Ok so i finally got the pistons to go in and when i was torqueing the rod caps the first one went fine crank could turn pretty easily then i torqued the second.... wouldnt turn. I assumed i had 3/8 rods cause a 9/16 fit the nut so i torqued to 45 ft pounds. Well i thought maybe it was the 11/32 so i torqued to 35 that went fine until i got to the 4th one.... now the crank wont turn at all and i just dont get it (i got to rod and crank bearings)

Any advice or pictures/videos are appreciated

 

assuming correct bearing inserts installed and rod caps didn't get mixed,should be able to wiggle the rods on the crank journals ever so slightly...If you are not used to engine rebuilds,i can say they can be quite stiff to turn if the cylinders have been resurfaced and rings are new

 

The thing is i cant wiggle any of them. Atleast i cant notice it or not and i know its stiff but now ot wont budge at all. I think the bearing on the 4th one isnt sitting right im gonna mess with it tomorrow but i would think an 88 350 would be the 3/8 and need 45 ft lbs man this hurts my head haha

 

Rods may be backwards...

Rod bearings are not symmetrical. They are wider toward the edge that goes next to the other rod on the same journal, and narrower toward the outside. If they are backwards, the wide side ends up being forced to ride on the radius ground onto the journal.

Check to make sure the bearing tangs face away from the cam.

 

It shouldn't be very difficult with 2 piston installed. Off the top of my head I want to say that any SBC/LT1/LS1 short block I've assembled has always taken 16 to 17 ft lbs of torque to rotate.


Did you mark which cylinder (and direction) each piston/rod goes in when removing them?

 

I didnt mark it but the pistons have those marks which face the front i didnt think you had to put them in the same spot with new rings and bearings.

 

I like that you are wanting to dive right in on this project and I don't want to be that guy but put the tools and internet down for a bit. Do some more research and reading on how to properly do a basic rebuild.

 

You are "that guy" youre the same guy that asked if i was using a piston ring compressor.... and yes i did basic research everything i read said pistons didnt have to go in the same spot if youre getting new rings

 

You live and learn. We all start somewhere. I am no professional by any means but I have never had a motor I've assembled destruct due to neglegence. Just like you, I am self taught but I do/did learn a tremendous amount from certain people (a good person to listen to or ask questions to is SofaKingdom).

I've always marked everything I remove. Even with an indication of which way the rods face, I generally draw arrows pointing towards the harmonic balancer to make sure it is 100% without a doubt in the correct position. I even mark my main caps for both position and which way they face.

I was taught to always mark which piston/rod was designated to which cylinder. I believe the biggest reason for this is due to engine balancing but that is just my speculation. Each rod borw should be the same diameter regardless. Any shop I've ever been in does this too. Even when the big rig shops do in frame overhauls, they mark each rod/piston.


Have you measured any clearances? Even if you just use plastigage and its not super hot or cold outside, it will give you a general idea and might potentially show you were your problem is.
Make sure the bearing tangs are completely seated into the rod journal. As previously stated, each pair of installed rod caps should be able to slide forward and back freely.

 

I guess i need to go get some plastigage things and check the clearences im hoping thats the issue the bearings all look right but i guess that tiny bit would cause some serious issues. Im kinda learning as i go (as im sure you can tell) how do i know what the clearence is suppose to be?

 

Ok PLEASE correct me if im wrong standard clearence is what .002? I just checked with a feeler gauge (will that work???) and i have nowhere near that so i think i somehow have the wrong rod bearings.

 

Yes .002" is a reasonable rid bearing clearance. A bit on the wide side IMO for a street rebuild, but still entirely reasonable.

Can't check it w feeler gauges.

Yes of course it's always possible you have the wrong bearings. Mic your crank and see what its dia is. OTOH if it turned OK w ONE rod installed, then at least THAT ONE is the right size (or at least, not wrong in such a way as to seize the crank), which if EACH ONE can be put on a journal by itself and not lock it up, then that's not your problem.

