horizontal reeds v/s vertical reeds?

[david martin]

Can someone tell me the differance in power I could get out of a 200 blackmax if I change the motor to a horizontal reed set up.
I have everything to do this project,I just dont know if its worth taking a good running motor apart.This motor is going to go back on my 19ft nordic picklefork.Also it is a carb motor.
Thanks for any info.
David

[dynobo]

What year 200 do you have. I know all the later 200's were hor. reed. Seems like maybe the early ones (late 70's) may have been vert. Anyways to answer the question probably in the 20 hp range.

[david martin]

I honestly do not know what year the powerhead is?I know it is a 200 merc with vertical reeds.How can I tell what year the powerhead is?
thanks
David

[dynobo]

It's hard to tell w/o serial number. Are you sure it's not a 150/175. Seems like my '79 model has hor. reeds also. Ofcourse someone could have swapped it out along the way.

[TD]

I honestly do not know what year the powerhead is?I know it is a 200 merc with vertical reeds.How can I tell what year the powerhead is?
thanks
David

No where close to a 20hp gain with just this change.

[Rusrog]

No where close to a 20hp gain with just this change.

Yes when done right it does give a 20-25 horse power increase. There were 142 175's that were built in the mid 80's. These were essentially a 200 with Verticle reeds and a slightly different carbureator and tuning. Change the front case half on a 142cid chrome bore motor and it will make right at 200 horsepower.

[gotboostedvr6]

Rus your theory is flawed
Merely changing the front half will not supply enough air to produce 20-25 hp at the prop.

david what style heads do you have?

One piece or two?

Also there might be a date stamp on the port side of the block

maybe a serial number on the clamp..

[gotboostedvr6]

also have you ever had the heads off? did it look like the head bolts inserted in to the sleeve?

http://forums.screamandfly.com/forum...4&d=1192071292

[Rusrog]

Rus your theory is flawed
Merely changing the front half will not supply enough air to produce 20-25 hp at the prop.

I bet it's not flawed by much. Either that of Mercury was lying to us about one motor or the other. I don't know what this guy has but Mercury made a 175 with a chrome bore 200 back half and a vert front end. The carbs were different but the actual bore size of the venturi was very close... I don't remember for sure but it was in the neighborhood of .100 difference. Probably some minor tuner difference as well. But Carbs, front case half and possibly a tuner difference was all that were different in the 2 motors. Now if the motor in question early gen v-6(1982 & prior)... Yeah... All bets are off.

And while I have never flowed a vert front end on the flow bench... It's pretty poor. It's like engineers took a strong motor and tried to design a way to kill the power & efficiency. That goes for Mercree & Yamaha both. I would bet that the difference is there to sustain another 20 horsepower.

But that's just my opinion...

Russ

[david martin]

I have never had the heads off.I just got this motor back from my brother and he changed the power head back in july 2006.The heads are a 2 piece head.
Thanks
David

[horn5413]

My 81 200 is vertical reed with a crome bore and no finger ports. I think they changed in 83. I did change to an 89 200 with finger ports and horizontal reeds, and there is a nice difference, but I think the finger ports have alot to do with it also. MIKE>>