SBC 400 flexplate to flywheel

[67weimann]

I'm an idiot so here it is. I picked up a SBC 400 from a guy to use while I build my new motor. My question is, it had a flexplate on it and my PTO is for a flywheel. Can I use my flywheel off my SBC 327 on the 400? Internal vs external balance thing right?

[Oldsquirt]

As you suspect, the 327 parts wont work. 400 is external balance and the 327 is internal.
Just buy the correct PTO. It's probably a lot cheaper($50?) than a 400 flywheel.

[tbanzer]

Why cant you use the flexplate in place of the flywheel?

[IMPATIENT 1]

Why cant you use the flexplate in place of the flywheel?
you can, but in general a flywheel is thicker so you'd lose alittle spline input on the pump by goin back flexplate

[67weimann]

Why cant you use the flexplate in place of the flywheel?
Flywheel is thicker and the pto won't sit all the way on the flexplate.
So...
Can I modify the pto to sit on the flexplate? The nub in the center of the pto needs to be shorter. I would prefer to have a flexplate. Less wait to spin around...

[DelawareDave]

Use the 400 flexplate, and your 327 PTO, and get a spacer that makes up the difference in thickness from the flywheel to the flexplate. They are about 3/16" thick, and are listed Rex's online catalog.
http://www.rexmar.com/page311.html
PN 242 207

[67weimann]

Use the 400 flexplate, and your 327 PTO, and get a spacer that makes up the difference in thickness from the flywheel to the flexplate. They are about 3/16" thick, and are listed Rex's online catalog.
I think I will go that route. Thanks

[67weimann]

That link is for the pto itself. Can I modify mine to work...?

[DelawareDave]

The part number I provided is for the Chevy Spacer. Look closer.

[67weimann]

I'm an idiot so here it is.
like I said, I'm an idiot... at 45 bucks. If I got ot buy something i'd just get the PTO for a flexplate for 52 bucks.
Now before I buy something, can I make mine work with a little tlc? There's a nub that sticks out in the middle of mine. That is what holds it from sitting flush with the flexplate. Can I cut that down to work?
edit: could I drill the entire center out like the ptos from the catalog?

[DelawareDave]

The PTO's are all the same thickness. The spacer makes up the difference in thickness from flywheel to flexplate. So buying another PTO is not going to resolve the issue.
If yours is anything like mine, the PTO protruding "lip" fits into the crankshaft counterbore itself. Without the thickness of the flywheel, for the PTO to actually tighten up against, there is a space between the PTO and the flexplate. The spacer makes up for that.
The female bore in the PTO is to center your driveline.

[curtis73]

I recommend getting a 400 flywheel and ditch the flexplate. Engines need the flywheel weight to idle properly and help absorb crank vibes. In a car, that job is taken care of by the torque converter, but I strongly suggest using a flywheel in a boat. There is no need for snappy throttle response, so why doom the engine to hard vibes and a high idle just to compensate for a couple fewer rotating pounds?
Do it right. Get a 400 flywheel.

[Ryan00TJ]

I recommend getting a 400 flywheel and ditch the flexplate. Engines need the flywheel weight to idle properly and help absorb crank vibes. In a car, that job is taken care of by the torque converter, but I strongly suggest using a flywheel in a boat. There is no need for snappy throttle response, so why doom the engine to hard vibes and a high idle just to compensate for a couple fewer rotating pounds?
Do it right. Get a 400 flywheel.
X2