it's not a LS1 (actually it is a V12 rolls royce but you get the idea)