Rebuilding LQ1 for Dummies: ROTATING ASSEMBLY

[Mach10]

I originally had one uber-huge post... But for simplicity, I've broken it up.

The story goes that I've damaged my motor as outlined in my previous post. yada-yada-yada.

I'll either be rebuilding my exisitng motor, or else buying another 91-93 junkyard motor and rebuilding that. Depending on internal damage.

This post refers to questions I have about rebuilding pertaining specifically to the rotating assembly:

1) The motor will be stripped down to bare heads and bare block. The block will be sent out to be boiled, and bored. I'm not planning anything major in terms of an over-bore. 010 or 020 over just for wear repair. The crank and rods will be cleaned and checked, and machined. I'll probably have the whole assembly balanced at this point. New bearings for everyone! I'm also considering having the rods polished and peened. Anyone had any experience with this? I can do the polishing myself (I LOVE working with metal ), but I'll have a machine shop do the rest

2) Here's a big question: What are the INTERNAL differences on the rotating assembly between the AUTOMATIC motors and the MANUAL motors? I am running an "automatic" motor through a 4-speed manual with a hacked stock 92 ECM. I've heard all sorts of conjecture, but the one that keeps popping up is "Thrust Bearing." Since the manual transmission doesn't have a torque converter to absorb torque-shock spikes through the drive-line, it seems to me that I might be accelerating wear on the rotating assembly. Should I source out a manual crank for it? or can I modify the existing hardware?

3) The heads will be ported and polished. I'm getting some guidance on this from an old hotrod friend of mine (the machinist, actually). A pro port and polish will be quite expensive, so I'll probably just pay him to look over the heads, and get professional guidance. If by some stroke of luck my valve-train is still useable, I'll have the valves and seats machines, and I'll lap the valves myself. The machinist will deal with the valve-guides (knurling, new seats, whatever). I love playing with die-grinders, and the way I figure it, if I have some lessons from a pro (not to mention some flow-bench data) I can't lose

4) The cams will likely have to be reground anyway, and since I now have a fuel-efficient beater, I'm seriously debating a better-than-stock profile change. I'm not convinced on the stock-cam timing "tricks" (13º retard, 8-8 etc)since nobody seems to have any data other than ass-o-meter speculation. Nor can I find any good cam info that I can plug into DTD2K3 to check the math. Anyone that has some info (dyno sheet for example) on this, or with any other cam change (commercial or custom, doesn't matter) can chime in now

5) Piston selection will be tough. See, I'm seriously considering a turbo for this motor (nothing uber-fancy... Just a T-4 at 6-8psi), so I'll probably leave compression alone (or lower it a hair). I'd like lighter pistons, but am wary of hypereutectics since I hear they don't fare well under any kind of boost. Anyone have any experience with a decent forged piston?

[SappySE107]

Only the pistons are different for the bottom end.

We are working on getting 96 cam specs. If you want to have a set of cams (just 1 bank) checked using cam pro plus, you will have all the specs you need on the cams. Ive timed more than 5 cars and can tell you that you don't need a dyno to notice the difference with the cam timing.

Hyper pistons are fine with moderate boost. They don't take well to detonation so if you plan to not tune the car, get forged. Otherwise, you would be fine with hypereutectic pistons.

[Mach10]

Anyone know to what tolerance the factory balance is set to? Is the assembly balanced together, or did they just weight-match the rods?

[fatman85]

does any one know where to get bushings to make 350 chevy rods fit the smaller 60v6 wristpins.
thanks in advance
....................
Jason

[series8217]

Anyone know to what tolerance the factory balance is set to? Is the assembly balanced together, or did they just weight-match the rods?

As far as I can tell from disassembly of my motor and inspection of all the parts, they spin the crank. THAT IS ALL. The connecting rods are AS-FORGED & sized as far as balance goes.

