Balance Shaft Engine

[GM TURBO]

Is there any problem running a balance shaft? I have a good line on a low mileage (200 miles) complete motor with a balance shaft. I've read a few posts - and they all have a different answer. Waller runs one in his Sy. BG says they are weak.

I know about changing the main caps. I was planning on converting to four bolt mains anyway so that isn't a problem. Is there any reason why I shouldn't run one? I'd like to build it once and do it as right as possible on a somewhat limited budget.

 

[Sy769]

I personally haven't heard of failures in a turbo app. even though I have read they are weak. I suppose looking at the block design that they are weaker but the real question is at what power leve will they fail?
I doubt that your wife will let you build a engine combo that will break a balance shaft engine. :wink:

 

[93ty475]

my sy block was replace with one back in the early to mid ninety's...i didnt know it until i tore it down to inspect it...they claim it makes them run smoother, but i couldnt tell a difference....someone said they are weaker because of the hole where the shaft bearings are...do you really think extra strength is needed there anyway? i'm going back in with it...they even did the splayed main conversion with billet caps...

 

[GM TURBO]

I doubt that your wife will let you build a engine combo that will break a balance shaft engine. :wink:

That is one thing I like about that woman.

Honestly, my goals are pretty simple. I'm not going huge - I just want something I can drive every day and not worry about. I don't care about the smoothness of the idle or anything like that - that isn't my primary reason for wanting this motor. I would like to run big boost (22-25#) and not worry about it coming apart. I'm not a big track nut. I don't street race. I would like to get low 12's high 11's - so there isn't a need for anything more. BUT, if this motor is more fragile - and people can confirm it was the balance shaft that caused it....I might look somewhere else.

I don't think I am going to have much into the machine work as there are very few miles on it. I'm gonna run Vortecs that I also got very cheap.

 

[Zac]

Dave--

Do you have a source a engines/blocks or is this a one time deal kind of thing? I have been kicking around the idea of trying to find a block for the rebuild of my motor instead of pulling the current block then the rebuild.

Are you going to do the rebuild in IL or are you taking your Ty out to Iowa?

 

[GM TURBO]

Well, my dad got this one. Yesterday when we were talking he had said he has a few 4.3 blocks. This one is complete - I just don't know for sure if I am going to use the balance shaft or not.

We are probably going to start building this one and have it ready to go. I'll have all the machine work done in Iowa and we will do the final assembly in his garage.

I can find out if he wants to let any of the others go. I am sure I can get you a good price if he wants to let one go.

 

[AXXE]

I have a balance shaft out of a boat. Has less that 100hrs on it. It's taking up space. Make an offer and you can have it if anyone is interested.

 

[myclone]

I dunno what kinda deal youre into Dave but I'll throw my .02 in the mix just for the heck of it.

Balance shaft block:

You got one already for cheap.
Cam selection is somewhat limited I believe (no big deal if youre staying mild).
Ive heard the blocks are weak and Ive also heard they are plenty durable :-? .
Slightly more money involved in machine shop costs if you decide not to use the balance shaft.

Non balance shaft block:

You can prolly get one cheap by doing a little looking.
Cam selection anywhere from mild to wild.
Proven to be fairly durable in all but the wildest builds (IMO).
Saves you a couple of bucks at the machine shop.

I personally would rather have a non balance shaft block even if its no more durable than the balance shaft one as there is less monkey business getting flung around in there to break.

FWIW.. Ive got 1 or 5 non balance shaft blocks laying around that you are more than welcome to if you will come pick it up or have it picked up. I learned my lesson on shipping heavy stuff a long time ago as the cost tends to give ppl strokes.

 

[GM TURBO]

I guess I'll put it this way.

I got the balance shaft complete engine with 200 miles on it for free.

Now, I also have some non-complete short blocks with more miles for the same price. Part of my dad's private collection of stuff I never hear about until I ask about it.

If I am going to remove the balance shaft - I'm going to stick with a standard (non-balance shaft) block. If there aren't any advantages - there is no sense doing it. If the only advantage is a smoother idle - it isn't worth it - personally I kinda like a lumpy idle.

The cam selection was another thing I had read - or lack thereof.

I have no reason to go big. I'm not going to try to compete with the fastest Ty awards. I don't have the coin to do that. We were just kicking around the idea of building the motor now and having it ready for the day this one dies. Really I have my choice of blocks and a couple cranks. Other than that - I am going to replace everything else. The other thing with this motor is it probably has L-35 rods...Will I stick with them or will I just pony up the money for something better?

 

[vortecfiero]

Ive had the code w L35 nat/asp for about 4 years. I had a mildly built
2 pc rear seal 1 gen 4.3 before it

my observations are this
it is sooo smooth
it PULLS from 3000 to 5500
it likes premium fuel (9:1 comp) and about 3 to 5 degs initial in a light car

how this will translate to a turbo setup will be interesting

 

[smeagol]

I didn't like 'em for 2 reasons

1- simplicity - same reason like myclone said - less stuff to worry about

2- strength concerns - i have no data that it's stronger or weaker, but i have seen most any 4.3 block out there, and have pictures of many of them. One of the areas the Bowtie blocks have some serious meat added is in the lifter valley. Methinks that if this wasn't a high stress area, they'd skimp on material there. Anyways, to me, the balance shaft blocks *look* significantly weaker, and has lots of material removed from that same area, compared to the original syty blocks as well as the bowtie stuff.

If i were in your shoes Dave, building a mild buildup, with a low mile motor in your hands... I'd go ahead and use it. Swap the rods/pistons... think about the main caps (big decision there). Or F it, do it cheap.. just swap the pistons, don't push for 10s, and it should last fine.

