seafordguy

Spoke to a couple dyno guys and realized I wish I never would have put my blowers back on for my style of boating. So, If I wanted to pull my blowers off (177's) and just go NA could I get by with this cam that I already have in it?

Specs: .235int and 241exh - .646int lift and .629exh

Gen 6 -502's with GM heads, cmi's.

Any thoughts? Not trying to make any power, just want simple and low hassle for a couple years.....

getrdunn

iTrader: (7)

Personally I'd say they look pretty good NA or SC. You'll. Be fine. Assume they're 114 lsa
Either way you'll have good cams. No worries. Use them. You won't be sorry.

Griff

You will probably loose 75-100 hp by removing them and going NA. What is the comp ratio???
You will probably need to drop down in prop pitch as well.

snapmorgan

iTrader: (2)

177's should be simple and hassle free. there will be some expense to buy different intakes and carbs if you ditch them. I would be more worried about compression ratio than I would the camshaft

sutphen 30

what compr ratio do you have?

Crude Intentions

iTrader: (1)

Merc motors were all generallylow compression anyhow. Mostly in the 8.75:1 or so range. I don't think it would be that big of a deal.

Eliminated572

Ya designed to run 87 octane. The "SC" series with blowers were what? 7.5:1? Way low...

seafordguy

Comp Ratio is 9.1.

I don't mind losing the power. My problem is with my constant idling, and delicate way I cruise around I am always running rich. The discussion was that with those small blowers and the heat they make you have to really run rich - Hard to find a balance between leaving enough jet in it to protect it at WOT, but allowing me to cruise around at 3,200 like I do 99% of the time I'm on plane.

Eliminated572

Just some tuning... you already verified power valve size and PVCR size correct? A common mistake made, is that guys have great AFR cruising/idling then worry about lean up top... To correct this issue they enrichen mixture screws (Which has very little affect at WOT or cruise), and they put larger jets in (Which affects everywhere from off plane driving, cruise, and WOT). They overlook to tuning where they specifically need the fuel at WOT (PVCR).

You need to dial in a clean idle with the mixture screws. Then leave them. Then dial in clean cruise with the main jets Verify vacuum so you make sure the power valves are shut... Then leave them. Then dial in PVCR and power valve for WOT. Now if you find it terribly lean at WOT you don't want a crazy amount of PVCR and small main. Reason being is when the power valves open you have a huge change in fueling. But its not uncommon to require high flow power valves to support enlarged pvcr's. Now at the end of the day, you have a clean running boat idle and cruise. Then proper enrichment for WOT..

mike tkach

iTrader: (3)

with the right carb and proper tuning a good air fuel ratio from idle to wot can be had with the blower.