No luck with Boysen reeds!!

[proprider]

Couldn't agree more! They have a great product and have always shared their knowledge and given me awesome service.

Carson's are really good guys to deal with, and build some pretty wicked engines.

[BmJuby]

Good info. Might be the cause of some symptoms in my fresh 20H conversion. Hopefully it's a carb issue....

[Smitty]

Jeff, if we could watch a crankshaft squirm and flex at peak rpm under that strobe light . . . . The old racing mechanic Smokey Yunick had the opportunity to do that kind of thing with automotive V-8 racing engines, and he said the camshaft writhed like a snake on an electric skillet. Old Merc crankshafts are pretty scrawny, and don't have enough good main bearings in the fours and sixes . . . .

[pops67g]

So after listening to all the horrible things that go on inside our motors I still have had zero problems with the dual reed setup. I even was hesitant to put them in and have no reservations about using them again.

[Dave M]

Balance

Was all that squirming with a balanced crank or stock crank ? I would suspect in theory that a balanced crank would not squirm as much as a stock one.

As far as the dual staged reeds, I am not a fan, but as Pops67G points out, some don't have issue with them. Perhaps a combination of things need to be correct before they will work.

[pops67g]

I suspect...

that the main factors involved in reed life are reed stop height and length. I am using unmodified stops in this motor which probably gives more support to the open reeds. If you shorten the stops the reed is just going to flex more. When Boyesen, or whomever, designs a reed all they can do is copy the dimensions of the stock steel reed because nothing else will fit anyway.

[Smitty]

You must not know about old Smokey, Dave, because anything he built would have been balanced.

[bill boyes]

Russ Hill sr put my 55H crank in V blocks with a dial indicator on the ctr main. It was out 008. The crank was Bent .008. Gezz. He put it into a small press and bent it until i heard a pop. Damm it broke I thought. Nope, back in the V blocks and the runout was less than .001. Man that was a good motor after that.

[Guest]

4 cylinder cranks

When building an engine we always check the crank to make sure that it will run true. I believe that the Merc crank is very well supported. First you have large ball bearings at the upper and lower ends of the crank. The early cranks had double row needle bearing at the center which we like best and then the reed blocks also form a bearing surface. That gives you five main bearings on a 4 cylinder. If the crank was walking all over I would assume that the reed blocks would be wallowed out due to this movement. We turn our engine in the mid 8,000 rpm range and have not had an issue in the labyrinth seal area. In most cases you can see the trace of the read block on the crack but it is rare that you will hurt them. We run both the aluminum and bronze units and they appear to perform about the same, although I like the bronze one best.

Alan

[BmJuby]

We've determined that the dual stage reeds are the reason for our lack of power in our 20H conversion. Rebuild will happen over the winter.

[jeff55v]

I have tried the Boyesen two stage reeds in my Tohatsu and noticed no performance difference whatsoever over the factory steel reeds. I didn't mention it previously because comparing the Merc to the Tohatsu is like apples and oranges.
By the way, it takes 30 minutes to change out the reeds in a Tohatsu. And that is if I take my time.