Author Topic: What Size Venturi for Merco 61 (Read 742 times)

Brian Thwaites · « **on:** June 18, 2008, 01:40:38 PM »

My Merco 61 has Venturi size of .260" I think it is too small will not get much above 8800 RPM 13 x 6 prop
think it needs more ummph suggestion on correct size would be much appreciated. Its a new engine with about an hours running in

Bill Hummel · « **Reply #1 on:** June 18, 2008, 02:34:12 PM »

Brian, depending on which version of the Merco, we've seen venturis of .285 up to .305 generally. You might not get much more that 8800 rpm's; the Merco likes that neighborhood. Also, until more time is on the engine, try a 12/5 or 12/6 prop, and at least 50/50 fuel. Nice engines for stunt, old-fashioned "luggers".

Dave Adamisin · « **Reply #2 on:** June 18, 2008, 03:00:36 PM »

Quote from: Brian Thwaites on June 18, 2008, 01:40:38 PM

My Merco 61 has Venturi size of .260" I think it is too small will not get much above 8800 RPM 13 x 6 prop
think it needs more ummph suggestion on correct size would be much appreciated. Its a new engine with about an hours running in

Hi Brian. What Bill said. Also the needle body dia has an impact on this question. The stock Merco (memory kicking in) was I think ~0.155" dia which makes the .260 pretty small. I would start with opening it to .281 and then as high as .304. Probably need muffler pressure for .304. If it's the smaller .135 body .281 is a target for the high end.

Brian Thwaites · « **Reply #3 on:** June 18, 2008, 08:25:04 PM »

thanks guys will measure needle valve and work up from there

Author Topic: What Size Venturi for Merco 61 (Read 742 times)

Brian Thwaites

What Size Venturi for Merco 61

Bill Hummel

Re: What Size Venturi for Merco 61

Dave Adamisin

Re: What Size Venturi for Merco 61

Brian Thwaites

Re: What Size Venturi for Merco 61