 

[rainmaker]

Dave,

Buckshaw used the L35 motor in the braphoon. I thought it was real smooth. I think you got to ride in it once before i swamped it. Even after degobah, that motor was still good.

Just my 2 cents.

 

[GM TURBO]

Thanks for your help guys. I guess with the amount of blocks and cranks I have at my disposal I might as well start with this one first. I do see it fitting into my financial and speed goals.

 

[92Ty#1524]

Are the cranks also interchangeable between the W balanced shafted blocks and our stock blocks?

 

[jwaller]

Are the cranks also interchangeable between the W balanced shafted blocks and our stock blocks?

yes. but you will want to be careful of the very very newest ones they may have a crank trigger on the snount by the balancer..

 

[nallj92]

hey guys,
i bought a balance shaft long block from a guy in Greenville, SC and he said he ran consistant 12's with no problems witha pt52 in a 2wd truck, he said he was friends in jery mccoy and jerry knew about the truck, it has forged pistons and good rods and just a 2 bolt main, i think they should be pretty strong if it holds up to 12's.
just my 2 cents,

i havent run it yet in my truck yet, been busy

peace,

justin

 

[GM TURBO]

Thanks for the info Justin. I have decided I am going to use it. For what I am looking to accomplish - it seems like this is going to work just fine. It is good to see someone has gotten decent numbers out of it. About the only thing I am going to do different is convert to 4-bolt mains - just for the insurance.

 

[davecalidad]

I mainly built the Balance Shaft engine because at the time I was just finishing up racing GM 3800's and I liked the smoothness of the shaft's on the street. You can't touch the idle smoothness with Low IMP injectors and the F.A.S.T efi unit. Maybe a full sequential box would beat it. The mild cam RULES here!

I still run the 'Braphoon Long Block' in my 95' S10 and it's cranking out close to 580-600 at the crank, with a Precision Turbo and a custom 3" Exhaust System. Torque is tremendous...

The 'core' is a 1995 Blazer L35 engine, BTW. I'm running an early
(92) OEM L35 camshaft that had a 5,500 rpm redline. With the heads and biggish Precision turbo the truck makes power to ~5,800 rpms. I have Bowtie Main Caps, Eagle H Beams, and noisy TRW 2441 blower pistons in her @ .0045 piston to wall.

We didn't get our McCoy intercooler in time for the GM Hi Tech Shoot so we had to dyno with the DeQuick Exchanger and a White Racing Liquid to Air modded Garrett. Can you say MidNight Oil?

For street use this is an AWESOME setup. For RACE go no balance shaft and save yourself some time and money. McCoy has a handle on what will take what so give him a call before you machine the engine and get the right parts. Forged Pistons are a MUST! Quiet ones are a MUST for the Knock Sensor to work!

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[GM TURBO]

I was able to take a ride in the Braphoon before its voyage to the neverneverland that is know known as Degobah. It did have a nice idle and seemed to pull hard - even with the 20G.

I won't push it hard - just because I don't drive that way. It is nice to see the Braphoon has made it this far and survived Jerry for a few months of driving. I didn't realize until Jerry posted that it had the balance shaft motor - I really didn't know much about it at the time besides it was an L-35 motor.

Dave are you running Vortec heads or L35's?

 

[davecalidad]

I'm running some mild L35's with 2.02 x 1.60 Ferrea Valves. My nest engine with have either Vortec's or more effort L35's. Flowing heads as we speak!

If I was building a MAX effort 4.3 to run 9's I'd get a BOWTIE block. I'd run NO shaft.

That being said, I have little issue with the balance shaft engine for daily use up to ~600 hp. Being that a turbocharged engine is kind to a shortblock under cruise and off the pedal conditions it's not THAT big of a deal if we think the block is weaker here or there.

Now, I DO have Billet Main Caps, a FULL LINE bore and PRECISION balancing on an $80,000 balancing machine in my shortblock. It is VERY smooth up to the 5,800 shift points and combined with the Ported L35's that came on the engine makes for an alltogether different running engine that the a stock SYTY drivetrain. The L2441's are VERY noisy at .0045 piston to wall for about the 1st 20 minutes of driving, but other than this it might as well be a stocker!


A few Kettering, (GMI) engineers and I were bench racing the other night and the topic of RIP THE BALANCE SHAFT OUT came up. My 3800 customers on ClubGp do this in the 10 and 11 second cars. The shaft does INDEED work at all speeds and keeps some nasty 1st, 2nd and 3rd order harmonics at bay. Being that the 3.8 Grand Nationals and the Stock 4.3 V6's were designed to rev to about 5,200 MAX in NON balance shaft configuration we can partially see why GM went to the expense of installing a balance shaft in the 4.3 V6's and the 88 and newer 3800 engines. The balance shaft DOES work even after idle. Mercedes Benz and the REST of the world uses them as well. This isn't JUST ANOTHER GM band aid! Although it's easy to think that!

90& of the reason for a balance shaft is customer perception and satisfaction especially at idle and that last 10% may indeed help engine longevity at higher RPM's.

BOWTIE blocks are NON balance shaft. For ALL OUT racing no one is going to use a shaft!

But most of the SYTY builds I see are in fact street trucks. If I had a FREE 4.3 L35 I'd use it for sure! I would certainly use BILLET MAIN CAPS, EAGLE or OLIVER RODS, FORGED PISTONS, and PROBABLY one of Mike's Billet cranks.

True this seems like overkill on the street especially for a supposedly weaker block but I encourage anyone in the DETROIT area to come by for a quick ride.