Balancing new short block, GURUS please help!

[slowblackcar]

We are about to buy some parts for a new short block ( 109 block, stock crank and rods TRW pistons) and need some help from the Gurus. We are planning on buying a JW wheel flexplate and a BHJ balancer. Do most guys do a stock type external balance or an internal job? tell us how you have done it and what the pros and cons are, any input from those in the know would be greatly appreciated. Part numbers would help if you have them on what wheel to buy as well as the balancer. what percentage balance do you use?

thanks

Steve

 

[KendallF]

If it's a stock crank and rods, balance it stock style (external). I can't see the point in buying an expensive balancer and flywheel for this combo either, but what the heck..it's your money.

If you balance it at 33.3%, it will be fine at any rev limit that the parts will stand anyway. You can balance it at 50% for a little less total imbalance. If you do, it may require some Mallory metal which can get expensive quickly. My S2 rotating assembly required $170 worth of Mallory in addition to a $175 charge for the balance labor.

 

[Nick Micale]

Originally posted by KendallF
If it's a stock crank and rods, balance it stock style (external). I can't see the point in buying an expensive balancer and flywheel for this combo either, but what the heck..it's your money. ...............................

After seeing how some stock balancers have been badly worn and cracked as well as a "few" cracked flexplates, I would say it is a very good investment. A loose or worn balancer can easily ruin a crank.

This is on "Street" motors too, not just race cars.

 

[Jimn8or]

I agree with the comments thus far regarding the flexplate and balancing. If you are going to spend the $$$ on a balance job, spend the extra few more $ and get it done to 'zero' tolerance, opposed to the popular 2/10ths job that's good enough for Mustangs As far as the balancer goes, we don't actually run a harmonic balancer on these engines. There is no rubber ring like the SBC etc... and thus we don't need to comply with that NHRA 'rule' at any NHRA track. Having said this though, and knowing that our balancers slip onto the crank and rely on 219 ft/lbs torque minimum to keep 'em on, I don't know how to identify a loose or worn one as described above by a very experienced engine builder like Nick. Remember that there is no substitute for experience, and Nick has lots of it!
Jim

 

[slowblackcar]

Thanks for the replies.

This engine should make about 580 hp ( 109 block steel caps, champion ported irons, champion intake, PT-67, PTE front mount, 70mm tb, pte plenum, with all the supporting parts. We want to be legal to run 10's at the track and not have problems in tech. The NHRA never says a thing about rubber in a damper( there are many SFI legal units with elastometric rings), they refer to the material used ( no cast iron) and must meet SFI specs . We really dont want to put it together go to the track and have the tech guys hassle us over the damper.

Anyone have additional person experience on tech and the stock damper.

Once again thanks for the replies

 

[Chuck Leeper]

Cast iron??

The ft hub and pulley adapter are cast iron, and as such are not NHRA legal... The fact that there's no outer ring has no bearing on legality. It's the material that's in question. [SFI 18.1]
If you want to use a legal, steel hub, use a BMS hub for the stage 2. You will have to make a spacer for the pulley. [Kendall has one!]
I use the BMS hub, and a Race Jace alum pulley that he makes for use w/out the I/C fan.
As for the flexplate. There are 2 choices.. One such as a JW, or a Mondello "Reactor plate". The JW looks similar to a stocker, is better material,and it's SFI stickered. The Mondello looks like a clutch flywheel, and is also SFI stickered, The one I use weighs 11#. It has removeable wt on it, so it can be used w/ internal or externally balanced engines.

While on the subject of NHRA legality... You must also have a tranny shield, [SFI 4.1], to run 10.99 or over 135. SFI flexplate and flexplate shield, [SFI 29.1 & 30.1] is req'd for 9.99 and /or over 135. In order to "CMA", I use the CSI trans/flexplate composite shield. [Looks like KEVLAR]It's a 1 piece, bolt in shield that weighs 4#

Back to changin turbos!!

 

[KendallF]

Originally posted by Nick Micale
After seeing how some stock balancers have been badly worn and cracked as well as a "few" cracked flexplates, I would say it is a very good investment. A loose or worn balancer can easily ruin a crank.

This is on "Street" motors too, not just race cars.

Stuff must break a lot out there in the desert! I bow to Nick's experience as I haven't seen this.

Originally posted by Chuck Leeper

The ft hub and pulley adapter are cast iron, and as such are not NHRA legal... The fact that there's no outer ring has no bearing on legality. It's the material that's in question. [SFI 18.1]
If you want to use a legal, steel hub, use a BMS hub for the stage 2. You will have to make a spacer for the pulley. [Kendall has one!]

Chuck is correct..but I do think the rule was written with the rubber balancers in mind. I have never seen anybody tossed for a stock hub. You can't come yell at me though if you are the first, OK?

I have a beautiful spacer for the front pulley that Chuck made for use with the ATI balancer. Maybe if you pay him more than I did, he'd be willing to make another!

 

[Nick Micale]

Chuck, you must have mis-read the NHRA rule book?

NHRA requires all cars 10.99 and faster to have an SFI balancer. A modified stage II balancer will not meet this spec. An SFI flexplate is also required for 10.99 and faster "except some Stock and Super Stock classes as noted under class requirements".

We stock both balancers and flexplates meeting SFI requirements as they are installed on all local T-R's running 10's or better. These are checked at our tracks.

When you have a chance, please send me info on the CSI composite shield as these blankets are a real pain, thanks.

Kendall, if I could figure out how to use my digital camera, I would send you a pic of the latest stock balancer removed with the keyway about 1/2" wide and a crack down completely through the hub!

 

[slowblackcar]

Thanks for the replys . This is exactly what I was talking about.

The track tech guys know me well ( I had a 7 second '23-t altered for years) and I could get through tech at my home track but don't want to roll the dice at other venues. I have seen the BHJ unit and it looks like it works with minimal mods. I have used the JW wheel in many cars and they are local so that is what I am leaning towards.

Nick, what brand damper do you use?

Thank you all for your input this has been a good learning thread for all.

Steve

 

[Chuck Leeper]

10.99 ??

Nick said:
Chuck, you must have mis-read the NHRA rule book?

NHRA requires all cars 10.99 and faster to have an SFI balancer. A modified stage II balancer will not meet this spec. An SFI flexplate is also required for 10.99 and faster "except some Stock and Super Stock classes as noted under class requirements".

My comment on the balancer had no ET reference in it. U R correct: 10.99 or quiker.
I did say:
While on the subject of NHRA legality... You must also have a tranny shield, [SFI 4.1], to run 10.99 or over 135. SFI flexplate and flexplate shield, [SFI 29.1 & 30.1] is req'd for 9.99 and /or over 135.
In order to "CMA", I use the CSI trans/flexplate composite shield. [Looks like KEVLAR]It's a 1 piece, bolt in shield that weighs 4#


The info U R looking for on CSI can be found at:
www.csicsi.com

As for the BMS hub, It's NASCAR approved, and works for me!!

 

[geno]

I have a BHJ balancer now but didnt for 2 years on my stock block and ran 10,s and 9,s without it and never had a problem with tec or the stock hub. I alway thought the SFI balancer was because of the 2 piece balancers came apart on 10,000 rpm SBC.
I would alway show the tec guys it was a one piece hub and they had no problem letting me run with it. I was told that rule was because they had 2 piece harmonic balancers come apart and land in the stands You almost need a lawyer to read the rule book these days