Well, lets be honest with ourselves here. How many times have you been into a motor at this junction? A tool is anywhere from $50 and up from there. This SBC only tool is less than $50 and has alot of favorable reviews. https://www.summitracing.com/parts/aaf-all96470 Are there more expensive tools out there that are universal? Definately!!! They are also 3x+ the price too. Again food for thought. If you think you'll ever be back in it again you'll be money ahead next time.

 

really appreciate the link!
I had no idea they could be had so cheap. I looked at some a few years ago and I feel like they were all well over $100

 

Timely link, thanks. I anticipate needing a cam bearing tool in a week or so.

 

Everything got delivered today(2 weeks early), I have to say I’m impressed with the quality of all the parts so far. It did come with a balancing sheet as you can see below.
there must have been a miscommunication because I thought I ordered flat top +3.7cc but they sent me flat top -5cc, which will still work with my combo. I can’t complain with a little extra compression. I have a stock deck height with .038 head gasket so I think quench will be OK.
I’ve never worked with some of the fancier parts of this assembly, rod cap bolts instead of normal rod bolts.
the clevlite bearings are dark gray vice normal light gray. All pretty neat.
So far I have to say GREAT value for money. Several hundred cheaper than buying it all individually and it comes balanced, saving more money.

 

I did not want to derail the OPs thread.
But if you engine savy guys could please comment on my 454 flywheel balancing question,
All replies are appreciated!

454 new flywheel balancing question

 

Have to say I’m thrilled with the scat assembly. I definitely would recommend it. Rips all the way to 6k rpm, not a touch of vibration. Haven’t hit it with the NOS or gone to track yet, but it better hold up.

 

Good to hear. Did you end up putting cam bearings in it or did you run it as it was?

 

I replaced the first one, but the rest were actually in really good condition.
taking it to the track Nov 17th, going to do some NA passes and then some with 125 shot. Gapped the rings 25 thou so plenty of room for more NOS

 

 

Hey guys, had some questions about rotating assembly balance.

I am building a 383 for a time attack track and street car, so sustained RPMs. Some quick build specs:
Cam is 232/236 at 0.050 duration
112 LSA
0.575"/0.575" lift

Heads are AFR Enforcer 195s with PAC Racing Spring 1.290" OD Hydraulic Roller Dual Valve Spring, 140 lbs on seat, .600" maximum lift, Max RPM 6300-6500(upgrades available).

Intake is either a Miniram or a TPI converted LT1 intake.

I would like to be able to rev this thing to 6500 all day on the time attack course. If the springs can be pushed a little, maybe even 6750?

Crank is a one piece rear main seal spec SCAT 9000
Pistons are Icon Forged 9914-030
Rods I believe are Eagle SIR

Going with a factory GM ZF6 dual mass flywheel and clutch kit. Using a stock TPI C4 post 1986 harmonic damper.

Question: I should get my rotating assembly balanced by a shop right? I was quoted $200-$300 for a balance job and that includes heavy Mallory metal.
What all items should I bring them as part of the balancing? Front harmonic damper, connecting rods, pistons, rings, bearings, ZF6 dual mass flywheel but what about the pressure plate and friction disc?

Thanks guys!

 

Piston w/wrist pin, one ring pack, one rod, one pair of rod bearing shells.....and you only take the harmonic balancer/flexplate if the crank is setup to be balance external......if the crank is set up to be balanced internal, no balancer or flexplate is necessary......and if the shop says it is, pull your parts and go somewhere else......

I had a 400 Pontiac assembly balanced at a shop in San Antonio in 2022 and they called and wanted the balancer and flexplate.....I said it was an internal assembly and not needed.....and they just continued to argue with me and basically telling me I didn't know ****....so I drove down there and asked to speak to the owner. He agreed with me....because I was 100% correct.........and they spun it up......I told the owner while the other ******* was standing there next to him that I had balanced over 200 crankshafts myself for World products and a balancer/flexplate was never even considered......I also told the guy that the next time I tell you something and you disagree with me I am just pulling the parts......
Point is, just because the shop tells you something....does not mean it is true......and there are no worse machine shops in this country for false info than here in South Texas....
Out of the 100 or so shops in this state that can even balance a crankshaft......about 4 know how to do it right.....some guy telling me they have to weld weights on the pressure plate to "balance" the rear of the crank........these guys say the clutch or pressure plate MUST be balanced to the assembly....ok, well how about the 4 million small blocks that had clutches put in them after the factory built them? Unbelievable the stuff I hear here.......]

You will never get to 6800 rpm without a $1000 set of hydraulic lifters....Titanium retainers....Manley profiled/lightened valves.....light rocker arms etc.....
Why not just do a solid?

Jebby

 

Those pistons are for 5.7" rods. The Scat 9000 crank for 5.7" rods will be VERY expensive to internal balance. No way worth the expense.

If you can go with 6" rods, and pistons set up for 6" rods, and the SCAT 9000 crank for 6" rods, you could get a stronger internal balanced assembly for a much lower cost. No mallory metal used here. This is the better way to go for the preferred internal balance.

