318 to 360 swap and trans compatibility

[Sonny]

I purchased the 360 today. Now I have a 1970 318 to remove and install a 1978 360 and bolt to my 1970 904 trans. I keep hearing that the 318 has internal balancing and the 360 has external; thus requiring a new balanced trans flex plate. Is this correct? If so, is the flex plate swap easy to do in the driveway? Where do I get one? Is that the only modification required?
Thanks for any input.

 

[BeeKool]

What is the 360 from? An auto or manual transmission?

 

[RT K_line]

I thought the 360 is balanced with a triangle weight on the torque converter. I didn't know standard trans engines were different.

 

[PurpleBeeper]

I haven't run small blocks in a LONG time, so please double check what I say (maybe ask Rumblefish on this site). I do believe that 360's were externally balanced. My first Mopar had a 360 and that seems to sound correct.

Now, externally balanced engines (in general) could be externally balanced with a weighted harmonic balancer, a weighted flex plate/flywheel (maybe a torque converter too) or both....basically at the ends of the engine. (FYI- big rod '70-71 440 six packs have both, balancer & flywheel).

I don't know about the harmonic balancer, but you likely have that on your 360 already. You "might" just need this weight (MAKE SURE TO CHECK SINCE I DON'T KNOW FOR SURE). It looks like it takes the place of a weighted flex plate or weighted torque converter to do a 318 (all internal balance) to 360 (external balance I believe) just like you're doing.

FORGET THIS LINK & LOOK AT CRANKY'S - He's correct and I'm wrong on this one
/qti-rm-531?seid=srese1&cm_mmc=pla-google-_-shopping-_-srese1-_-quicktime&gclid=EAIaIQobChMI0L7g5buY1QIVh7rACh2uzwYVEAYYASABEgL3tvD_BwE

Here's another link from FABO that might help:
http://www.forabodiesonly.com/mopar/threads/360-internal-or-external-balance.48598/

 

[PurpleBeeper]

I thought the 360 is balanced with a triangle weight on the torque converter. I didn't know standard trans engines were different.

Yeah, that's sounding familiar RTK.... don't quote me on this, but I think that's a 340 issue(?). I seem to remember that in '72-'73 the 340's with automatics went to a cast crank that was also externally balanced somehow & the '72-'73 340 4-spd cars got the older forged, internally balanced crank... I think.

I also think the 360's were all cast crank/externally balanced motors.... at least the ones put into passenger cars.

Check in with Rumblefish.... I'm sure he knows.

 

[Bill Monk]

The 360 has a cast crank so is an externally balenced engine. The flywheel or flexplate has counter weights. The harmonic balancer is also different

 

[BeatersRus]

you can buy either,a weighted flexplate b&m ??
which allows you to run the same vertor you have.
or get a 360 torque convertor factory.
make sure you tell the parts guy what year the 360 is.

ps,if you have a good mopar friend,whos a welder,and another 360 < vertor laying around,
such as the one from the car the 360 came out of? was it a 904 or a 727?
you could swap vertors or
you can Carefully chisel the weight pad off one convertor and then reweld to your 318 vertor.
just make sure its the Same location and also remember that one hole is always offset on the flexplate,
when you go to reassemble.

 

[Cranky]

It's a lot easier to buy the weighted flex plate for the 360. Just make sure it has the correct bolt holes for the 318 converter. Looks like by your post, this is what you need.
http://www.manciniracing.com/19exbal360wi1.html

The cheaper (maybe) way is to buy the weights and weld them onto the 904 Converter and just use the stock flex plate from the teen.

 

[Sonny]

What is the 360 from? An auto or manual transmission?

Automatic.

 

[cudak888]

It's a lot easier to buy the weighted flex plate for the 360. Just make sure it has the correct bolt holes for the 318 converter. Looks like by your post, this is what you need.
http://www.manciniracing.com/19exbal360wi1.html

The cheaper (maybe) way is to buy the weights and weld them onto the 904 Converter and just use the stock flex plate from the teen.

Used the same exact flexplate when I swapped my '68 318 to an '89 360, forward of a 904. Bolted this onto the crank, dropped the engine in, install the bolts, done.

Doesn't have to be any more complicated or expensive than this for a stock swap.

-Kurt

 

[toolmanmike]

It's a lot easier to buy the weighted flex plate for the 360. Just make sure it has the correct bolt holes for the 318 converter. Looks like by your post, this is what you need.
http://www.manciniracing.com/19exbal360wi1.html

The cheaper (maybe) way is to buy the weights and weld them onto the 904 Converter and just use the stock flex plate from the teen.

Yes sir! All 360's were externally balanced. Remove the stock flex plate, replace it with the B&M unit and rock and roll!