IMO that is not his best option, cost that he will never recoupe will get out of control fast.


Sell his current engine complete, has to be worth a few thousand at the least. Purchase a complete take out engine that has everything including exhaust, many will come on the market shortly. Send they engine out to be freshened or run as is if you trust the history.

I have seen take out complete 500efi engines on this site for 10k. He could swap it out the same day.

Start from scratch and he will learn a few things the hard and expensive way, there is just way too much and no room to save money in today's market.

The fly wheel will not work, balance will be wrong. And that is just the start, why torture urself?

Resale on a merc motor will always be more than any creature he puts together himself, and you will have well engineered accessories that work!

ZZ502 block already has the brass freeze plugs. Do a search for the other changes/alterations to make it performance marine friendly on this site. The list is not that long and very affordable. Forged internals on this HP crate motor make it very reliable.

What he said

Hey Richard !!

Yes, you will need to purchase a flywheel. I have (2) new in the GM boxes that I did not use. Make you a smokin deal.
You can use the stock Merc cooler. In fact, use the entire Merc marine set-up from the 330. I did just that. Pulled my 7.4L 330 Merc and installed a ZZ502 with all of the Merc equipment removed from the 330.

Additional items installed on the ZZ502.
1) 30lb. bypass oil valve
2) Iron flywheel
3) Holley 950HP mechanical secondary carb (optional but highly recommended)
4) Quality Marine flame arrestor
5) Quality Marine oil pan
6) Fel Pro Marine oil pan gasket
7) Cometic head gaskets
-------Optional stuff------------------
8) roller rockers
9) Marine tall valve covers
10) Bob Madera custom designed cam


Hey Kidnova (Bill), did I forget anything?
Ask Bill about the ZZ502. He ran the snot out of one in his boat. NEVER broken anything!!!!

Been about 9 years since the 7.4 was swapped out for the ZZ502 so I prolly forgot a bunch of stuff, but..... My 7.4 cooler was not enough. I ended up going with a Harden Marine with built in thermostat, good for 700 hp. Eventually changed to a 10 qt oil pan. I used the stock ZZ Holly 850, ZZ rockers AND ZZ cam for 4 seasons. 1st season I used the stock Merc exhaust, then changed to the Revolution exhaust. Think you pretty much covered it Richard !!

btw... the ZZ502/502 performed flawlessly for 4 seasons. It was a great engine,

87Magnum, You asked which marine exhaust I am using. See attached pic showing the Keith Eickert cast aluminum header. Water entrance to the exhaust is at the end of the header tailpipe. Maybe better explained, at the beginning of the rubber exhaust hose connected to the transom tailpipe.

Good looking engine!

KE's here too. Best bang for the buck. More so if a good used set can be located/purchased.

I may be wrong ,but if you read the fine print, engines from Summit Racing and Jegs are not covered for marine applications---- which means no warranty of any kind !!!


Jim :poopoo::poopoo: