Will a 4.3 flexplate work on a 350 ?

[Dan Barlow]

Will a flexplate for a 4.3 work on a 350 ?

[Russell]

Do they have the same balance?

[STINEY]

Short answer - no. It will bolt on and function, but the balance is wrong.

There is a lot of debate on which flywheel is correct for the 4.3, some say a 305 one will work and some say its wrong also.

Here's the flexplate off my '94 4.3 in a c1500 truck, note the large balance weight.

[Barry Donovan]

the 4.3 is on its own.
crazy as an old 400.

305 and 350 play together.

[Dan Barlow]

The one I was going to give a friend, that was going to use it to break in his small asphalt oval cars new engine .Says he runs a 3 speed stick that has a small and different clutch pack and that all he uses the plate for is to start it . The one in I have in question says 763 and it comes up as a 4.3 153 tooth . I have another that is sitting on my garage art 350 which I plan on putting in my S10 with aT5 but ,since I haven't changed the pedals out yet , I hate to burn the bridge then a 700R come up and I'm up the creek . Maybe I'll let him have it with the catch that Iif I need one latter he can get me a junk yard one .

[STINEY]

I don't know if knocking that weight off would leave it neutral balanced or not. Have seen the clutch setup you described, its neat stuff.

[leleva]

the 4.3 is on its own.
crazy as an old 400.

305 and 350 play together.

As long as you have the dual bolt pattern for the starter bolt up. I made this mistake when I swapped the 305 ( Which had the153 tooth flex plate and straight bolt pattern starter I robbed off my 250 inline 6 on it) to a 350, which only had the diagonal starter bolt pattern for the 168 tooth flex plate. After trying to start the car and the bendix gear not being any where near the flex plate, I had to shove the trans back a few inches and swap flex plates.

[Dan Barlow]

Alrighty just in case this could help someone else down the line , The only difference is that hugh weight . Looking at my 4.3 flexplate it looks as though if I need to latter I cane get that weight off with a little work . That said , Im just going to give him the one off my 350 . Looks like this . Pic of each side .

[squirrel]

I used a truck 4.3 flywheel on a 350 in a TPI Vette swap I did years ago, worked fine.

I've heard all kinds of weird things. But if you look up the parts in question on one of the online parts places, maybe you'll get some useful info?

[STINEY]

I wonder if some of the conflicting info is innocent........perhaps it depends on if the 4.3 is an early model with no balance shaft = needs large weight, and the later balance shaft version didn't use weights?

I could see a later one interchanging with no issues.

[squirrel]

for example, look at this

http://www.oreillyauto.com/site/c/detail/PTQ5/NFW1023.oap?

and click on the "compatibility" tab

4.3, 305, 350, 1986-98

[Deaf Bob]

Friend drilled a chevy flywheel for his Olds 455, they are externally balanced.. Had to re bearing it every 15-20K miles
Using the balanced flywheel pictured will not be good.

[JamesMayberryIII]

Depends... what 4.3??
the v8, the v6, the v6 with balance shaft??

internal balanced engines have no balanced weights on the flexplate other than balancing the flexplate itself.. like balancing any think drum/rotor/tire .

[Dan Barlow]

4.3 in question was a V6 .

[STINEY]

Yes. The sawed-off small block version V6