ST300 Torque Converter and Flywheel Question

[jsboots]

Newbie to the site. Just purchased numbers match 65 GS 48k miles. Motor and trans are removed due to cam install. It appears that either the flywheel is incorrect or the converter. Previous owner received one of them wrong over 10 years ago when he picked up the motor from the shop.

Now I am trying to piece back together. My flywheel bolts up as it should to the crank but the flywheel bolt pattern does not line up with converter.  The 3 hole pattern on the flywheel is 11.50" diameter and the converter is appx 10.75" diameter. Over all diameter of the converter is 13". I thought the ST 300 used an 11" converter but if that is the case my flywheel will be way off.

Any help would be appreciated as my local transmission shops are limited with info.  I am attaching some pics to help illustrate my dilemma.

[WkillGS]

The correct flex plate has 2 sets of converter mounting holes.... one for the larger full size Buick converter and a set for the smaller converter used in the GS.
Most 65-66 flexplates have the flexplate with 2 sets of mounting holes.
You can drill yours to work if you can't find a correct replacement.

Flexplate often has other holes drilled in it to fine-tune the engine balancing.

Welcome to the site and congrats on the GS purchase!

[GS66]

Yes, congrats on the GS! Can you post a picture and where are you located?

[Dr Frankenbuick]

It appears you have the correct converter with the  larger converter flexplate. Remember to line up  the index hole in the flexplate with same on crank or you will have balance issues. As Walt pointed out, you can drill your flexplate to fit your converter. Below are some pictures of the correct converter and flexplate:







Sent from my iPhone using Tapatalk

[jsboots]

I am located in N/E IN near Lagrange. Attached is a pic as it sits. It was built in Fremont CA plant. No PS or brakes.

[GS66]

I like it! Looks nice red with the molding packages!

[elagache]

Dear Walt, Jim, Good Dr., and 65GS.com welcome wagon . . .

Welcome jsboots to the 65GS forum!

You've got one lovely car there! 

Would you have any more pictures that we can enjoy?

Cheers, Edouard 

P.S. And don't be afraid to drop a first name, we are a very friendly bunch of car guys around here!

[Mark Ascher]

Welcome to the forum - nice looking car!
Interested in the cowl tag info (pic) for us Fremont car nuts.

Mark

[Rollaround]

JSBoots,
Welcome to 65.com, great site, lots of knowledge here.

Some of us 65.com guys and gals are having a get-together in Defiance, Ohio (about an hour east of you) on 10-11 Sept, you're certainly invited. Should be 10 or 12, 65 GS here. Best of all there will be be some great car folks and lots of 65 Buick GS knowledge here. I have two ST300s with converters and flex-plates on my work bench, a 401 on an engine stand and a 65 vert spread out over two or three garages. Bring your parts and we can check things out. With or without your 65 we would enjoy meeting you in person and sharing stories. 

By the way there is ample room for trailer parking.

Check it out here   http://65gs.com/board/index.php?topic=2951.0

Again welcome aboard.

[WkillGS]

Found a pic comparing the big car flexplate to the GS one. You can see the extra set of holes for the smaller converter.
The other various holes were to fine tune the balance on the engine.