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I’ve been doing fair amount of reasearch, I wanted to know opinions on re using the rods and pistons from an 01 lq4. Trying to save myself from having to balance rotating assembly. Some people say change wrist pins. Some machine shops say if you use an arp bolt which is the weak point you have to re bore the rods out because they ovalize? So what are the main things I need to pay attention to if I want to re use the pistons and rods. Thanks
If doing a stock rebuild just to "freshen things up", I would re-use everything, but put new rings on them. The gen-3 rods/pistons are perfectly fine with a cammed 6.0L. You could even run a little boost without worrying about breaking anything. There's no need to upgrade the gen-3 stuff unless you plan on running lots of boost. If that's what you're doing, then balancing a rotating assembly should be part of the plan.
So currently in the truck I have a fully built 6.0 .30 over forged internals truck flow heads stage 3 summit cam etc. that’s where all my money is but unfortunately the oil has a ton of aluminum content so I have to pull it out. It’s my daily driver which is why I wanted to freshen up my running take out probably throw a better cam in it and leave it at that. Then I can use my resources on the other motor. No boost just NA I would like to find a better cam than what I’m using now. Probably use 243 heads and upgrade springs. Also I messed up on current built and my CR is like 9.7:1 so want to go higher on this build. So back to the stock gen 3 rods and pistons- there’s so much debate on using arp then have to recon the rods. Some people say replace the wrist pins. I was hoping to clean them up measure skirts i have two sets whichever ones better. New rings and set them back in with a hone(as long as machine shop says bores measure good) I don’t see why not. New oil pump dumbell just all the basics get it cleaned and honed then re assemble. Debating on even a new billet timing set or just getting a chain.
I just don't feel like it's even worth replacing the rod bolts in these engines they are just fine. If you really want to mess with the bolts on a stock rod I would consider having them touch honed. Does the bottom end even need anything, do you have any leak down or compression idea on it? One could probably just reseal it and run it for now till the good one is done.
Low oil pressure in cold which was pickup tube o ring. but no I probably should of left it together re did gaskets but had 260k on it and already popped it apart jumped the gun a little because feel like I’m on borrowed time with current motor
So if skirts measure ok, just clean up good new rings and rod bearings and send them back in? Are the bolts tty on these and how much wrist pin play do you guys usually say is too much? I know they flip around but most pistons do. I think slap has more to do with the skirts?
I don't see the point in replacing the stock rods or bolts with a stock crank, N/A engine. If you had a 4" crank in it, then you would be using aftermarket rods. Just put new bearings on the rods and main journals. The 243 heads should give you enough compression for a daily driver, even if you re-use the stock dished pistons. I would just put new rings and bearings on the bottom end. Then, top it off with 243 heads and a stage-2 truck cam. That's easily 425-450 crank hp in a well-behaved daily driver. Is that not enough?
Yes the lower end bolts are torque to angle not torque to yield. If the pistons are not great, but the bores are ok you might get by with some std flat tops. With the miles you are bound to have some bore irregularities but get it measured and see.
So Machine shop said 003 Taper and with a hone it would be out .005-.006 now it looks like I’m into balancing the assembly with new rods and pistons unless there’s a cheaper option. Do aftermarket oversized pistons like the OE ones try to keep the same weight? And can these rods take being pressed in and out again usually?
For the record i have a gen 3 lq4 that i had bored out .030” ovet and swapped out the dished pistons for Ls2 flat tops and gen 4 floating rods…..i did NOT have it balanced and put it all back together with a LSA supercharger on top of it all……that was 13k miles ago and she works just fine……..did the same thing with a Lm7 years back too, swapped out the dished pistons with 4.8 flat tops ….again without balancing, worked like a charm!!!……honestly if your building a stroker, or piecing together a rotating assembly from various manufactuers I wouldnt worry too much about balancing it!!!……but thats just my opinion and im sure they are gonna grill me on this FOR SURE!!!!
You can normally re-use rods with pressed in wrist pins. It's good to check for obvious damage after pressing out the old ones, as it is possible to gall the bushings if there was already warping/damage r just not being careful. A good machine shop should be able to do this for you without issue.
The aftermarket pistons are usually really close to the same size and weight. It's best to let the machine shop measure each new piston and match it to a cylinder. I had to do this once with D.S.S. Racing pistons. A few were about half a hair off from the others.
