Carbed 502 Mag Rebuild Questions
 

Ok my motor is out and I am finally ready to do the rebuild. My plan is to do a basic freshen on the motor: gaskets, rings, bearings, valve guides, valve springs etc. I have a lot of experience in automotove engines, and racing engines. I understand marine and auto engines are similar but different. My question is that I was hoping I could get some recomendations on good parts to use on the rebuild. Such as good rings, bearings, gaskets valvetrain parts, oil pump etc. Also I was thinking about replacing the cam, lifters, and valve springs with something better than stock. I do have a good set of stainless manifolds and the boat does have captains choice. It also has the stock quadrajet carb. Like I said I am not looking to go crazy, but I was planning on replacing the cam either way. I hope there is some combination of cam, lifters, and springs that would be good for my application. At some point I want to really upgrade the motor, but for this season I just want to freshen it, and make it reliable. Any input is greatly appreciated.

I've got a 502 cam and springs that made 450 HP on a Gen 6 block.. you may need a better exhaust....

A stock rebuild on the bottom end would be fine.

As far as performance gains, couple thoughts. Rebuilding the stock heads, with a good valve job, a little cleanup work on the bowl area, a hyd roller conversion, aftermarket intake and carb, will give a nice increase. Cam choice will be limited with the captains choice for sure though.

However, with the cost of machine work, and depending on how much work you're heads may need, another option is to look into a new set of castings. When you factor in the cost to rebuild the old heads, or sell them as is on ebay or craigslist, and get into a more modern, much better performing head, its sometimes more viable to go with new heads. To get 600+ HP with a decent set of aftermarket heads and cam combo, is realistic. Plus if you're sticking with the stock pistons, you can get aftermarket aluminum heads that not only flow better, but also available with different chamber sizes to raise the compression up, which also helps with power, and when ditching iron for aluminum, you can go a little higher on compression. Plus with good flowing heads, you can stay conservative on the cam duration and overlap, and still make good power.

What year is the engine? Some of the early 502 mag carbs used the bowtie block, which is a pretty nice block to have.

The motor is in a 1991 Fountain Fever. I might just rebuild it totally stock now to save money for better upgrades next year

Does your have the fuel pump mounted to the block? If so you probably have a mark iv bowtie block . Great block to start with on a high performance build.

The fuel pump is mounted to the block in the same location as a automotive application. What have people used as far as rebuild components. Such as bearings, piston rings, oil pump, gaskets, etc?