GM# 3896966 (302 73) Harmonic Balancer [Archive] - Team Camaro Tech

: GM# 3896966 (302 73) Harmonic Balancer


jlighthart
Jul 5th, 07, 09:43 AM
I have recently purchased a 350 SBC motor and based on the following info,
VO511CKW, 3970010 block, I felt it was a 350. I have removed the oil pan and timing cover looking for additional supporting numbers. So far without removing the crank and a pistons, the only numbers I have found are on the harmonic balancer is #30 stamped on the top of each piston and GM# 3896966, 302 73, 2222H on the balancer. Even this is somewhat confusing as I have seen this # 3896966 balancer listed for use on early 67 SBC 302's (internally balanced motors) and for use on SBC 400's (externally balanced SBC's).

Questions:

1) Is the above 3896966 balancer an internal or external balanced damper? There are only two (2) drilled balancing holes on the back. There is no fat side thin side that I have seen pictures of on other 400 SBC balancers.

2) Where would the GM part # be located on the crank shaft and pistons/rods (if it's factory.

This motor was overhauled 5 years ago so I'm sure the pistons and rods may be replacement, at least the piston tops.

I'm trying to determine if this is really a 350, or is it a 400. So far the only part I have purchased and may not be able to use is a replacement harmonic balancer that I purchased for a 350 SBC.

Because of the internal / external balancing issue I'm at a stand still. I hope I can avoid a machine shop, but that still might be required just to figure out what type motor I have in hand.------ HOPING I HAVE A 350!-------

All replies and info would be of great help and appreciated. Thanks for all replies ahead of time.
John Lighthart Jr.
Charleston, SC

novaderrik
Jul 5th, 07, 04:58 PM
that's a 350 (or 302 or large journal 327) block that has been bored .030 oversize- that's what the "30" on top of each piston means. measure the stroke to see what you've got..
bring a piston all the way to the bottom, and measure how far it is down from the deck of the block.
3" makes it a 302
3 1/2" makes it a 350
3 3/4" makes it a 383 stroker- 350 block with a 400 crank.

jlighthart
Jul 5th, 07, 06:13 PM
that's a 350 (or 302 or large journal 327) block that has been bored .030 oversize- that's what the "30" on top of each piston means. measure the stroke to see what you've got..
bring a piston all the way to the bottom, and measure how far it is down from the deck of the block.
3" makes it a 302
3 1/2" makes it a 350
3 3/4" makes it a 383 stroker- 350 block with a 400 crank.


Thanks for a quick and simple check. I have talked to alot of chevy mechanics and none have given me better. It measures 3 1/2" making it a 350. Just for info do you have any idea about the 3896966 harmonic balancer I removed from the motor? It can't be both an external/internal balanced damper.

Thanks;
John