Verticle verus Horizontal Throttle Butterflys?

[John (Taylor) Gabrowski]

I just viewed some pictures of a Merc 20H gas Modified with a Quincy pipe that has instead of a Tillotson carb with its verticle butterfly it has a OMC carb with a horizontal throttle butterfly??? Supposedly this works okay?

How would that work without causing some serious air/fuel flow problems? Like starving one side of the crankcase at different points in rpm?

Strange setup for a 20H Mod with normal reedblocks and reeds behind the carb.

One more thing. It uses a single ring piston with rings less than half the cylinder face width of a standard Mercury ring. Are any more of those around these days from some distributor?

Other than looking at it there is no other further information on the motor to find out anything or who built it.

[Bunker Hill]

Wouldn't the feul/air mixture become homogenous through the reed induction process? You mentioned "Strange set up for a 20h with "Normal" reed block, Isn't fuel/air mixture a function of the reed block? When you said "Normal" did you mean normal for a 20h, crank mounted reeds or "Normal" by today's petal standard?

[John (Taylor) Gabrowski]

Your logic is fine by me but as the air/fuel stream increases in speed with the engines rpm would a high/low air-fuel stream separation not occurr? These OMC carbs are meant for OMC engines with radial positioned reed petals systems. The brass reed block 20Hs came with are in this engine with metal reeds.

What has me bugged is that some years ago I put Tillotson HR self pumping floatless snowmobile carbs on their normal way with horizontal butterflys on a Merc 44 Mod and I ran into tunning and sparkplug coloration differences. I turned the carbs on extra adapters to give me verticle butterflys and everything straightened right out and the Merc ran no different as if it had the stock Tillotson KA7A type carbs except these HR carbs seemed more throttle responsive.

I have me a box full of those same OMC carbs and it has me thinking of trying them to see the differences too.