1990s Force 70 and 75

[Frank Acampora]

The Mercury designed Force single carb 70 and 75 had a baffle cast into the manifold, partially blocking the carb AND there was a baffle plate bolted to the front of the carb also blocking part of the inlet.

QUESTION: Since they were at odd angles and aligned with each other, were these baffles meant to restrict airflow through the carb OR were they meant to direct airflow to ensure even air/fuel distribution to all three vertical reed blocks?

Thinking of removing these as an experiment, but don't want to "lunch" an engine in the process. Factory put them there for a reason-----

Any Mercury engineers here on the board?

 

[Goneflyin]

Re: 1990s Force 70 and 75

I'm not a Merc engineer, just a tinkerer but I'd guess it could be there to alter the resonance between intake pulses that may work against each other at certain rpm's. Boat motors seem to have pretty broad powerband and maybe the baffles help at a certain rpm range. If the one plate is removeable try it and see if it makes any difference. The plates may work together and pulling one may affect it. Just a silly guess. My experience is mostly piston port bike engines, years ago I did a little roadracing and collected a bunch of books and sae papers on two strokes and found they're part musical instrument, part engine.

When you mentioned restricting airflow it made me think of a guy I worked with who had a BMW head on the flowbench doing the final tweeks and a #2 phillips(shaft end) fell in the port and airflow went up, the effect was repeatable just looked funny.

Bill