Harmonic Balancer size

[reddog64]

So i got a purdy new small block 350 in my 78...

I've just about got the front end all tied up and back together and i'm looking at the old 6 1/2 inch harmonic balancer on the motor and it looks bad, and is 30 years old...

So i wanna replace it with a new summit racing one...

Do i need to stick to 6.5 inch or can i use a 8 inch harmonic balancer???
If i use a 8 inch one, will the pully off the old 6.5 inch one still fit...

(Dumb moment question) - 350 is internally balanced right... only the 400 is externally balanced... So I need to make sure to get the internally balanced harmonic balancer...

 

[muddermilitia]

hijack, but kinda on topic. Could a externally balanced balancer be used on a 350?

 

[4X4HIGH]

You can use the 8" balancer instead of the 6 1/2". The only problem you'll run into is if your timing tab on the cover is a welded on tab then you'll need to cut it off and buy a new bolt on tab for the 8" balancer. You will need an internal balanced balancer on any engine other than a SBC 400.

This is the balancer i recommend. http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM%2D161358&N=700+115&autoview=sku

Use this timing tab. http://store.summitracing.com/partdetail.asp?part=PRO-141-202&autoview=sku

Or this timing tab. http://store.summitracing.com/partdetail.asp?part=MRG-4598&autoview=sku

 

[reddog64]

You can use the 8" balancer instead of the 6 1/2". The only problem you'll run into is if your timing tab on the cover is a welded on tab then you'll need to cut it off and buy a new bolt on tab for the 8" balancer. You will need an internal balanced balancer on any engine other than a SBC 400.

This is the balancer i recommend. http://store.summitracing.com/partdetail.asp?autofilter=1&part=SUM-161358&N=700+115&autoview=sku

Use this timing tab. http://store.summitracing.com/partdetail.asp?part=PRO-141-202&autoview=sku

Or this timing tab. http://store.summitracing.com/partdetail.asp?part=MRG-4598&autoview=sku

Ya know what's funny...
That's the balancer and timing tab (red one) in my saved cart...
Will order tomorrow

What's the diff in the 6.5 and 8 inch? just size?

 

[4X4HIGH]

Ya know what's funny...
That's the balancer and timing tab (red one) in my saved cart...
Will order tomorrow

What's the diff in the 6.5 and 8 inch? just size?

Yep, simply size. I think it was a matter of limited space on some vehicles so those got the 6 1/2" balancer. All the trucks i've seen all had 8" balancers, (they have plenty of room).

 

[Mudstud]

Does the model year of teh engine have something to do with it? The 85 vette engine I ran for a weekend used a real small one. My older 69 model block and others used a big ol honkin thing. I thought it ha dto do with technology became better as the years went on. No need for a big balancer anymore unless you're running an older, not as tight engine. I dunno.