Gen 1 350 - Balancers & flywheels ? Mix & Match ?

I have a dozen or so 327 / 350's torn down to rebuild . All of the motors had the flexplates and balancers removed . Most were missing but I picked up a pile of old crap to scavange through.

2 bolt , 4 bolt , roller , 1pc seal , 2 pc seal blocks and 2 stroker cranks.
I found where to get the adaptor to use a 2pc crank in a 1pc block.
I have pretty much figured out what parts to use where but I am confused on:

1) the differences between the 153 and 168 flywheels internal/external balanced

2) and the different balancers - 7" & 8" internal balanced - do they interchange ?
  I can see the external counterweights on the 400 style .

I think:

1)the 2pc cranks are internal balanced for the flywheel and balancer

2) the 1pc cranks are external balanced on the flywheel but internal balanced on the balancer .

3) the 400 (383) are external on the flywheel and balancer .

Can anyone shed some light on the subject ,

Thanks in advance , Ken(Ark)  

there are so many options in balancers....    and they mostly interchange..  

there are more differences that you can see with the casual glance...

there are several different locations for timing mark vs keyway location...

i have some of that info somewhere ... but i cannot remember...

remember... some of the chevys used timing marks that were on the normal timing pointer that is mounted on the timing cover bolts...  

there are later balancers that had more offset to the timing mark vs keyway...   and used a timing mark that you had to look straight down behind the water pump to see...

so you really need to match the timing covers and balancers...   actually they are torsional dampers...

they dampen torsional harmonics so when the cranks start twisting it dampens them before they become end game amplitudes..

i remember reading an article or a section in something written back in the early 80's or late 70's... about the difference responses to different rpm ranges in race engines...     they mentioned in the article about belt driven supercharged motors not needing much damping as the engine torque from the blower drive was a great damper...

i am too confused to properly answer your direct questions...  as there are so many answers...

people also used to cook their balancers to change the tuning...  i think that was done a lot in the corvair as they had a lot of problems...  and their belt driven cooling fan was just not enough to dampen...  at probably added to the problem as on some corvairs... the outer damper ring drove the belt... like 250 chevys

there are some people who build dampers.. that have multiple sizes of damping weights to dampen harmonics at various rpms...  

but all of this is now what you ask.. but it might be what you needed to know...  

Thanks Wayne , I think I am on the right path now . Here's a reply I got from a tractor buddy which may help someone searching the archives or just gerenal knowledge.



Posted by Bruce Dorsi on June 03, 2009 at 17:17:33 :
In Reply to: Small block chevy guys ? posted by Ken(Ark) on June 02, 2009 at 12:26:49:

The following info is from the 1988 "Chevy Power Catalog" printed by GMParts.

"Production crankshafts used with one-piece seals also require counter-weighted flywheels or flexplates for proper engine balance." (page 5-11)

"Dampers produced since 1969 have TDC timing marks which are 8 degrees farther advanced then 1968 and earlier versions. These early and late-style dampers require different timing pointers to correctly indicate TDC." (page 5-21)

"EIGHT-INCH DIAMETER TORSIONAL DAMPERS ARE RECOMMENDED FOR MOST HIGH-PERFORMANCE AND COMPETITION APPLICATIONS. (page 5-22)

"Production 8-inch diameter torsional damper is neutral balanced. Counterweighted damper is used with externally balanced 3.75-inch stroke crankshaft." (page 5-22)

"All small-block Chevrolet crankshafts EXCEPT the 3.75-inch stroke cranks used in the 400ci engines AND 1986 and later crankshafts with one-piece rear seals require neutral balanced flywheels." (page 5-24)

From the 1998 "GM Performance Parts Catalog":

"All small-block and V6/90degree cranks which use a one-piece seal require a counterweighted flywheel for proper engine balance." (page 74)

"The 6.75" cast iron damper is used on most 1969 and later 305 and 350 ci SBC's. It is recommended for V6/90* racing engines and V8 applications with limited clearance. 6.75" balancers have been used successfully on drag racing small-blocks in classes which permit the use of cast iron dampers. The timing mark is 10* before keyway center line." (page 74)

So, it appears to me that you can use either the 6.75" or 8" dampers that are neutral balanced. Only the 3.75" stroke crank uses the counterweighted damper.

Your externally balanced 168-tooth flywheel is what you need.