Mopar Muscle Association UK

I am considering a engine transplant on my 74 dart hardtop auto, now on the road at long last, and enjoying some regular use around town

Next phase may well be a motor upgrade, will a 340 or 360 drop straight in, what are general perils and pitfalls of each, and what is engine availability like ... ive seen a few come and go on retro, rods etc ... car is to be a non-show daily drive/second car

thanks men

A 340 will more or less drop straight in but you'll be lucky if you can find one. I know theres been a couple for sale recently but that's extremely uncommon. Nothing wrong with a 360 and they are much more commonplace, but it will be lower compression And have smaller valves so would benefit from a piston & valve swap or an ideal candidate to stroke out to 408. You would need a B&M flex plate to get around the external balance issue, and you'd need to mod the drivers side engine mount same as for a 340.

thanks blue, just to ask why would 340s be less common/preferred ?

The 340 was the highest output small block, good compression, good head flow and a steel crank. They only came in performance models for about 4 years so far fewer made than the 360 which came in all sorts of mundane stuff for a lot longer.

ah thanks, good to know

same swap I've done. I went 360, easier to find, plenty of parts and drops straight in with the right engine mounts.

you will need a 360 torque converter and flex plate if you have a 318 904 combo and going to 727.

I went 727 and 8.75 rear end at the same time as well as converting to discs up front if you don't have them.

easy enough swap.

yep currently 904 with discs up front, 727 would be recommended then for an engine upgrade ?

Using the B&M flex plate means you don't need to change the convertor.

up to you I guess, 727 can handle more oomph

If you're looking for a small-block 727, I have two I don't need.

A rebuilt one and a tired one...

Do send PM if they are of any use/interest.

Good luck with the swap.

E68

If you change from an A904 I think you have to change / cut down the Prop shaft too.... An A727 is longer from memory.

Rear end will need doing...........I bet you've got a 7.25 out back?
Won't last long behind a healthy 360.

For ref A body 8.75 rear ends are like hens teeth in the UK.
So you'll need to cut down a B/C body one or import. Then half shafts need modding. Add a Sure grip rear to make the most of it.........your into 4 figures easily.

If you change the rear end or the trans you'll need to mod the differential. I don't believe the rear brakes are interchangeable between rear ends (someone will confirm). Then you'll have to contend with the internal/external balance issues as pointed out above.

I'd not discount the 904 box. I'd speak to Duncan Watts before you change it out. They can be made to handle serious power and are lighter than the 727. Just depends if it's cost prohibitive on parts and build.

Not to put you off.........just trying to show the reality of doing it.......

I.D. your rear end first. If your REALLY lucky it may have been done already and your ahead of the game.

If the 904 is in good shape it will take it, you can certainly build one to handle the power especially in a light car. I would worry about the rear end if and when you break it, yours is a later Dart isn't it? might well have an 8.25" axle which is pretty stout.

my 904 is in somewhat less than good shape, its fair to say ... my 318 the same, just developed a knock, hence thoughts of upgrading ...

yes, on a 727 swap you'll need the prop doing

its just a case of how far you wanna go.

do it bit by bit