OMC 5.0 Performance

[clarkmcmp]

I have a 1990 Sunbird corsair 205, OMC 5.0 ford with 2bbl carb. I had a 19 pitch prop and am trying a 21 pitch now. At full throttle, my tach say 3000rpm, speed is 42. This is with a full tank of gas and 3.5 on board. I have hit 45 max with a lighter load. I don't think my tach is accurate. Shouldn't I be getting closer to 50 mph? I would guess I am really around 4200 RPM. What is the best money spent to get to 50mph. I am also still using points.

 

[SpinnerBait_Nut]

Re: OMC 5.0 Performance

Boat topics and questions, non repair forum.

 

[QC]

Re: OMC 5.0 Performance

The absolute first thing you need to do is get the tach accurate Can't make any decisions on the prop size without it right. Check the back of the tach, there is usually a switch for 4, 6 or 8 cyl. Start there first, you might get lucky. Also, you can get a cheap Photo Tach or shop tach to confirm. It really is where you must start.

50 MPH is a big barrier. We all want the next one, I am still working on 60 . . . That 205 with a 5.0 is gonna be really tough to get that fast. It's just horsepower required vs. horsepower available. Lets see if we can get you all you have available, but we need the tach first.

 

[MikDee]

Re: OMC 5.0 Performance

Get a new tach, and put a 4bbl carb on that thing, It'll bring you closer to 50.