Make a case for me, yes or no.

setup:
Stock crank, rods, and pistons.
ARP rod bolts
speed pro rings (stock 2.0/1.5/4.0)

I am planning on spinning this. Probably to 6,800 rpm or so.

Is it worth it to balance? I wanted to but I'm getting very low on cash for the project. I budgeted $2,500 for this build and I'm currently at $3,000 for a simple cam only with a refresh of the bottom end. I still need to get new valve guides and seals installed in the heads, purchase main and rod bearings, and misc gaskets.

I can put it off to save money, but I actually have time now to assemble the engine and stick it in the car. Once school starts back up and I start another job my time is going to be gone.

 

i would get it balanced. It wont cost you very much

 

I sure hope not, I was quoted in the neighborhood of $200 from one shop. Uggh sometimes I think I should've just thrown the 64k mile bottom end I bought in it without touching it, stuck a CC503 in with cheapo valvetrain parts and be driving it right now...

 

That's a tough one. You realize that the factory does not balance each individual rotating assy.? They do weight match parts but rely on everything being w/in tolerance for overall balance. At least it used to be this way on stock motors. I am guessing that it still is, but in any case I know it was once that way and worked fine. OTOH, if you do it and find out it's way off you will just have to tear it down again! Don't come back on me if I am wrong, but if it were me and $$$ were really tight I would try it. That's provided it was going to be my own labor to pull the motor and do it all over again if it was a shaker.

If you decide to not have it balanced, I'd be curious how it turns out, so let us know.

Rich

 

Yes, I realize the factory does not balance the assembly. my dad keeps saying just to put it all together as it is, he has done it plenty of times, and has reminded me the factory doesn't balance.

I do just about all the labor on my car. Only thing I don't do are things I don't have the tools for, and transmission work. I really don't want to tear the engine out again though haha. I've torn it out too many times. it is getting easier at least!

I'm also not sure I want to be a guinea pig!

 

The factory may not fully balance the rotating assembly. But, you have to remember the factory rev limit is set at ~5800 rpms, not the 6800 you are wating to turn. I would balance, just to be safe.

 

Before you read any further just remember...."free advice is worth what you pay for it", but, I will share a personal LT1 engine building experience with you.

Last summer, I helped my cousin do a "budget" LT1 shortblock rebuild on his '94 Z with over 100,000 + miles on it. Since it was a "budget" re-build this only entailed all new bearings, oil pump, rings, gaskets, etc., with the re-use of the stock pistons, rods, and crank. Since the only change to the entire rotating assembly was to be the new piston rings, we decided (correctly, I think), that re-balancing the engine would NOT be required.

During the course of this rebuild, however, it was later decided that my cousin wanted to upgrade his pistons to forged pistons, just in case he wanted to add a 75 - 100 shot of "spray" sometime down the road. Needless to say, he put this motor all together, and back into his car before he told me he went with new forged pistons. When I asked him if the forged pistons he bought were the same weight as the stock hyperutectic one's he replaced them with..............I got this blank stare.

Since the motor was now about and hour's worth of work away for being "fired up", he finished the installation while I called the piston supplier (Keith Black) and "discovered" that the forged pistons he went with were each about 40/45 grams heavier than his stock ones. Now, we both knew that engines are often slightly "over balanced" at the crank end, but, we now had built a motor that was definately "under balanced" by using those heavier forged pistons at the reciprocating end.

Convinced that we would again have to pull, re-build and now re-balance this motor, we nevertheless fired it up, just to see how "bad" it would "shake".

The motor ran "smooth as silk" all the way to his re-programed OBD I rev limit of 6,400 RPM.

I think your dad's on the right track here, the only really big/different thing you're changing in the rotating assembly itself, is the ARP rod bolts for the stock one's. Now I know that 6,400 RPM isn't 6,800 RPM, but really how much difference can there be in an ARP rod bolt vs a stock rod bolt, and, any difference in mass, is located at the rotating end of the crank, not the reciprocating end.

If money's tight, (and our experience is any guide), skip the re-balance. I think you'll be okay???

 

I'll decide and let you guys know, probably bring this thread back up.

 

thats a joke right, i will promise you that motor wont last long

dont be cheap, the factory does not spin to 6800. if you want your motor to last spend the few extra dollars now

 

Dan, can't comment on the longevity of this motor since it has only about 500 street miles and about 25/30 drag strip passes on it, but, I can assure you this is NO joke. The motor was built just as described above........and runs vibration free to the limits we can detect using just our un-aided senses.