Rods are probably backwards. Check to make sure the bearing tangs are facing away from the cam.

You should be able to grab the crank snout with one hand, spin it as hard as you can, and it should coast the better part of a full turn more. If the main brg clearance is right, the crank should get easier to turn as you torque the bolts from say 25 - 30 or so, up to their full torque.

I prefer to always stay to the lower side of the torque specs. I'll torque em to that, then whap em with a hammer real good, then torque em again. They'll ALMOST ALWAYS lose a good 5 - 10 ft-lbs from the whack: the acoustic effect, the vibration, settles the parts against each other better. Try it sometime, you'll be amazed. One of the best tricks I ever learned for getting consistent fastener torque.

Stock rod nuts should be around 35 ft-lbs. Much more than that and you'll distort the rod.

Should take around 15 - 30 ft-lbs to turn a whole motor, depending on rings that were used etc. Torque required to turn just the bearings, all of them together, is negligible; should be in the inch-pounds. Ring friction is what takes the torque to overcome. Also it will depend on the assy lube you use: I prefer 2-stroke oil on rings and thin stuff (5W-20 or 5W-30 synth, or ATF) on brgs.

 

I dont understand how they would be backwards i never took them off the piston and theyre facing the frobt like theyre suppose to

 

Your gonna hate to hear me say this , and I promise you I'm not taunting nor scolding here in the least , but , I believe your not marking the pistons as to which cylinder they came from is costing you dearly here .

Due to the extremely varied wear patterns between cylinders and their pistons in any given engine , even though those pistons (and cylinders) all started out life as being fairly matched , size wise , to within a few thousandths of an inch , a (engine's) lifetime of them wearing in at different rates means you've now likely got some "bigger" and some "smaller" pistons , by who knows maybe a wee thousandth of an inch or so . If all the pistons , worn to their cylinders , don't find their way back to where they were , you will have some looser and some tighter fits in your piston to cylinder clearance . And this very well would cause an engine that was too tight to turn , especially if it was more than one "too big" piston that found it's way into a "too small" cylinder .

I believe you now need to take it all apart again , and start from square one of measuring pistons and cylinders to see if you can figure out which "slug goes in which Jug" by comparing the measurements against each other .

 

Wouldnt that cause the piston not to fit in the cylinder?? And i had my block honed at the machine shop

 

If you hadn't had it honed , maybe , maybe not . But having had it honed , the wrong pistons going into the wrong holes is actually more likely , just that they would have been a really tight fit and hard to get in VS others that may have pretty much "slipped right in" being the too loose ones . I read your other thread when you were having difficulty getting the pistons to go back in , and the wrong piston in the wrong hole would have been a very likely reason why you were having such difficulty .

I know how bad it sucks to pull it all apart again , but ya gotta figure that it's being too tight is a matter of improper clearances somewhere , either the bearings or pistons . At this stage of the game , your still right there , it's all still easily accessable . What happens when you get it all together and it's so tight the starter won't even turn it ? Or worse yet , it DOES start up , and promptly trashes itself due to the wrong clearances causing a too tight piston to become literally welded into it's cylinder ?

Pull it all back apart , measure everything properly , and then resume your build paying mind of the required clearances . It's the only way to assure you'll have success here , and I can just about assure your engine's failure here if you don't .

 

It would be easy for them to be backwards, if you exchanged for example, the #1 & #2 piston/rod assys. If you did that, the side of the rod that's supposed to be up against the crank would be against its neighbor rod, and vice-versa. In which case, the bearing tangs would also be facing toward the cam, instead of away from it.

Not sure how many times I have to say this before it sinks in:

Rods are probably backwards. Check to make sure the bearing tangs are facing away from the cam.

 

Yep , I agree 100% . The chances of him getting all 8 correct without marking them are about the same as my being reincarnated as Elvis in a parallel universe somewhere . That's why I think he owes it to the build to do his best to try to get each exact piston back to it's proper cylinder by measuring them . Having the tangs wrong will lock it up tight when they are torqued , no doubt about it . But even if the tangs were by some miracle in their correct orientation the differences in the pistons themselves being in the wrong holes may be why he had to pound them back in , in the first place , before he had bolted up even his first rod .