If you think about a high-mile stock engine, they usually have some excess oil and carbon built up. They aren't perfectly balanced anymore, if they even were in the first place. I believe you could take a brand new crate engine and still balance it better than GM. So, your question about balancing or not...I think it comes down to how much you are willing to spend, and what you expect out of the motor. If you re-use the stock rods with new pistons, then you would be better off balancing the engine, but it would probably still work without balancing. I think having a perfectly balanced motor is far more important in long-duration, high rpm conditions. With low RPM, regular street driving, you could probably get by without balancing. The pistons supposedly have less effect on balancing than the rods. If there is a big difference in weight going from the old to new pistons, then balancing would be a wise choice.
For the record i have a gen 3 lq4 that i had bored out .030” ovet and swapped out the dished pistons for Ls2 flat tops and gen 4 floating rods…..i did NOT have it balanced and put it all back together with a LSA supercharger on top of it all……that was 13k miles ago and she works just fine……..did the same thing with a Lm7 years back too, swapped out the dished pistons with 4.8 flat tops ….again without balancing, worked like a charm!!!……honestly if your building a stroker, or piecing together a rotating assembly from various manufactuers I wouldnt worry too much about balancing it!!!……but thats just my opinion and im sure they are gonna grill me on this FOR SURE!!!!
I would have balanced the LQ4 bored .030 over, especially with the LSA blower. With the LM7/4.8 pistons, I probably would have done the same as you. Some people will say you should always re-balance. I believe it's your money, and engine. Do with it what you want. If it blows up, you only have yourself to blame. It's all about risk vs reward. Everyone has a different level of risk acceptance.
Yeah I just know using old pistons with it being honed with end result at .005 in the bore will not be good at all. Wish I could find a cheaper set of 6.098 rods and use the speed pro pistons from summit (they seem ok) to be honest I just want a decent build to last while I pull this current build out and see what went wrong. High AL content in oil
Yeah, if you bore it .005", you will definitely need new pistons. Just make sure to measure every piston, because the cheaper ones tend to be a little off. I would just re-use the rods you have, and put new pistons in it without balancing. That should be fine for a daily driver.
It sounds like your other engine needs a complete tear-down. There aren't many aluminum parts that move in an engine. Most of the rotating parts are steel. The pistons are aluminum, and the bearings have aluminum mixed in with some other stuff. The aluminum in the oil is likely a bearing wearing out. It could be a piston. I guess you won't know until you get it apart. I hope you get that one sorted out. It looks like a nice engine build.
Ok thank you that’s the way I’ll go I’m going to press one out to measure the weight of the stock piston hard to find online. Then try to match up the best I can with 5 oversized and keep the gen 3 rods. And yeah unfortunately spent a lot of money at machine shop and parts on my current build kind of mad at machine shop for not helping out more with aluminum issue
So got block back from machine shop bored and honed 20 over stock 02 piston rods bolts and pin weigh 1228 grams the new ones 1243 on a couple most are 1247 grams with the new pistons. Couple questions as I’m tackling assembly myself
1. there’s a groove in rear of crank where rear main is machine shop said the new rear main should be fine but it definitely looks deep.
2. With the piston and rods 19 grams heavier do I need to rebalance or just try to take the weight off the pistons.
3. do you guys get away with re using your main studs/bolts. I know the side ones need sealant.
4. Also just concerned about re using rod bolts. Rather not pay the 55$ a piston to re size if using new bolts at that point would have just got new rods.
5. Do you guys like the c-3220 timing set?
Thanks guys!
Let me tell you my experience with re-using main bolts. Factory main bolts are torque to angle, but you can't do the torque to angle scheme the second time because it won't have enough clamping force. You'd have to torque to a lb. ft. spec. So I did that, but I was still uneasy about it ( my build may see 1000+ HP eventually ). So I just spent the $100 on new bolts and was done with it. Yours, being a mild build, I wouldn't worry about re-using them, just remember to torque to a spec ( lots of write ups and videos on how to do that ) and not torque to angle. Rod bolts, go ahead and reuse them. They'll be fine in a mild build.
I wouldn’t mind grabbing a summit main bolt kit. It’s just confusing if I want to check clearances and back them off and on that should be ok. But yeah I’ll just re use rod bolts it won’t be seeing 7000 rpm lol
02-18-2024, 12:22 PM
Re use Gen 3 Rods and pistons? 
