Hello i have a stock 72 Duster with a 318 and 904 i plan on installing my rebuilt 340 with 400-475 HP is the 904 strong enough to handle the increase in HP and TQ or should it be beefed up or should i search for a 727 ??.

Yes, a 904 can be built to do your job and would be my first choice. If possible, source a 999 version for a core.

A 904 can be built to handle it, but an otherwise stock 318 spec 904, not for long.

I put a mild 360 in place of the 318 I had in an M body and it didn't take long to tear the ear off the front band, but that was a three piece sheet metal band, I believe the 72 has the 1 piece forged band, which is what I eventually swapped in after I lost the ear on the replacement band. Then it crapped out again with clutches getting wiped and I out an A833 in.

I put a 340 in front of a 904 in a 69 Charger. It was a lot of fun for a while. I really don' know how long it lasted, the guys that bought the 69 Charger wanted it way worse then I did. A few years later that 69 Charger ended up at our local dirt track in the hobby class. It had a big block in it then. Gene

Properly built with good parts, the 904 is plenty strong. I've been running a 904 in my Dart for many years running as fast as 11.14 while weighing 3,540+ lbs & high 1.40 60' times with the wheels up! A nice bonus with the 904 is that I've never seen one grenade like a 727 when the sprag gets hurt.

850hp 904

link

I always end up replacing them with 727 and peace of mind.