 

I didnt have to poubd them in i got the narrow rings like i needed and they went right in no problem. Can i see a picture cause i have no idea what you mean by facing the cam....

 

I don't have any pictures of what Sofa is talking about , but when you see it , it will be plain as day . Hopefully maybe Sofa or someone else has photos of the right way the rods fit to the crankshaft with the chamfers facing correctly .

 

Like this:

 

Unfortunately I don't have any pictures. I can't think of any way to express it more plainly.

Facing the cam:

The cam is ABOVE the crank; the oil pan is BELOW it. When you put the rods in, you can turn them only 1 of those 2 ways: either the side (place where a bolt is) with the bearing tangs is adjacent to the cam, or it's adjacent to the oil pan.

As you rotate the motor, the rods don't change their orientation very much. The side that is inward, facing the cam, stays facing the cam; and the side that is outward, facing the oil pan, stays facing the oil pan.

The tangs MUST face toward the oil pan. Away from the cam.

Back in the day, rods actually had a little groove machined into the cap on the side OPPOSITE the tangs, i.e. TOWARD the cam. The idea was, as that little "spit" hole passed over the oil feed hole in the crank that lubes the journal, a little "psssst" of oil would get shot up at the cam. AFAIK that was only in the small-journal (265, 283, & 327 from before 68) but it's a good thing to remember about.

Vader's photos show REAL CLEARLY what goes wrong when they're backwards. The side he labeled "inboard" is the side that goes adjacent to the neighbor rod on the journal, and the "outboard" side, where you can clearly see how the bearing doesn't come near as close to the edge, is the side that goes next to the crank. The bearing is narrower on that side so that it doesn't ride on the radius on the crank journal.

When you put em in backwards, the wide side of the bearing ends up on the radius, which forces it about .020 - .030" away from the side of the rod touching the crank; and as long as there's only one rod on the journal, it works fine. BUT... when you put THE OTHER rod on that journal, and IT ALSO tries to force the bearing off of ITS radius, the 2 rods are forced together HARD, and the motor binds up. Usually it takes like HUNDREDS of ft-lbs of torque to turn it when it's like that, and of course, turning it in that state DESTROYS stuff.

Your rods are probably backwards. Check to make sure the bearing tangs are facing away from the cam... toward the oil pan.

 

As an old pro once advised, you should always be careful about where you put your tang...

 

Ok i looked at a few of my pistons and i see not all the tangs are on the same side so i think i get what youre sayin im gonna try tomorrow ill let you know how it goes. Thanks for explainin... next rebuild im definitely markin everything

 

Best thing you could possibly do of course, as Orange described, would be to figure out which piston came out of which hole, and put them back. I'm suspecting that's not a possibility.

Next best thing would be to lay them all out on a table, in the same orientation: let's say, with the front of the pistons facing up and the rod end toward you. Then look at the rod end and which way it's facing. You should find 4 with the bearing tangs facing to the left, and 4 with them to the right. The ones with the tangs to the right go in the driver's side bank and the others go ... you know.

Meanwhile, mic the pistons across their widest place (usually the center of the skirts about 2/3 of the way down from the ring lands, but sometimes right near the "tip" of the skirts) and see if they're all the same, within a .001" or so. If they are, you got lucky, and it won't matter so much whether they go back into the right hole. (EEEeeeeeewwwwwwwwwww)

You can also look for any kind of witness mark on anything that rubs against anything else, and find as many matches as you can. Marks in the bore that match marks on pistons and marks on the sides of the rods where they've rubbed against each other, are about your only options. Remember, for each match you find, you have DRASTICALLY reduced your chances of error; do the best you can, but don't get too discouraged if you get to the end and still have a question mark or 2.

