I have a 96 27 foot powerquest that had a 502 MPI in it. One of the heads rotted out and I got water in the cylinder so I am rebuilding and going with a simple carb set up. It is a roller cam motor that is bored 30 over running CMI e-top headers with a ZZ502-502 cam. Any recommendations on a distributor. I wanted to stay away from the MSD, I was thinking DUIs sounded like a good deal, do I need any kind of a shift interrupter? Do I need to run a melonized gear or composite for that forged camshaft? I am going with the 800 CFM holly carburetor in a dual plane intake how big of an electric fuel pump should I be running and what size lines? I am also looking to buy a wire harness ,my alternator is on the lower forward right side of the engine. The new cast-iron heads I am buying are a direct replacement for the originals but are said to flow a little bit better and give me a bout 20 more horsepower. Any sound advice is greatly appreciated.

What heads you buying

throw the other original head away. don't sell it. it is about to rot out too. spent just as much time full of salt water as the other one. take a close look at the water passages in the block. it is getting thin all over. you need to flush the tampa bay salt out religiously when boat comes out or gets docked.

3/8 stsinless tube or braided lines. 80-100gph pump, fuel pressure regulator at 8lbs. Use ignition protected marine rated electronics. There is a Lot of good stuff out there. I'm other ppl here will have some good suggestions.

You should have a Bravo drive so no shift interrupter is needed

You can use the DUI distributor.
you could also use the Merc distributor with a Daytona sensors ignition box for more tuning parameters.
you will need a melonized gear for the GM cam.

From the GM ZZ 502 install manual,

"Distributor Gear


[img]file:///page2image16072[/img]
A melonized distributor gear must be used in these 502/502 engine assemblies. The deluxe 502/502 engine assembly comes with a melonized distributor gear. For the base 502/502 engine assembly you must install an HEI distributor, part number 93440806, with melonized gear or install a melonized gear on your distributor. Use part number 10456413 gear for 31/64” diameter distributor shafts or use part number 10493532 gear for 27/64” diameter distributor shafts. "


Jeff

Have you run that cam yet? I think it has a lot of overlap. What exhaust? Might be worth finding a 525EFI takeout or cloning it. I don't think that 110lsa is going to be a good deal.

I like the DUI stuff, no problems. You can run the 889275T pump. Can find them for $100.

If you haven't bought the cam yet, I would go with a Crane 168741 or 525EFI cam over the ZZ502 cam.

I am throwing away both of the old original heads. The new heads are a direct replacement for the o88 original heads they are cast in New Zealand and have extra thickness around the water jackets they come with inconel exhaust valves and a swirl polish on the backside of the valves most of the builders here highly recommend them for the rebuilds because of their durability and good performance they are for marine use. I have run that ZZ502 cam for about a year since the last time it was rebuilt and I had no problems with water in the oil or reversion problems as long as I keep my idol above 850 I think I should be OK and before I shut down I always bump the throttle a little bit there is also another distributor out there that I see a lot I think it's a Pertronics. the trigger style is a hall affect what is the difference between that and a magnetic pick up that the DUY has? Also the guy putting my heads together has been informed that I'm using that ZZ502 cam so if I were to purchase another camp he would have to change the valve springs or something to match the camp it's just a little bit too late so I'm going to go with the 502 I think it'll be OK. Glad I don't need to shift interrupter I have read some posts and people were complaining when they install the new distributor that they got no tax signal do I need a special distributor that has a wire probably gray coming out to run my distributor I could ask that question when I call and purchase one from either summit her performance distributors also one other question I had where would be a good place to buy a new wire harness does anybody have one used and like I said the set up is with my alternator on the lower right-hand side of the engine. thanks again everybody.

Griff have you run one of those in a low compression 502?

168761 might fair a little better. Either way break out the $$$$$ for some long travel lifters!!

Jeff