Merc 420 to 525sc in a Formula 242.
 

I have an 86 242. I have a 420hp Mark IV engine. I just purchased a 525sc blower setup. I am planning on leaving the low hour short block as is. I am having the heads looked over and inconel exhaust valves installed. There is just a few grey areas.

Does anyone know if the DUI distributor will clear a 177 blower?

I suspect my motor has stock 454 mag oil system. Combo oil and PS cooler with the oil filter on the exhaust. I have a new 10778 Melling oil pump going in. I would like to either get a stock HP500 oil system or a nice aftermarket setup. Any thoughts on the required oil system for my HP level?

I have also heard of swapping to a 134561 cam versus the 132561 I have now. i am not really looking to spend the extra to go roller right now. Any flat cams with good results?

Thanks in advance.

Here are some pics of the current setup and the blower/carb/arrestor setup I bought.

http://i880.photobucket.com/albums/a...65182309_o.jpg
http://i880.photobucket.com/albums/a...82904155_o.jpg
http://i880.photobucket.com/albums/a...79347345_n.jpg

A little off topic but your engine compartment was my inspiration to clean mine up. I'll post pics when done.
Where did you locate your bilge blower hoses? Good luck on your project boat looks great.

They are now by the trim pump. They were not in for the pic.

I don't think the HEI style distributor will clear, but it might.

I would run the 134561 camshaft, 236/246 114LSA .553/571 , and prop it for around 5300-5400rpm.

That combo, will put you in the 575hp/600ft lb range. Wayne272 did the exact same setup to his 454 mags in his 31 Bullet, and dyno'd them. If you plan on running a water thermostat, you're oil cooler may not be sufficient. If you do not plan on running water thermostats, it might be ok. If you are not going to run a water thermostat, I highly recomend an oil thermostat.

Watch your ignition curve, and your jetting. Once that is dialed in, you should have a very reliable combo. I would run a AR134 plug, 5673-8 NGK, or MR41T delco.

So basically the thermostat slows down the water flow to the engine, therefore the water going through the oil cooler is also slower, allowing less heat to be removed from the oil. If I go to a crossover setup, more water will pass through the cooler, allowing cooler oil, but i would then need an oil thermostat to bring the oil up to temp? Am I understanding this right?

Yes and no. Main thing people forget, is an engines water temperature, has a direct relationship to the oil temperature. Some vehicles, dont have external oil coolers, the oil temp is maintained from the temperature of the engine. So, the colder water temp engine, will also serve as an oil cooler so to speak. Having a water stat that warms the engine to 150 degrees, also helps warm the oil, and vice versa.

The best advice i have, would be to invest in an oil thermostat, replace the stock merc crappy lines, and replace with good flowing an fittings, and a good sized oil cooler. I would do that, before replacing the oil pumps. The stock pump is fine for what youre doing imo. Mercs fittings were restrictive . You want that oil to flow quickly to the cooler, filter, and back to the engine in an efficient manner. I would do -10AN oil lines, with full flow ends. The stock HP500 style thermostatic filter head mount works great as well.

I get what you are saying. Engines remove heat by both coolant and oil. So if I run cooler water temp, the parts will run cooler, then there will be less heat for the oil system to remove. I am currently running a 160 stat. The boat consistently runs 155*.

It would seem to me that a cooler block would also aid in preventing detonation with 8.75 compression and boost.

The oil lines coming off the block are very large, like garden hose size. The ones to the filter would be the ones that look small, along with the fittings at the filter. I already have the new pump. It seems many people like the 10778 pump. I would feel better using it.

I had a trouble free summer (48hours) last year. I really just want this thing to be turn key all summer.

Its mainly some of the inverted flare fittings merc used that are restrictive.

Sounds like a fun upgrade. I think youll like the way it runs

Joe, do you think my risers are long enough for that bigger cam? I was also just looking at CPs website. They have a 120* thermostat. Would that be cool enough?

Ive seen that cam work for 700 hours in 454/370s with stock center rise iron manifolds, with no reversion, that were rebuilt by competition marine center many years ago.