When you put it back together, the rods should slide freely along the rod journals, even after both are on. There should be around .010" - .015" of clearance between them. You should be able to easily rattle each one along the rod that small distance. If you can't, something is still wrong.

Notice that if you just jam the cap onto the rod, it doesn't necessarily line up absolutely perfect. It'll leave a little step on the side that you can catch your finger on, and which of course can catch on the rod next to it. You want to align that "step" to eliminate it. To go back to the use of a hammer above, bonk the pairs of rods together GENTLY after both are on the journal on each side (both junctions), and before torquing them; tap both the rod and the cap individually up against its neighbor, to align that "step" to the flat surface the other rod presents. THEN tighten them. Oil the bolt threads, and tighten to about 25 ft-lbs, then bonk them one time real good with the hammer to "settle" them in place, then torque to 35 ft-lbs.

The engine should require NO MORE THAN 10 ft-lbs per pr of rods, and probably no less than 5 ft-lbs, to turn all the way over with your crank socket. (DO NOT use the damper bolt as a turning handle!!! else your next post will likely be something about "how do I fix a stripped damper bolt hole in the crank") Each pr should add about the same amount. I.e. put on the 1st pr, it takes 8 ft lbs; put on the 2nd pr, it takes 14 (6 more); put on the 3rd, it takes 21 (7 more); put on the last, it takes 27 (6 more). Something like that. NOT, it takes 8 after the 1st pr, then 100 after the 2nd. If you get into a situation like that, STOP and figure out what's wrong.

Put the bearings and caps (MARKED with something that won't dissolve!!! Test it first!! A "toe tag" works for example, but writing on the parts with a Sharpie or something will NOT) in a shallow pan filled with clean new lacquer thinner. Dip the pistons in a coffee can or the like, also filled with clean new lacquer thinner, turn them around backwards and dip the big end into the thinner as well to clean it, and set them on a clean white towel to dry. (change the thinner if it gets noticeably oily or dirty) Immediately before putting each rod/piston assy into the motor, take its cap and a bearing set out of the thinner, set it on the towel to let it dry, squirt a SMALL amount of 2-stroke oil onto the rings and smear it all the way around, align the rings with one oil rail gap over one skirt and the other over the other skirt and the expander ends about halfway in between, the lower compression ring with its gap over the skirt that the lower oil rail is over but not directly in line with it (like, one 45° around from "centered" one way and the other 45° off center the other way), and the top ring opposite the 2nd ring. Pick up one CLEAN DRY bearing and put it in the rod WITHOUT TOUCHING the surface with your fingers, and another bearing and put it in the cap. Set the piston down, and immerse your ring compressor in the thinner to clean it up. Take it out, let it dry, put it on the rings. Using a clean lint-free towel, wipe the rod journal down with clean lacquer thinner. (spray can carb cleaner also works well for this) Put a few drops (doesn't take much) of your synthetic oil or ATF on the crank before putting the 1st piston on the journal, covering the whole journal so that it's ready for the 2nd assy of the pair. Put pieces of thin rubber or plastic tubing over the rod bolts to prevent accidentally scratching the crank, and install the 1st assy to that journal. Put the cap on, tighten the nuts lightly, just enough to hold everything together, and put in the 2nd rod/piston assy the same way as the 1st. Then align, tighten, and torque everything as described above. Check the rod side clearance and verify that it's in the range I gave you up there and that the rods are both free to slide along the journal. Check the torque required to spin the engine and verify. Then AND ONLY THEN, it's ready for the next journal's pr of assys.

 

Spent all day but me my dad and a buddy got it right. The problem was the rods were backwards. It spins with little resistance and they have slight movement. I really appreciate all your help guys

 

 

I never disagree with you but are you saying a short block's rotating assembly should take a minimum of 20 ft lbs to rotate? I usually check it on all motors I build and it's lower than that. I'd think much above 20 ft lbs is actually a problem. I don't even think it takes 40 ft lbs to rotate a long block minus the spark plugs.