I built an external balanced 383 with a Howards solid lifter cam 275/281, 112LSA, .505"/.520". Compression came out to be 10.75 and it runs on pump 93 just fine. Dart 67cc 180 heads and Mahle forged flat tops. Direct lube EDM lifters. Idle is choppy, but strong and it really rips when the RPM's come up. Very easy to drive around town so it is super easy to live with. I would not change anything.

 

I built a 385ci very similar to the one above but with a Howards Hyd. Roller......Dart 180 Pro 1's.....10.5 to 1....and a full Scat balanced external assembly and it runs as described above......VERY torquey......the Mahle forged flattop pistons had the thin LS ring pack in it and it was VERY noticeable how easy it was to spin the assembly with my bar.....I even had the owner come down and feel it......rings seated beautiful.....approx. 460hp/500ft/lbs. torque.....beast of a street small block.....

Jebby

 

I do not disagree in the sense that the balancer (damper) and the flexplate (or flywheel) are not "required" to be present in order to balance the "crankshaft", but, I will generally advise (not argue) that it would possibly be a better outcome as a 'revolving engine assembly' to have them made available.

In the instances of internal/neutral balanced crankshafts, I feel the proper procedure providing for this is that the crank is "spun" without these units, establishing the acceptable "balance" result, but then each is added into position and then each is individually corrected for any imbalance they may impart to the revolving assembly; thus establishing that they are truly "neutral", otherwise you're just accepting the accuracy in the effort of that vendor's workmanship, and ignoring the possibility of inaccuracies in the relationships in assembly. And in the instances where they are not provided, I sometimes wonder why should I try so hard in my endeavor, as this will be corrupted (to some degree) as just these items are added at the time of engine assembly.

As far as clutch pressure plates (friction discs are not applicable), if of the "Long-Stye" or "Three-Finger" (superior) type then these fall under the same consideration as this is quite a sum of mass as attached to the revolving crankshaft; others, particularly the ever popular today "Diaphragm" (cheap) types are not to be considered in the balancing effort due to their makeup, and the same for torque converters, as in these instances one will have to rely on the manufactures execution...........unfortunately.

It's all really about just how good of a job do you really want.

Scott.

 

Oh,...........and you might even want to provide the crank accessory drive pulley, as some of these with multiple sheaves and of larger diameters can get quite heavy and can impart a surprising sum of imbalance effect on the rotating assembly. If the shop says they don't want to mess with it, then you probably are at the wrong place.

And remember, if balancing this, be sure to prove a reference mark so as to always install the pulley in the same clocking in reference to the crankshaft And the same holds true for the clutch; but since Long-Style clutches are not common in GM products (except in some racing applications with aftermarket units) this might not be so relevant for most individuals on this forum.

Scott.

 

Even factory balance jobs can be improved upon for high rpm use.
IIRC the factory balance was around +/-20g.
Where a speed shop balance would be much tighter, say +/- 5 g? IIRC
And any non-factory part, like a piston, will more than likely be lighter than the factory part, necessitating a re-balance.
FYI My rods & pistons were 130g lighter.
I would think an aftermarket Scat pre-balanced setup would be fine. Crank, rods, pistons, rings, bearings. Change one part and you mess it up.

On the high rpm use, if you want it to rev past 6000rpm, and often, and not float the H- lifters, and thus tear up the rollers, I would switch to Morel Solid Roller Lifters, pin-fed ones, and run a tight-lash setup, on the milder hydraulic roller cam ramps. This is called a "hybrid" or "tight lash" setup. .006-.008" lash cold. It will be close to zero when warmed up.

You will need more spring to get that rpm, without float, than even an expensive H-R lifter can handle well. If they float, you will tear up the rollers. And lose the engine if you do not catch it in time. IE: more maint checks.

The solid rollers won't ever pump up and "float", the rollers will stay on the cam and not impact it and tear up, you can run slightly stronger springs than H-Roller lifters that keeps the roller on the lobes, and get more rpm, and the milder H-Lobes let you use much milder springs / more street friendly / than a S-Roller lobe. You will gain at least 500rpm up top before float on the same cam. Build it to handle 7k and it will run 6.5K all day without failure. With poly-loks you will hardly ever have to adjust the lash. Just check it once and a while to make sure it does not change.

Personally I would not run a S-Roller profile cam on the street. The much steeper / more aggressive lobes require much more maintenance, very strong springs, and more expensive valve-train parts. But if you want 7K+ you basically have no option. My race buddies shift their 640 BBCs at 8.5K. And they last. They have very expensive valve-trains. But they call 1000 x 8 sec runs a "long time". Their rings go before the valve-train.

 

Called the machine shop... they said to "do it right" they want everything including the front damper, flywheel, and pressure plate.

Hell I will probably bring them the friction disc as well!

And yeah crank pulley, I will throw that in the box also!

