payuppsucker

Not terribly aggressive, lift is just shy of .700 IIRC. To be honest I think the rockers failed because of a misfiring issue I had earlier this year. The distributor cap was trashed and it was miring multiple cylinders. I guess I should have mentioned that in my initial post.

Full Force

iTrader: (5)

gotcha, sucks to hear either way

payuppsucker

At least it did tear anything else up. Back up and running so all is well.

turbos230

Why not get a tall deck 10.2 block and build you own 632 ci bbc.800 hp just from the cubic inches and no blower needed

cdail28590

iTrader: (2)

Not quite the 650hp as asked for but my 454 with good internals, hyd roller cam, 177 blower and stainless marine manifolds make 610 hp and starts and runs like a fuel injected motor. I would say not a high dollar if you already have the parts like I did but with better heads and a 502 you could easily hit the 700 hp and be very reliable.

midwest272

Big cubic inch tall deck , 87 octane , iron eagle 345 's spend money on valve train stability i.e. shaft rockers , high end solid rollers . Definitely carbed maybe a short tunnel ram with twin 660's , big tube etops

​​​​​​​keep rpm to under 6k , set lash once a year , enjoy boating

ToMorrow44

While a lot of boat motors are built like drag racing motors, you can't get too crazy with boat motors because they take much more abuse than a drag motor. You don't see a lot of boat motors over 565ci because above that, the wrist pins are way up into the rings and overall the pistons are weaker. Also a more aggressive cam = water reversion in a boat. Obviously exceptions to this using big aftermarket blocks with 5" bore spacing for more cubic inches, dry exhaust for water reversion etc $$$. Overall, boat motors are built like tanks, and tuned very conservatively. My motor is capable of 1000+ hp in a car, but tuned for 825 in the boat.

For the OP, 700hp is easy and relatively cheap on pump gas NA. Above 700, blower.

Tahoe540

I was only making an observation as I am new to boating and was used to seeing these huge cubic in motors. Believe me when I went to build my motor my machinist told me this would not be the same kind of build as my dragster and I have learned a lot reading on this site. I see a ton of expense and extra parts in blowers for big blocks and really don't see any issues with any kind of piston or any other motor parts these days with the high quality parts we can get. I see 6 page discussions on $200 valve springs and off the shelf cams from guys buying or rebuilding high dollar motors? I was also speaking to a pump gas motor and not a drag motor which can't use a high lift cam or lots of compression. Also on a pump gas motor you just tune it and drive it, you don't have to de-tune your motor. Currently for me I would love a blower since my high altitude lake is kicking my ass to make power and I have internals to take over 1500 HP but since this is my first boat I did not realize I have no space for blower pulley when I bought it.

hogie roll

If you're buying a dart big M why would you build anything less than a 598-632 with 800hp. All the components cost a similar amount.

ToMorrow44

On the 27 Advantages, they have 2 molds, one has a notch in the bulkhead in front of the motor to accommodate a blower pulley just for that reason. They probably didn't worry about that with your boat because nobody was using blower motors in those boats then lol!