340 Help

[340 Dart]

I have a 1973 340 I want to put into my 74 Duster behind a 904 transmission and I wanted to check with you guys before I bought some wrong parts.

This is an externally balanced, cast crank engine correct? (1973)

So I could use the B&M flexplate with the "bite" out of it?
How about a convertor? As long as its a non-lockup and fits a 904 it's OK?

Thanks for your help, I really don't want to screw this up.

 

[340mopar]

If you use the weighted flexplate you can use any neutral balance non-lock up convertor like off of a 318 car.


Chuck

 

[bobscuda67]

1967 and earlier 904s' use a different input spline count than 1968 and latter
904s'. They are not interchaneable.

 

[340mopar]

727's also have different splines some years so I guess I should have clarified that. So here is an update.

"You can use any neutral balance non-lockup convertor with the same spline count as your '74 trans or trans that you use."


Chcuk

 

[340 Dart]

Sweet.

Thanks guys. Hopefully I get a chance to to drop it in before December.

 

[340duster]

Make sure the flexplate is for the externally balanced 340. The 360 la and the 360 magnum one will not work. The all have a different amount of imbalance.

 

[ray79rt]

also make sure your 904 is non lock trans. the input shaft is different on non and lock up 904. They make a "dummy" non lock up converter to slide into a lock up trans or you can change the input shaft,front drum and valve body to convert a lock up to a non lock up.

 

[Guitar Jones]

You don't need to change the front drum, you need the correct reaction shaft for the non lock up trans along with the input shaft and valve body. There are different front drums but it gets a little confusing as to what fits what.

Basically there are 4 disc front drums with non lock up R/A shafts. Then there are 5 disc front drums for non L/U and L/U transmissions. The drum is the same but the reaction shaft is different. You can modify a L/U R/A shaft to make it a non L/U shaft by removing one ball plug. Compare to a non L/U shaft to see which one needs to be removed.

There are also differences in the rear clutch drum interface with the R/A shaft so be careful if you are mixing and matching parts.