Gas to Diesel in 73 trojan express

[Donald]

I have a 36 Express Cruiser with 440 Chyslers & want to change them with 6BT Cummins which I have already purchased. Has anyone done this re & re.
Thanks
Donald

[prowlersfish]

Donald , I asume you have a F36 sedan ? I have a F36 that had the 440s and now has the Cummins B (300 6BTA) maybe I can help with some Questions. Also danny put 2 250 Bs in his F36.

what HP are your cummins ? and what trans do you have for them ?

[Donald]

The boat is a 73 Express Cruiser Tri Cabin. The Cummins are 165 6BT & the transmissions are 72 series Borg Warners. I've been told they will work with the lower hp engines.
Thanks Donald

[prowlersfish]

"Express Cruiser Tri Cabin" ?? Never heard of that one But Know what a tri cabin is you have 165 HP cummins 6BT ? most marine BT are 210-220 ( there are lower HP like yours just rare)
BTA are from 250-370. What Year are your engines ?

How fast are you planning on going ? at 165hp you could have issues getting in plane .

The velvet drive will work one the the engines but to fitt the engines under the floor you may need down angle gear boxes .

are the gears on the engines now or the ones in the boat ? as you may have issues on oposte rotaion for the props , only some velt drive will reverse the rotaion for forward use ( full power rating)

[Danny Bailey]

Donald, I made the swap two winters ago and the posts are still here with pictures. Paul is right about the vertical clearance....the Borg Warners may put those Cummins right up through your floor. I used 10 degree down angle ZF 220a's.
Danny

[rossjo]

The 6BT's are not aftercooled .. the 6BTAs are. What injection pumps? Lucas CAV? If so, you can get 200+ HP with them, but will need after coolers.

I agree that planing this big hull with 330 total HP will be a challenge, but cruising at hull speed (around 10 knots) will be wonderful, economical and safe!