Gen V Merc 502 build advice
 

Alright everyone, looking for some advice with regard to building up my Gen V mercruiser 502. I am contemplating going with heads and cam at first but don't really know where to start. I have been searching on here for days and can't find that much info so if anyone knows of any good threads please feel free to point me in the right direction.

Boat is a 93 Check convincor 251 with a Gen V merc 502 and bravo one drive. Motor has approx 130 hrs. since it was refreshed; perhaps 400 hrs total on boat. Only upgrades to motor right now are an edelbrock high rise intake, corsa silent choice exhaust with stainless risers, and MSD coil. Other than that, to the best of my knowledge all internals are bone stock.

1. What are the common upgrades with respect to heads/cam that people do, is it wise to buy the 525 heads/cam and upgrade that way or go aftermarket?

2. What route do people normally go with this motor?

3. I've read some things about running a cam so big you have to get dry exhaust, can anyone help explain this to me or point me in the direction of some information I can read up on?

4. What are some good brands to look at for parts specific to marine applications (cams, rockers, lifters, heads, etc.)

5. Are my internals forged or not?

6. Does anyone have the stock specs for cam/heads etc. and is the motor roller or flat tappet?

7. Any other comments, questions, or concerns that I should be aware of or you feel would be helpful

Thanks again guys,

Seth

Just did this to my Gen V last year, yes forged internals, not a roller motor and should be your first upgrade. Second, exhaust get some good manifolds with long riser if possible and get a custom cam. I'll post more in a bit.

Here is my setup, made 540hp.

-Gen V 502 converted to roller (basically the cp performance conversion "kit")
-Basically stock bottom end with, crank turned .010, stock rods, stock pistons .005 off the heads and block to square everything up align honed etc.
-scorpion full roller rockers
-088 heads, no porting, but port matched with comp cams springs retainers etc.
-edelbrock air-gap intake, shaved to match the head and block decking
-850 holley with HP500 flame arrestor, down one jet size on the secondaries from stock holley 80443 marine.
-Bob Madera custom cam LOTS of lift, mild duration.
-DUI 7000 Series stand alone marine distributor, no boxes for this guy...(deleted the damn spitfire engine management system)
-Stainless Marine Manifolds with standard risers
-assembled by Detroit's best kept secret, American Engine and Machine

Keep in mind you won't need most of the work I already had done if you engine is relatively fresh. My bottom end needed lots of work since I spun a main bearing. I sent you a pm and let me know if you need anything.

This guy does cams for just about everyone it seems. http://www.marinekineticsonline.com/. Bob is the guy.

A good aftermarket exhaust with long risers for your application, a roller cam setup, roller rockers, Hurricane single plane (just like dart that came on HP500's but cheaper), holley 800 or 850 carb, should get you 525-550HP.

This cam would work nicely in my opinion. http://www.summitracing.com/parts/HRS-120205-14/ I used a very similar cam in a 540CI, 9:1 motor, with the above parts. I had merlin rect port heads, not much better than the GM heads you have now. Engine made about 600HP and 620FT lbs. HP peaked around 5600 If I recall. I dont see why you wouldnt be able to squeeze 550 or so.

Your carb'ed 502 mag is a good engine, its just on snooze mode in stock form. The HP version of it, (465HP) of that era, was the same basic setup you have now, but a hotter flat tappet cam, roller rockers, single plane intake, and holley 800.

The 525 cam you speak of is a gen VI cam. To make it work in your gen V, you'd need a different timing cover, timing chain setup from a gen vi, and a retainer plate, i think. Not worth the hassle IMO. Its a nice cam, but isnt gonna tuck you in at night.

Hey your private message box is full, wonder how that happened ;)

Delete some, don't forget to delete sent messages too :)

BUMPITY.....


Any other input on cams guys?? Something fairly aggressive....

Thanks to everyone so far that has chimed in, I'm learning more than I could have ever wanted to haha.

comp cams 270 h extreme marine or isky 270/280 mega hyd..both great cams and really sound good..

I'd say based on psychic ability, this thread is about to make a left hand turn :)