View Full Version : Repower from chevy350 to vortec v6

04-09-2003, 03:03 PM
" I have a 32' marinette cabin cruiser. I originally had twin Chrysler 318 engines. I acquired two crusader 350 engines that need rebuild. How much of the bolt on would fit the newer Vortec V6 block. Does the bell housing fit? I saw a post here that said the Vortec was basically a sliced off 305/350 block. Is this true? The original 318's produced 225hp. Would the vortec be a good match? How about longevity of the engine. I'm not a speed boater, I'm a cruiser. Typically running around 2000-3600 rpm. "

04-09-2003, 08:26 PM
"I'm not sure I follow your swaps completely, but I believe the 4.3 V6 will fit the bellhousing of the small block GM V8. The 4.3 is 3/4 of the 5.7 (350) GM V8, and based on that block.

But if you have two 350 V8's to be rebuilt, why go to V6's? Or are you planning to use the reverse gears from the Crusaders on the V6's???

As far as power, the HP rating will be close, but the bottom end torque will be noticeably less with the V6's. You'll probably need smaller props for the V6's, which will make them turn faster for a given cruising speed.


04-10-2003, 11:31 AM
" So economy wise, and low-mid range power, the trusted old V8 may still be the better choice, due to the V6 having to turn a higher RPM. Does that sound right? I was thinking of the v6 only as economically better, with its HP being close. I guess low end torque is more important than HP in this instance. SO, I guess the next question, Then is that the 305/350 block on the output shaft end is more or less unchanged from the 1970's to the 2000's. Correct? Is there a VORTEC 305 or is it just a 350 vortec?
Thanks again. "

04-10-2003, 01:50 PM
" A smaller engine doesn't always mean better fuel economy. I mentioned torque in the low-mid range because of the RPM band you operate in. There are also noise, wear and durability considerations when an engine turns faster. Personally, I much prefer a "loafing" larger engine to a revving smaller one, fuel economy aside.

GM changed the rear main seals in the small block series. Early seals are two-piece, later years are one-piece. Cranks, blocks and seals are not compatible between the two types, so things can vary when fitting a reverse gear for one or the other.

Vortec refers to the heads and intake design in many late model engines, including the small block V8 series. If your Crusaders are worn out but still have usable reverse gears, parts and accesories, I'd look into rebuilding them or replacing them with long blocks. Crusader also offers replacment type engines. Check the link on this site. "

dannie thomas
03-21-2007, 07:56 AM
"I have a 2000 model 4.3 vortec v6 hooked to a volvo penta outdrive. I am having a miss at higher rpms above the 3800 to 4000 range. I am pretty good with car engines but not real experienced with marine. I think the coil has been replaced with a automotive coil and I know that a miss is usually associatated with ignition and fuel. Didn't know if this coil would make the difference or if something else was off. please email me at [email protected] ("") Thank you"