Just bought an msd 6 system for my hp500 carb'd. I know the stock merc rev limiter is set for either 5450 or 5350 but I have heard of people bumping it up. Also has anybody messed with tuning the msd with a laptop?

oops, I'm using my dad's laptop and just realized I'm logged in to his account. this is disturbedvelo22

I thought stock 500's had a 5200 redline....

It would depend on if the valve springs were stock hp500 and how many hours on them. If the springs were decent aftermarket with low hours and set up right, 5500rpm would be my number. That engine can make power up close to that level with an upgraded valvetrain. Stock, used springs, 5000rpm would be safe.

i believe the limiter is at 5250. I had a carbed 500HP i took the rev limiter off and would Run 5600rpm's all day long on, the thing was the best motor ive ever owned, bullet proof

I've run mine up to 5600 rpm for 5 years with no issues.

the springs have 50 hours on them and they are springs recommended as stock replacements. I'm pretty sure (at least its what the rpm gauge is reading) the motor is buzzing 5450 with the stock ignition. Did you guys set the distributer up like the stock?

BTW my motors floated the valves with the stock lifters/valve springs at 57-5800. Probably need to stay below that.

Thunderstruck, What props are you running?

So stock replacement valve springs i should be all good at 5600?

Recommended WOT RPM of the 500HP is 4800-5200rpms. The rev limiters are supposed to be at 5350rpm, but vary somewhat and also tachs can be off. If you have TB IV ignition, the rev limiter is a separate part and can't be changed. If its a TB V, then I think you can have the limiter in the ECM changed.