Does anyone know the actual differences between the 2? I have found quite a bit of info on the merc motors but not much on the hawks. A few have said the hawk is just a 420 with a blower. Any truth to this?

Hawk ran higher compression and less timing than the merc. That gave it a different torque curve.

Not to hijack, but to expand...

Was quality comparable?

Did Hawk also build a 575?

yes, the two we rebuilt in the 90's were basically 420 's with bm 174's .

174s or 177s? I've read both guess I'll have to look for some numbers on the blowers

My Hawk 525 has a 250 on it. Not sure if previous owner upgraded it.

Must have been upgraded seems its a pretty common upgrade

Hawk 525sc's were Merc 420's with B&M 174 blowers.

Merc 525SC's used a lot of the same major parts as the 420's. Same block, heads, and cam. Merc ran lower compression 7.5:1 pistons, more boost and more timing. They used Weiand 177 blowers.

I have a set of Hawk 575s??? They have B&M 250s on top. I believe the previous owner upgraded the blowers.

So, were there two models, 525 and 575?

Merc 525 ran a Weiand 177. Hawk 525 ran a 174 B&M. Ocean Performance was the entire start of that with Bud and Craig.