I personally balanced my motor and some connecting rods were off from each other by more than a couple grams.
The crankshaft itself needed the most work, though. It is important that bob weights are used while balancing the crank.
Make sure the rod small ends and rod big ends are matched independently; don't just match the whole rod!
If everything is within .5 grams and the crankshaft is properly spin balanced with bob weights and the flywheel, and then the pressure plate is added on and drilled to maintain the proper balance, you're all set. My motor does not vibrate as high as I've taken it (7150 RPM where the fuel cut off activates). You can put your hand on the intake and rev the motor to redline and it will NOT vibrate. I am not kidding! The bottom end of both you and your motor are soo much happier like this.

[Mach10]

Thanks for the info. The machine-shop I'm taking my bits to has a great reputation, and they have already told me they are doing separate big/small end balancing.

The crank will be bobbed, don't worry

I want my tolerances tight. Not because I'll be spinning it past 7100rpm... But mostly for peice of mind. A strong, well balanced bottom end gives smoother running, wears slower, and you get less harmonic distortion from the crank which translates into less stress on components, and more reliable valvetrain motion (which the rubber timing belt dampens to some extent anyway).

I will also be deburring and polishing the rods, and removing casting-flash from the crank. There's no facilities in the city to shot-peen, but removing the stress risers and subsequently losing a little weight, while INCREASING strength... Unless I screw up, there's no downside!

Obviously, this will be done before the balance. and I won't be touching the balancing pads. Will probably need them when the rotating assembly's being done.

Do you know the exact sizing for appropriate ARP fastners? As I see it, the very weakest point on this block are the rod bolts. Some good high-quality ARPs will make me pop a redwood in my pants, I'm sure.

[OldSkoolGP]

Boy, it's great more people are finally realizing this. We used to have some trouble makers on here who swore doing such work to your motor was a wasted investments because the stock internals were fine. But I doubt stock internals would have held up to the 9000 RPM I accidentally threw at my motor one day.

[series8217]

Thanks for the info. The machine-shop I'm taking my bits to has a great reputation, and they have already told me they are doing separate big/small end balancing.

The crank will be bobbed, don't worry

I want my tolerances tight. Not because I'll be spinning it past 7100rpm... But mostly for peice of mind. A strong, well balanced bottom end gives smoother running, wears slower, and you get less harmonic distortion from the crank which translates into less stress on components, and more reliable valvetrain motion (which the rubber timing belt dampens to some extent anyway).

I will also be deburring and polishing the rods, and removing casting-flash from the crank. There's no facilities in the city to shot-peen, but removing the stress risers and subsequently losing a little weight, while INCREASING strength... Unless I screw up, there's no downside!

Obviously, this will be done before the balance. and I won't be touching the balancing pads. Will probably need them when the rotating assembly's being done.

Do you know the exact sizing for appropriate ARP fastners? As I see it, the very weakest point on this block are the rod bolts. Some good high-quality ARPs will make me pop a redwood in my pants, I'm sure.

Sucks about not having shot peening locally, but you could just send out the rods..
We didn't do anything to my rods except balance, resize, and install ARP rod bolts. The machinist didn't feel it was necessary to shot peen them. We did shot peen the block though One thing I forgot to do that I regret is smoothing the sharp edges at the bottom of the bores where they enter the crankcase. There is a fairly sharp edge along two parts of each and while they aren't where the piston skirts pass (which would be VERY bad) they are stress risers and a cracked block does suck. Note that I am using Sealed Power pistons; the skirt doesn't go all the way around. It may be an absolute necessity with your build to soften those edges if you have a piston with a skirt going all the way around.
As for the ARP fasteners, I know the ones for the 2.8 are what you use for the connecting rod bolts. They are the same for the 2.8, 3.1, 3.4 OHV, and 3.4 DOHC. You can get them from summit.
It's my understanding that ARP head studs for some motor work for the main bearing caps, but I just used NEW GM fasteners (do not reuse head or main bolts!). You'll have to go to the dealer for the GM main bearing bolts. You need 7 that have the studs for the windage tray, and one without. The stud on the 8th bolt interferes with all of the aftermarket oil pumps so you have to use the studless one in that position. The bolts are only a few bucks each.