Dave1972

What would anyone recommend doing to replace the cap and rotor on my 502 mag EFI? It's got about 400 hours or so on it and I'm just wanting to do a tuneup. Would you recommend the stock replacement parts? If so, from who? Also going to replace the plug wires just for the "fun" of it while I'm doing it. Do you recommend the Merc wires or aftermarket from Summit? I've seen a few threads about getting the MSD's 3122 (90*boot like stock) as well as the Taylor 135* boot....are both of these sets cut to length? I've never made my own wires...do I need special crimper and/or stripper? The motor is not stock but does utilize the stock ignition....any benefits from using aftermarket wires or should I just go with Merc for simplicity? Perhaps get the HP500EFI wires instead of 502mag??? What is the difference?

Thanks in advance,
Dave

ursus

hp500's are 8mm and blue and about $5 more than stock merc seem to work well for me on 502 mag, but no better than the stock red ones tho there not as purdy IMO

Dennis Moore

I did a magazine article about (and collected) different caps and rotors. The Mercruiser cap and rotor is actually a better quality cap and rotor than the AC Delco. The one I really liked was the tan cap and rotor from Accell. I don't share my opinion on the other parts made by Accell though. Change the plug wires for fun because it won't help performance!

Dennis Moore
FAMILY AND PERFORMANCE BOATING MAGAZINE

454hoho

Dennis I take it you have a neutral position on accell wires and plugs

Tinkerer

With 400 hrs on those wires and you don't suggest replacing them??? Open your engine cover on a humid night with no lights on and watch the light show. The wires are probably shot. If you don't believe me just ohm them out against the new ones. The wires that you are comparing must be close to the same length. WATERFOUL just had to change his because they were bad and he lost speed at the LOTO shoot out. I run the taylor SPIRAL PRO wires and they come in a lot of colors.

Ric232

I think Dennis is saying that there is no benefit to be gained by using anything but stock plug wires. The wires last an awfully long time in a boat because the engine compartments are stay so cool and clean. The cap and rotor, on the other hand, start corroding right away and rob you of WOT rpm.

454hoho

I agree with all these posts, especially tinkerboater since i have seen a light show on a friends boat late at night he developed a slight miss. When the hatch was raised it looked like a mini lighting storm that you fail to see or pickup in day light. Old wires

deboatmon

I cannot imagine running a cap and rotor 400 hrs. I replace mine @ 100 hrs. max. It's so easy and cheap. To me caps and rotors are a no brainer. If you're going 400 hrs on those pieces, you probably aren't much in to doing minor routine maintenance yourself. For me, it's just normal to change @ 100 hrs. There are better caps than the Merc cap too. Much better.

My $.02 worth.

Dave1972

deboatman,
I'm not saying that the cap and rotor and plug wires have not been changed in 400 hours. I am plenty capable and knowledgeable that a cap and rotor won't last that long and give you optimum performance. The motor was just rebuilt and I am wanting to have everything new at the same time. You mentioned that you would suggest other caps/wires....what is your suggestion?

Nobody has offered a part number or specific brands other than the stock merc stuff....anyone??????

454hoho

Dave send a e-mail to D.Moore in ref. to his reply he stated using
accell cap & rotor (good choice) most likely has part number etched in his mind.