 

This being a GM forum I'm presuming that the clutch that you have is of the "Diaphragm" type, yes? If so, these are NOT to be incorporated into the balancing affair; and also not the friction disc either! And if the shop is inclined to be of an impression differently, then I'd be nervous if I were you.

In order to head off a dispute, that of my position on this subject, the reasoning is simple and understood by most; the diaphragm type pressure plate assembly generally will locate the 'pressure ring' to the 'hat' suspended on three offsetting spring steel straps (sometimes more); these do not locate the ring rigidly but rather allow a certain amount of floating movement, and its' rotational centering is a consequence imparted by the differential in the surface speeds in the clamping of the friction disc to flywheel in function. You can not very well simulate this on the bench and therefore the ring possibly/likely being offset from its' otherwise proper running position (if only due to the parcel carriers repeated dropping/tossing, from often significant distances), mounting it to the assembly for balance will present an erroneous value factored in and lead to a wrong conclusion.

And the friction disc is left out for the same reason of the difficulty in establishing its' appropriate functional running position.

Scott.

 

So when you go to replace the clutch or balancer you have to tear the engine apart to perform this? I'm sorry......but that is 100% BS. Out of the thousands of hand built engines using neutral assemblies.....never hear of one vibrating due to poor balance on the clutch, balancer, pulleys......C'mon.....Pulleys?!
It is actually counterproductive for the future......as now the assembly is balanced exactly to those pieces and anything else will throw it off......according to their claim of "Doing it right".
Eagle, Scat, Callies, Lunati......do not use your pieces to balance an assembly for you......and at the higher end levels.....the type of flexplate/flywheel, balancer are super high quality pieces like an ATI balancer......
The ******** who balanced my own 406 welded weights to the clutch......who does that? Did you add the weight to the clutch to balance it or to balance the whole assembly? How do you balance a balancer or clutch on a crank balancer? You can't! You have to balance it as a whole unit.....which is fine once completed but if your damper/flywheel are garbage to begin with......like an Auto Parts store clutch.....now you balanced it into the assembly......so what happens when you go to change this clutch later on?
In a perfect world you would balance everything together......10,000rpm 358ci small block you balance the pieces together.......6000rpm street engine? Not necessary....and I can say that after personally building and balancing over 200 cranks and engines myself.....
If someone won't balance my **** to my instructions....they will not be balancing my stuff.......and the "Do it right" shop above is only doing it to limit the liability of someone bolting POS equipment to a balanced assembly......

I probably balanced and prepped about 100 540/555/565 cranks to neutral.....no balancer or flexplate and never had anyone ever call me telling me it shakes......in the real world, you are going to have to be more than 50 grams heavy or 25 grams light on a crank bobweight to make a difference.......actual to sheet......

Let me ask you this.....do you think that a 7000rpm Coyote 5.0l has the assembly balanced all together? How about an 8800 rpm S2200 Honda engine? You think Honda balanced all that together? The legendary LT-1/DZ 302?
I spin my LS powered Silverado with 180,000 miles on it to 6000rpm almost daily and never a vibration......not balanced together......

You really want to do it right? Spin the assembly neutral as explained with no damper or flywheel.....then have those pieces dynamically balanced at a balance shop......now, later on.....you take the new pieces and have them balanced too......but for most of us....it is a complete waste of time.........

Jebby

 

Well, the world is a less than perfect place; but the effort here is to better it as much as is reasonably possible (at least the first time out), after all that's what one may be striving for, and might be paying for; and as for unaddressed componentry as replacements being added later, how often does one replace a damper, yes it happens but.........? And as stated previously, as for the clutch for most you GM guys or converters your forced to rely of the part manufactures effort anyway.

No, actually the effect is not that the entire "assembly is balanced exactly to those pieces" (that would be the wrong execution), but rather the effort establishes that "those pieces" do not throw-off the balance of the assembly (excessively). Read my previous description of the process; quite different, if you think about it. And if the item examples you might happen to have initially are deviated somewhat from the targeted intent (though perhaps still within that manufactures "acceptable" tolerance), then bringing them closer to the intended value (here, neutral) may actually lessen the differential experienced when and if a substitute targeting the same (neutral) is added later. Right?! But yeah, now only as close as the parts' manufacture may provide, unless one chooses to pay to have a local shop check them; but at least we do know what the target intention is .............."0". This then leaving just the fixturing relationships as the unknown variable.

But this would be closer to correct, and it seems to agree with my presentation:

But seem to somewhat dispute the authors previous statements to some degree, yes?


And here, all I can say is, this presents a perfect example of why I stated previously that in certain instances one is going to have to rely on the manufactures effort................"unfortunately".

B.T.W. one doesn't spin ATI balancers, hubs yes, with inertia rings in place, no; this do to the same issue of the dynamic running locationing being different than that as received out of the box (and there are others).

The purpose here is to aid those whom seek at least somewhat accurate information, as that is the value here, particularly that of the technical side of this, or any other, forum.

Scott.